Texas Instruments | LMR33620-Q1 3.8-V to 36-V, 2-A Synchronous step-down voltage converter (Rev. B) | Datasheet | Texas Instruments LMR33620-Q1 3.8-V to 36-V, 2-A Synchronous step-down voltage converter (Rev. B) Datasheet

Texas Instruments LMR33620-Q1 3.8-V to 36-V, 2-A Synchronous step-down voltage converter (Rev. B) Datasheet
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LMR33620-Q1
SNVSB27B – JUNE 2018 – REVISED MARCH 2019
LMR33620-Q1 3.8-V to 36-V, 2-A Synchronous step-down voltage converter
1 Features
3 Description
•
The LMR33620-Q1 automotive-qualified regulator is
an easy-to-use, synchronous, step-down DC/DC
converter that delivers best-in-class efficiency for
rugged applications.The LMR33620-Q1 drives up to
2 A of load current from an input of up to 36 V. The
LMR33620-Q1 provides high light load efficiency and
output accuracy in a very small solution size.
Features such as a power-good flag and precision
enable provide both flexible and easy-to-use solutions
for a wide range of applications. The LMR33620-Q1
automatically folds back frequency at light load to
improve efficiency. Integration eliminates most
external components and provides a pinout designed
for simple PCB layout. Protection features include
thermal shutdown, input undervoltage lockout, cycleby-cycle current limit, and hiccup short-circuit
protection. The LMR33620-Q1 is available in a 12-pin
3 mm × 2 mm VQFN package with wettable flanks.
1
•
•
•
•
AEC-Q100 qualified for automotive applications:
– Device temperature grade 1: –40°C to +125°C,
TA
Configured for rugged automotive applications
– Input voltage range: 3.8 V to 36 V
– Output voltage range: 1 V to 24 V
– Output current: 2 A
– 75-mΩ/50-mΩ RDS-ON power MOSFETs
– Peak-current-mode control
– Short minimum on-time of 68 ns
– Frequency: 400 kHz, 1.4 MHz, 2.1 MHz
– Low EMI and low switching noise
– Integrated compensation network
High-efficiency solution
– Peak efficiency > 95%
– Low shutdown quiescent current of 5 µA
– Low operating quiescent current of 25 µA
Flexible system interface
– Power-good flag and precision enable
Create a custom design using the LMR33620-Q1
with the WEBENCH® Power Designer
Device Information(1)
PART NUMBER
LMR33620-Q1
BODY SIZE (NOM)
3.00 mm × 2.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
space
space
2 Applications
space
•
•
space
Infotainment and cluster
Telematics control unit
PACKAGE
VQFN (12)
space
space
Simplified Schematic
Minimum Component Example
BOOT
VIN
VIN
CIN
CBOOT
EN
SW
L1
COUT
PGND
VCC
VOUT
PG
RFBT
CVCC
FB
AGND
RFBB
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
LMR33620-Q1
SNVSB27B – JUNE 2018 – REVISED MARCH 2019
www.ti.com
Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Device Comparison Table.....................................
Pin Configuration and Functions .........................
Specifications.........................................................
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
8
1
1
1
2
3
4
5
Absolute Maximum Ratings ...................................... 5
ESD Ratings.............................................................. 5
Recommended Operating Conditions ...................... 5
Thermal Information .................................................. 6
Electrical Characteristics........................................... 6
Timing Characteristics............................................... 8
System Characteristics ............................................. 9
Typical Characteristics ............................................ 10
Detailed Description ............................................ 11
8.1 Overview ................................................................. 11
8.2 Functional Block Diagram ....................................... 11
8.3 Feature Description................................................. 12
8.4 Device Functional Modes........................................ 16
9
Application and Implementation ........................ 19
9.1 Application Information............................................ 19
9.2 Typical Application .................................................. 19
9.3 Do's and Don'ts ....................................................... 32
10 Power Supply Recommendations ..................... 33
11 Layout................................................................... 34
11.1 Layout Guidelines ................................................. 34
11.2 Layout Example .................................................... 36
12 Device and Documentation Support ................. 37
12.1
12.2
12.3
12.4
12.5
12.6
12.7
Device Support ....................................................
Documentation Support ........................................
Receiving Notification of Documentation Updates
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
37
37
37
37
38
38
38
13 Mechanical, Packaging, and Orderable
Information ........................................................... 38
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision A (November 2018) to Revision B
Page
•
Changed block diagram to fix drawing error......................................................................................................................... 11
•
Added EMI data and filter schematic. .................................................................................................................................. 27
Changes from Original (June 2018) to Revision A
•
2
Page
First release of production-data data sheet ........................................................................................................................... 1
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5 Device Comparison Table
DEVICE OPTION
PACKAGE
LMR33620AQRNX
LMR33620BQRNX
RNX (12-pin VQFN)
3 × 2 × 0.85 mm
LMR33620CQRNX
FREQUENCY
RATED CURRENT
400 kHz
2A
1400 kHz
2A
OUTPUT VOLTAGE
Adjustable
2100 kHz
2A
LMR33620CQ5RNX
RNX (12-pin VQFN)
3 × 2 × 0.85 mm
2100 kHz
2A
5-V fixed
LMR33620CQ3RNX
RNX (12-pin VQFN)
3 × 2 × 0.85 mm
2100 kHz
2A
3.3-V fixed
LMR33620AQ5RNX
RNX (12-pin VQFN)
3 × 2 × 0.85 mm
400 kHz
2A
5-V fixed
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6 Pin Configuration and Functions
RNX Package
12-Pin VQFN
Top View
SW
12
11 PGND
PGND 1
VIN
2
10 VIN
NC
3
9 EN
BOOT
4
8 PG
5
VCC
6
7
AGND
FB
Pin Functions
PIN
TYPE
DESCRIPTION
NO.
NAME
1, 11
PGND
G
Power ground terminal. Connect to system ground and AGND. Connect to bypass capacitor with short wide
traces.
2, 10
VIN
P
Input supply to regulator. Connect a high-quality bypass capacitor(s) directly to this pin and PGND.
3
NC
—
On the VQFN package, connect the SW pin to NC on the PCB. This simplifies the connection from the CBOOT
capacitor to the SW pin. This pin has no internal connection to the regulator.
4
BOOT
P
Boot-strap supply voltage for internal high-side driver. Connect a high-quality 100-nF capacitor from this pin to
the SW pin. On the VQFN package connect the SW pin to NC on the PCB. This simplifies the connection from
the CBOOT capacitor to the SW pin.
5
VCC
P
Internal 5-V LDO output. Used as supply to internal control circuits. Do not connect to external loads. Can be
used as logic supply for power-good flag. Connect a high quality 1-µF capacitor from this pin to GND.
6
AGND
G
Analog ground for regulator and system. Ground reference for internal references and logic. All electrical
parameters are measured with respect to this pin. Connect to system ground on PCB.
7
FB
A
Feedback input to regulator. Connect to tap point of feedback voltage divider. DO NOT FLOAT. DO NOT
GROUND. With the fixed output voltage version, connect this input directly to VOUT near the output capacitor.
8
PG
A
Open drain power-good flag output. Connect to suitable voltage supply through a current limiting resistor. High
= power OK, low = power bad. Flag pulls low when EN = Low. Can be left open when not used.
9
EN
A
Enable input to regulator. High = ON, low = OFF. Can be connected directly to VIN; DO NOT FLOAT.
12
SW
P
Regulator switch node. Connect to power inductor. On the VQFN package the SW pin must be connected to
NC on the PCB. This simplifies the connection from the CBOOT capacitor to the SW pin.
A = Analog, P = Power, G = Ground
4
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7 Specifications
7.1 Absolute Maximum Ratings
Over the recommended operating junction temperature range (1)
MIN
MAX
VIN to PGND
PARAMETER
–0.3
38
EN to AGND (2)
–0.3
VIN + 0.3
FB to AGND
–0.3
5.5
0
22
PG to AGND (2)
Voltages
AGND to PGND
–0.3
0.3
SW to PGND
–0.3
VIN + 0.3
SW to PGND less than 100-ns transients
–3.5
38
BOOT to SW
–0.3
5.5
UNIT
V
V
VCC to AGND (3)
–0.3
5.5
TJ
Junction temperature (4)
–40
150
°C
Tstg
Storage temperature
–55
150
°C
(1)
(2)
(3)
(4)
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
The voltage on this pin must not exceed the voltage on the VIN pin by more than 0.3 V
Under some operating conditions the VCC LDO voltage may increase beyond 5.5V.
Operating at junction temperatures greater than 125°C, although possible, degrades the lifetime of the device.
7.2 ESD Ratings
VALUE
V(ESD)
(1)
Electrostatic discharge
Human-body model (HBM), per AEC Q100-002
HBM ESD Classification Level 2
UNIT
(1)
±2500
V
Charged-device model (CDM), per AEC Q100-011
CDM ESD Classification Level C5
±750
AEC Q100-002 indicates that HBM stressing shall be in accordance with ANSI/ESDA/JEDEC JS-001 specification.
7.3 Recommended Operating Conditions
Over the recommended operating temperature range of –40 °C to 125 °C (unless otherwise noted)
VIN to PGND
Input voltage
EN
PG
(2)
(2)
(1)
MIN
MAX
3.8
36
0
VIN
0
18
UNIT
V
Adjustable output voltage
VOUT (3)
1
24
V
Output current
IOUT
0
2
A
(1)
(2)
(3)
Recommended operating conditions indicate conditions for which the device is intended to be functional, but do not ensure specific
performance limits. For ensured specifications, see Electrical Characteristics.
The voltage on this pin must not exceed the voltage on the VIN pin by more than 0.3 V.
The maximum output voltage can be extended to 95% of VIN; contact TI for details. Under no conditions should the output voltage be
allowed to fall below zero volts.
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7.4 Thermal Information
The value of RθJA given in this table is only valid for comparison with other packages and can not be used for design
purposes. These values were calculated in accordance with JESD 51-7, and simulated on a 4-layer JEDEC board. They do
not represent the performance obtained in an actual application. For design information see Maximum Ambient Temperature
section.
LMR336x0
THERMAL METRIC (1) (2)
RNX (VQFN)
UNIT
12 PINS
RθJA
Junction-to-ambient thermal resistance
72.5 (2)
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
35.9
°C/W
RθJB
Junction-to-board thermal resistance
23.3
°C/W
ψJT
Junction-to-top characterization parameter
0.8
°C/W
ψJB
Junction-to-board characterization parameter
23.5
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
N/A
°C/W
(1)
(2)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
The value of RθJA given in this table is only valid for comparison with other packages and can not be used for design purposes. These
values were calculated in accordance with JESD 51-7, and simulated on a 4-layer JEDEC board. They do not represent the
performance obtained in an actual application. For design information see Maximum Ambient Temperature section.
7.5 Electrical Characteristics
Limits apply over the operating junction temperature (TJ) range of –40°C to +125°C, unless otherwise stated. Minimum and
maximum limits are specified through test, design or statistical correlation. Typical values represent the most likely parametric
norm at TJ = 25°C, and are provided for reference purposes only. Unless otherwise stated, the following conditions apply: VIN
= 12 V, VEN = 4 V.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
SUPPLY VOLTAGE
VIN
Minimum operating input
voltage
IQ
Non-switching input current;
measured at VIN pin (1)
VFB = 1.2 V
ISD
Shutdown quiescent current;
measured at VIN pin
EN = 0
VEN-VCC-H
EN input level required to turn
on internal LDO
Rising threshold
VEN-VCC-L
EN input level required to turn
off internal LDO
Falling threshold
0.3
VEN-H
EN input level required to
start switching
Rising threshold
1.2
VEN-HYS
Hysteresis below VEN-H
Hysteresis below VEN-H; falling
100
mV
ILKG-EN
Enable input leakage current
VEN = 3.3 V
0.2
nA
3.8
V
24
34
µA
5
10
µA
1
V
ENABLE
V
1.231
1.26
V
INTERNAL SUPPLIES
VCC
Internal LDO output voltage
appearing at the VCC pin
VBOOT-UVLO
Bootstrap voltage
undervoltage lock-out
threshold (2)
6 V ≤ VIN ≤ 36 V
4.75
5
5.25
2.2
V
V
VOLTAGE REFERENCE (FB PIN)
VFB
Feedback voltage; ADJ option
VFB
Feedback voltage; 3.3-V fixed
option
VFB
IFB
(1)
(2)
6
0.985
1
1.015
V
3.3 V fixed output voltage option
3.26
3.3
3.36
V
Feedback voltage; 5-V fixed
option
5 V fixed output voltage option
4.95
5
5.095
V
Current into FB pin; ADJ
option
FB = 1 V
0.2
50
nA
This is the current used by the device open loop. It does not represent the total input current of the system when in regulation.
When the voltage across the CBOOT capacitor falls below this voltage, the low side MOSFET is turned on to recharge CBOOT.
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Electrical Characteristics (continued)
Limits apply over the operating junction temperature (TJ) range of –40°C to +125°C, unless otherwise stated. Minimum and
maximum limits are specified through test, design or statistical correlation. Typical values represent the most likely parametric
norm at TJ = 25°C, and are provided for reference purposes only. Unless otherwise stated, the following conditions apply: VIN
= 12 V, VEN = 4 V.
PARAMETER
TYP
MAX
3.3 V fixed output voltage option, FB = 3.3 V
1.6
2
µA
Current into FB pin; 5-V fixed
option
5 V fixed output voltage option, FB = 5 V
2.9
3.5
µA
ISC
High-side current limit
LMR33620
2.9
3.5
4
A
ILIMIT
Low-side current limit
LMR33620
1.95
2.45
2.9
A
IPEAK-MIN
Minimum peak inductor
current
LMR33620
IZC
Zero current detector
threshold
IFB
Current into FB pin; 3.3-V
fixed option
IFB
TEST CONDITIONS
MIN
UNIT
CURRENT LIMITS (3)
0.54
A
-0.106
A
SOFT START
tSS
Internal soft-start time
2.9
4
6
ms
POWER GOOD (PG PIN)
VPG-HIGH-UP
Power-good upper threshold rising
% of FB voltage
105%
107%
110%
VPG-HIGH-DN
Power-good upper threshold falling
% of FB voltage
103%
105%
108%
VPG-LOW-UP
Power-good lower threshold rising
% of FB voltage
92%
94%
97%
VPG-LOW-DN
Power-good lower threshold falling
% of FB voltage
90%
92%
95%
VPG-HIGH-UP (fixed
output option)
Power-good upper threshold rising Fixed output voltage
option
% of FB voltage
104%
106%
110%
VPG-HIGH-DN (fixed
output option)
Power-good upper threshold falling Fixed output voltage
option
% of FB voltage
102%
104%
108%
VPG-LOW-UP (fixed
output option)
Power-good lower threshold rising Fixed output voltage
option
% of FB voltage
91%
93%
97%
VPG-LOW-DN (fixed
output option)
Power-good lower threshold falling Fixed output voltage
option
% of FB voltage
89%
91%
95%
tPG
Power-good glitch filter
delay (4)
RPG
Power-good flag RDSON
VIN-PG
Minimum input voltage for
proper PG function
50-µA, EN = 0 V
VPG
PG logic low output
50-µA, EN = 0 V, VIN = 2V
ƒSW
Switching frequency
"A" Version
340
400
460
kHz
ƒSW
Switching frequency
"B" Version
1.2
1.4
1.6
MHz
ƒSW
Switching frequency
"C" Version, RNX package
1.8
2.1
2.3
MHz
60
170
VIN = 12 V, VEN = 4 V
76
150
VEN = 0 V
35
60
µs
Ω
2
V
0.2
V
OSCILLATOR
(3)
(4)
The current limit values in this table are tested, open loop, in production. They may differ from those found in a closed loop application.
See Power-Good Flag Output for details.
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Electrical Characteristics (continued)
Limits apply over the operating junction temperature (TJ) range of –40°C to +125°C, unless otherwise stated. Minimum and
maximum limits are specified through test, design or statistical correlation. Typical values represent the most likely parametric
norm at TJ = 25°C, and are provided for reference purposes only. Unless otherwise stated, the following conditions apply: VIN
= 12 V, VEN = 4 V.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
MOSFETS
RDS-ON-HS
High-side MOSFET ONresistance
RNX package
75
145
mΩ
RDS-ON-LS
Low-side MOSFET ONresistance
RNX package
50
95
mΩ
7.6 Timing Characteristics
Limits apply over the operating junction temperature (TJ) range of –40°C to +125°C, unless otherwise stated. Minimum and
maximum limits are specified through test, design or statistical correlation. Typical values represent the most likely parametric
norm at TJ = 25°C, and are provided for reference purposes only. Unless otherwise stated, the following conditions apply: VIN
= 12 V, VEN = 4 V.
NOM
MAX
tON-MIN
Minimum switch on-time
RNX package
MIN
68
80
tOFF-MIN
Minimum switch off-time
RNX package
52
70
ns
tON-MAX
Maximum switch on-time
7
9
µs
8
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UNIT
ns
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7.7 System Characteristics
The following specifications apply to a typical applications circuit, with nominal component values. Specifications in the typical
(TYP) column apply to TJ = 25°C only. Specifications in the minimum (MIN) and maximum (MAX) columns apply to the case
of typical components over the temperature range of TJ = –40°C to 125°C. These specifications are not ensured by
production testing.
PARAMETER
VIN
Operating input voltage range
Output voltage regulation for VOUT = 5
V (1)
VOUT
Output voltage regulation for VOUT = 3.3
V (1)
TEST CONDITIONS
VOUT = 3.3 V, IOUT= 0 A
MIN
TYP
MAX
3.8
36
VOUT = 5 V, VIN = 7 V to 36 V, IOUT = 0 A to
max. load
–1.5%
2.5%
VOUT = 5 V, VIN = 7 V to 36 V, IOUT = 1 A to
max. load
–1.5%
1.5%
VOUT = 3.3 V, VIN = 3.8 V to 36 V, IOUT = 0 A
to max. load
–1.5%
2.5%
VOUT = 3.3 V, VIN = 3.8 V to 36 V, IOUT = 1 A to
max. load
–1.5%
1.5%
UNIT
V
ISUPPLY
Input supply current when in regulation
VIN = 12 V, VOUT = 3.3 V, IOUT = 0 A,
RFBT = 1 MΩ
VDROP
Dropout voltage; (VIN – VOUT)
DMAX
Maximum switch duty cycle (2)
VHC
FB pin voltage required to trip short-circuit
hiccup mode
0.4
V
tHC
Time between current-limit hiccup burst
94
ms
tD
Switch voltage dead time
TSD
(1)
(2)
Thermal shutdown temperature
25
µA
VOUT = 5 V, IOUT = 1A
Dropout at –1% of regulation,
ƒSW = 140 kHz
150
mV
VIN = VOUT = 12 V, IOUT = 1 A
98%
2
ns
Shutdown temperature
165
°C
Recovery temperature
148
°C
Deviation is with respect to VIN =12 V, IOUT = 1 A.
In dropout the switching frequency drops to increase the effective duty cycle. The lowest frequency is clamped at approximately: ƒMIN =
1 / (tON-MAX + tOFF-MIN). DMAX = tON-MAX /(tON-MAX + tOFF-MIN).
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7.8 Typical Characteristics
Unless otherwise specified the following conditions apply: TA = 25°C and VIN = 12 V
36
12
11
10
Shutdown Current (µA)
Quiescent Current (µA)
34
32
30
28
26
-40C
24
25C
22
5
10
15
20
25
30
35
Input Voltage (V)
8
7
6
5
4
3
-40C
2
25C
1
125C
20
0
9
125C
0
0
40
5
20
25
30
35
40
Input Voltage (V)
C003
EN = 0 V
Figure 1. Non-Switching Input Supply Current
Figure 2. Shutdown Supply Current
600
1.35
590
1.30
EN Threshold Voltage (V)
580
Output Current (mA)
15
C005
VFB = 1.2 V
570
560
550
540
530
-40C
520
25C
510
500
0
10
1.25
1.20
1.15
1.10
UP
1.05
125C
DN
1.00
5
10
15
20
25
30
35
Input Voltage (V)
VOUT = 0 V
40
±40
±20
0
ƒS = 400 kHz
20
40
60
80
100
120
140
Temperature (C)
C007
C006
See Figure 52
Figure 3. Short-Circuit Output Current
Figure 4. Precision Enable Thresholds
DN
Peak Inductor Current (mA)
OUTPUT VOLTAGE (0.8V/Div)
700
UP
650
600
550
500
-40C
450
125C
400
0
0
INPUT VOLTAGE (1V/Div)
5
10
15
20
25
Input Voltage (V)
IOUT = 1 mA
See Figure 52
IOUT = 0 A
ƒSW = 400 kHz
Figure 5. UVLO Thresholds
10
25C
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VOUT = 5 V
30
35
40
C008
See Figure 52
Figure 6. IPEAK-MIN
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8 Detailed Description
8.1 Overview
The LMR33620-Q1 is a synchronous peak-current-mode buck regulator designed for a wide variety of
automotive applications. Advanced high speed circuitry allows the device to regulate from an input voltage of 20
V, while providing an output voltage of 3.3 V at a switching frequency of 2.1 MHz. The innovative architecture
allows the device to regulate a 3.3 V output from an input of only 3.8 V. The regulator automatically switches
modes between PFM and PWM depending on load. At heavy load, the device operates in PWM at a constant
switching frequency. At light loads the mode changes to PFM, with diode emulation allowing DCM. This reduces
the input supply current and keeps efficiency high. The device features internal loop compensation which
reduces design time and requires fewer external components than externally compensated regulators.
The LMR33620-Q1 is available in an ultra-miniature VQFN package with wettable flanks. This package features
extremely small parasitic inductance and resistance, enabling very high efficiency while minimizing switch node
ringing and dramatically reducing EMI. The VIN/PGND pin layout is symmetrical on either side of the VQFN
package. This allows the input current magnetic fields to partially cancel, resulting in reduce EMI generation.
8.2 Functional Block Diagram
VIN
VCC
INT. REG.
BIAS
OSCILLATOR
EN
ENABLE
LOGIC
BOOT
HS CURRENT
SENSE
1.0V
Reference
PWM
COMP.
ERROR
AMPLIFIER
FB
+
-
+
-
PG
CONTROL
LOGIC
PFM MODE
CONTROL
SW
DRIVER
LS CURRENT
SENSE
POWER GOOD
CONTROL
AGND
PGND
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8.3 Feature Description
8.3.1 Power-Good Flag Output
The power-good flag function (PG output pin) of the LMR33620-Q1 can be used to reset a system
microprocessor whenever the output voltage is out of regulation. This open-drain output goes low under fault
conditions, such as current limit and thermal shutdown, as well as during normal start-up. A glitch filter prevents
false flag operation for short excursions of the output voltage, such as during line and load transients. The timing
parameters of the glitch filter are found in the Electrical Characteristics table. Output voltage excursions lasting
less than tPG do not trip the power-good flag. Power-good operation can best be understood by reference to
Figure 7 and Figure 8. Note that during initial power-up a delay of about 4 ms (typical) is inserted from the time
that EN is asserted to the time that the power-good flag goes high. This delay only occurs during start-up and is
not encountered during normal operation of the power-good function.
The power-good output consists of an open drain NMOS; requiring an external pull up resistor to a suitable logic
supply. It can also be pulled up to either VCC or VOUT, through a 100-kΩ resistor, as desired. If this function is
not needed, the PG pin should be left floating. When EN is pulled low, the flag output is also forced low. With EN
low, power good remains valid as long as the input voltage is ≥ 2 V (typical). Limit the current into the powergood flag pin to less than 5 mA D.C. The maximum current is internally limited to about 35 mA when the device
is enabled and, about 65 mA when the device is disabled. The internal current limit protects the device from any
transient currents that may occur when discharging a filter capacitor connected to this output.
VOUT
VPG-HIGH_UP (107%)
VPG-HIGH-DN (105%)
VPG-LOW-UP (95%)
VPG-LOW-DN (93%)
PG
High = Power Good
Low = Fault
Figure 7. Static Power-Good Operation
12
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Feature Description (continued)
Glitches do not cause false operation nor reset timer
VOUT
VPG-LOW-UP (95%)
VPG-LOW-DN (93%)
< tPG
PG
tPG
tPG
tPG
Figure 8. Power-Good-Timing Behavior
8.3.2 Enable and Start-up
Start-up and shutdown are controlled by the EN input. This input features precision thresholds, allowing the use
of an external voltage divider to provide an adjustable input UVLO (see the External UVLO section). Applying a
voltage of ≥ VEN-VCC_H causes the device to enter standby mode, powering the internal VCC, but not producing
an output voltage. Increasing the EN voltage to VEN-H fully enables the device, allowing it to enter start-up mode
and beginning the soft-start period. When the EN input is brought below VEN-H by VEN-HYS, the regulator stops
running and enters standby mode. Further decrease in the EN voltage to below VEN-VCC-L completely shuts down
the device. This behavior is shown in Figure 9. The EN input may be connected directly to VIN if this feature is
not needed. This input must not be allowed to float. The values for the various EN thresholds can be found in the
Electrical Characteristics table.
The LMR33620-Q1 utilizes a reference-based soft start that prevents output voltage overshoots and large inrush
currents as the regulator is starting up. A typical start-up waveform is shown in Figure 10, indicating typical
timings. The rise time of the output voltage is about 4 ms (see Electrical Characteristics).
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Feature Description (continued)
EN
VEN-H
VEN-H ± VEN-HYS
VEN-VCC-H
VEN-VCC-L
VCC
5V
0
VOUT
VOUT
0
Figure 9. Precision Enable Behavior
14
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Feature Description (continued)
EN, 4V/Div
VOUT, 2V/Div
PG, 5V/Div
Inductor Current, 2A/Div
2ms/Div
Figure 10. Typical Start-up Behavior
VIN = 12 V, VOUT = 5 V, IOUT = 2 A
8.3.3 Current Limit and Short Circuit
The LMR33620-Q1 incorporates both peak and valley inductor current limit to provide protection to the device
from overloads and short circuits and limit the maximum output current. Valley current limit prevents inductor
current runaway during short circuits on the output, while both peak and valley limits work together to limit the
maximum output current of the converter. Cycle-by-cycle current limit is used for overloads, while hiccup mode is
used for sustained short circuits. Finally, a zero current detector is used on the low-side power MOSFET to
implement DEM at light loads (see Glossary). The typical value of this current limit is found under IZC in the
Electrical Characteristics.
When the device is overloaded, the valley of the inductor current may not reach below ILIMIT, (see Electrical
Characteristics table) before the next clock cycle. When this occurs the valley current limit control skips that
cycle, causing the switching frequency to drop. Further overload causes the switching frequency to continue to
drop, and the inductor ripple current to increase. When the peak of the inductor current reaches the high-side
current limit, ISC, (see Electrical Characteristics table) the switch duty cycle will be reduced and the output
voltage will fall out of regulation. This represents the maximum output current from the converter and is given
approximately by Equation 1.
I
I
IOUT max LIMIT SC
(1)
2
If, during current limit, the voltage on the FB input falls below about 0.4 V, due to a short circuit, the device enters
into hiccup mode. In this mode the device stops switching for tHC (see System Characteristics), or about 94 ms
and then goes through a normal re-start with soft start. If the short-circuit condition remains, the device runs in
current limit for about 20 ms (typical) and then shuts down again. This cycle repeats, as shown in Figure 11 as
long as the short-circuit-condition persists. This mode of operation helps to reduce the temperature rise of the
device during a hard short on the output. The output current is greatly reduced during hiccup mode (see Typical
Characteristics). Once the output short is removed, and the hiccup delay is passed, the output voltage recovers
normally as shown in Figure 12
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Feature Description (continued)
Short Applied
Short Removed
VOUT, 2V/Div
Inductor Current, 1A/Div
50ms/Div
Inductor Current,
1A/Div
50ms/Div
Figure 11. Inductor Current Burst in Short-Circuit Mode
Figure 12. Short-Circuit Transient and Recovery
8.3.4 Undervoltage Lockout and Thermal Shutdown
The LMR33620-Q1 incorporates an undervoltage-lockout feature on the output of the internal LDO (at the VCC
pin). When VCC reaches about 3.7 V the device is ready to receive an EN signal and start up. When VCC falls
below about 3 V the device shuts down, regardless of EN status. Because the LDO is in dropout during these
transitions, the above values roughly represent the input voltage levels during the transitions.
Thermal shutdown is provided to protect the regulator from excessive junction temperature. When the junction
temperature reaches about 165°C the device shuts down; re-start occurs when the temperature falls to about
148°C.
8.4 Device Functional Modes
8.4.1 Auto Mode
In auto mode the device moves between PWM and PFM as the load changes. At light loads the regulator
operates in PFM. At higher loads the mode changes to PWM. The load current for which the device moves from
PFM to PWM can be found in the Application Curves. The output current at which the device changes modes
depends on the input voltage, inductor value and the nominal switching frequency. For output currents above the
curve, the device is in PWM mode. For currents below the curve, the device is in PFM. The curves apply for a
nominal switching frequency of 400 kHz and the BOM shown in Table 3. At higher switching frequencies the load
at which the mode change occurs will be greater. For applications where the switching frequency must be known
for a given condition, the transition between PFM and PWM must be carefully tested before the design is
finalized.
In PWM mode the regulator operates as a constant frequency converter using PWM to regulate the output
voltage. While operating in this mode the output voltage is regulated by switching at a constant frequency and
modulating the duty cycle to control the power to the load. This provides excellent line and load regulation and
low output voltage ripple.
In PFM the high-side MOSFET is turned on in a burst of one or more pulses to provide energy to the load. The
duration of the burst depends on how long it takes the inductor current to reach IPEAK-MIN. The periodicity of these
bursts is adjusted to regulate the output, while diode emulation (DEM) is used to maximize efficiency (see
Glossary). This mode provides high light-load efficiency by reducing the amount of input supply current required
to regulate the output voltage at light loads. PFM results in very good light-load efficiency, but also yields larger
output voltage ripple and variable switching frequency. Also, a small increase in output voltage occurs at light
loads. The actual switching frequency and output voltage ripple depends on the input voltage, output voltage,
and load. Typical switching waveforms in PFM and PWM are shown in Figure 13 and Figure 14. See the
Application Curves for output voltage variation with load in auto mode.
16
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Device Functional Modes (continued)
SW,
5V/Div
SW,
5V/Div
VOUT,
10mV/Div
VOUT,
10mV/Div
Inductor
Current,
1A/Div
Inductor
Current,
0.5A/Div
2µs/Div
50µs/Div
Figure 14. Typical PWM Switching Waveforms
VIN = 12 V, VOUT = 5 V, IOUT = 2 A, ƒS = 400 kHz
Figure 13. Typical PFM Switching Waveforms
VIN = 12 V, VOUT = 5 V, IOUT = 10 mA
8.4.2 Dropout
6
0.3
5.5
0.25
Drop-out Voltage (V)
Output Voltage (V)
The dropout performance of any buck regulator is affected by the RDSON of the power MOSFETs, the DC
resistance of the inductor, and the maximum duty cycle that the controller can achieve. As the input voltage level
approaches the output voltage, the off-time of the high side MOSFET starts to approach the minimum value (see
Timing Characteristics). Beyond this point the switching may become erratic, and/or the output voltage falls out of
regulation. To avoid this problem the LMR33620-Q1 automatically reduces the switching frequency to increase
the effective duty cycle and maintain regulation. In this data sheet the dropout voltage is defined as the
difference between the input and output voltage when the output has dropped by 1% of its nominal value. Under
this condition the switching frequency has dropped to its minimum value of about 140 kHz. Note that the 0.4 V
short circuit detection threshold is not activated when in dropout mode. Typical drop-out characteristics can be
found in Figure 15, Figure 16, Figure 17, and Figure 18.
5
4.5
4
0A
3.5
5
5.5
6
6.5
Input Voltage (V)
0.1
3.3V
5V
2A
0
3
4.5
0.15
0.05
1A
4
0.2
7
0
Figure 15. Overall Dropout Characteristic
VOUT = 5 V
0.5
1
1.5
2
Output Current (A)
C002
2.5
C001
Figure 16. Typical Dropout Voltage vs Output Current in
Frequency Foldback
ƒSW = 140 kHz
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2.4
2.4
2.2
2.2
2
Switching Frequency (MHz)
Switching Frequency (MHz)
Device Functional Modes (continued)
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
1A
0.2
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
1A
0.2
2A
0
2A
0
3.5
4
4.5
5
5.5
6
6.5
Input Voltage (V)
7
7.5
8
3.5
4
4.5
5
5.5
6
6.5
7
7.5
Input Voltage (V)
C029
Figure 17. Typical Switching Frequency in Dropout Mode
VOUT = 3.3 V, fSW = 2.1 MHz
8
8.5
9
9.5 10
C028
Figure 18. Typical Switching Frequency in Dropout Mode
VOUT = 5 V, fSW = 2.1 MHz
8.4.3 Minimum Switch On-Time
Every switching regulator has a minimum controllable on-time dictated by the inherent delays and blanking times
associated with the control circuits. This imposes a minimum switch duty cycle and therefore a minimum
conversion ratio. The constraint is encountered at high input voltages and low output voltages. To help extend
the minimum controllable duty cycle, the LMR33620-Q1 automatically reduces the switching frequency when the
minimum on-time limit is reached. In this way the converter can regulate the lowest programmable output voltage
at the maximum input voltage. An estimate for the approximate input voltage, for a given output voltage, before
frequency foldback occurs is found in Equation 2. The values of tON and fSW can be found in the Electrical
Characteristics table. As the input voltage is increased, the switch on-time (duty-cycle) reduces to regulate the
output voltage. When the on-time reaches the limit, the switching frequency drops, while the on-time remains
fixed. This relationship is highlighted in Figure 19 for a nominal switching frequency of 2.1 MHz.
VOUT
VIN d
t ON ˜ fSW
(2)
2.6
Switching Frequency (MHz)
2.4
2.2
2
1.8
1.6
1.4
1A
1.2
2A
1
10 12 14 16 18 20 22 24 26 28 30 32 34 36 38
Input Voltage (V)
C027
Figure 19. Switching Frequency vs Input Voltage
VOUT = 3.3 V,
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9 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
NOTE
In this data sheet the effective value of capacitance is defined as the actual capacitance
under D.C. bias and temperature; not the rated or nameplate values. Use high-quality,
low-ESR, ceramic capacitors with an X5R or better dielectric throughout. All high value
ceramic capacitors have a large voltage coefficient in addition to normal tolerances and
temperature effects. Under D.C. bias the capacitance drops considerably. Large case
sizes and/or higher voltage ratings are better in this regard. To help mitigate these effects,
multiple capacitors can be used in parallel to bring the minimum effective capacitance up
to the required value. This can also ease the RMS current requirements on a single
capacitor. A careful study of bias and temperature variation of any capacitor bank should
be made in order to ensure that the minimum value of effective capacitance is provided.
9.1 Application Information
The LMR33620-Q1 step-down DC-to-DC converter is typically used to convert a higher DC voltage to a lower DC
voltage with a maximum output current of 2 A. The following design procedure can be used to select components
for the LMR33620-Q1. Alternately, the WEBENCH Design Tool may be used to generate a complete design.
This tool utilizes an iterative design procedure and has access to a comprehensive database of components.
This allows the tool to create an optimized design and allows the user to experiment with various options.
9.2 Typical Application
Figure 20 shows a typical application circuit for the LMR33620-Q1. This device is designed to function over a
wide range of external components and system parameters. However, the internal compensation is optimized for
a certain range of external inductance and output capacitance. As a quick start guide, Table 2 provides typical
component values for a range of the most common output voltages. The values given in the table are typical.
Other values may be used to enhance certain performance criterion as required by the application. When using
the fixed output voltage version, connect the FB input directly to VOUT. Note that for the VQFN package, the input
capacitors are split and placed on either side of the package; see the Input Capacitor Selection section for more
details.
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Typical Application (continued)
L
VIN
6 V to 36 V
VOUT
SW
VIN
5V
2A
10 µH
CIN
CHF
10 µF
CBOOT
220 nF
COUT
BOOT
EN
4x 22 µF
0.1 µF
RFBT
CFF
PG
100 NŸ
PG
100 NŸ
VCC
CVCC
1 µF
FB
PGND
AGND
RFBB
24.9 NŸ
Figure 20. Example Application Circuit (400 kHz)
9.2.1 Design Requirements
Table 1 provides the parameters for our detailed design procedure example:
Table 1. Detailed Design Parameters
DESIGN PARAMETER
EXAMPLE VALUE
Input voltage
12 V (6 V to 36 V)
Output voltage
5V
Maximum output current
0 A to 2 A
Switching frequency
400 kHz
Table 2. Typical External Component Values
ƒSW
(kHz)
VOUT (V)
L (µH)
COUT (rated
capacitance)
RFBT (Ω)
RFBB (Ω)
CIN + CHF
CBOOT
CVCC
CFF
400
3.3
10
4 × 22 µF
100 k
43.2 k
10 µF + 220 nF
100 nF
1 µF
open
1400
3.3
2.2
2 × 22 µF
100 k
43.2 k
10 µF + 220 nF
100 nF
1 µF
open
2100
3.3
1.2
2 × 22 µF
100 k
43.2 k
10 µF + 220 nF
100 nF
1 µF
open
400
5
10
4 × 22 µF
100 k
24.9 k
10 µF + 220 nF
100 nF
1 µF
open
1400
5
2.2
2 × 22 µF
100 k
24.9 k
10 µF + 220 nF
100 nF
1 µF
open
2100
5
1.5
2 × 22 µF
100 k
24.9 k
10 µF + 220 nF
100 nF
1 µF
open
400
12
27
4 × 22 µF
100 k
9.09 k
10 µF + 220 nF
100 nF
1 µF
open
1400
12
4.7
4 × 10 µF
100 k
9.09 k
10 µF + 220 nF
100 nF
1 µF
open
2100
12
3.3
4 × 10 µF
100 k
9.09 k
10 µF + 220 nF
100 nF
1 µF
open
20
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9.2.2 Detailed Design Procedure
The following design procedure applies to Figure 20 and Table 1.
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9.2.2.1 Custom Design With WEBENCH® Tools
Click here to create a custom design using the LMR33620-Q1 device with the WEBENCH® Power Designer.
1. Start by entering the input voltage (VIN), output voltage (VOUT), and output current (IOUT) requirements.
2. Optimize the design for key parameters such as efficiency, footprint, and cost using the optimizer dial.
3. Compare the generated design with other possible solutions from Texas Instruments.
The WEBENCH Power Designer provides a customized schematic along with a list of materials with real-time
pricing and component availability.
In most cases, these actions are available:
• Run electrical simulations to see important waveforms and circuit performance
• Run thermal simulations to understand board thermal performance
• Export customized schematic and layout into popular CAD formats
• Print PDF reports for the design, and share the design with colleagues
Get more information about WEBENCH tools at www.ti.com/WEBENCH.
9.2.2.2 Choosing the Switching Frequency
The choice of switching frequency is a compromise between conversion efficiency and overall solution size.
Lower switching frequency implies reduced switching losses and usually results in higher system efficiency.
However, higher switching frequency allows the use of smaller inductors and output capacitors, and hence a
more compact design. For this example we choose 400 kHz.
9.2.2.3 Setting the Output Voltage
The output voltage of LMR33620-Q1 is externally adjustable using a resistor divider network. The range of
recommended output voltage is found in the Recommended Operating Conditions table. The divider network is
comprised of RFBT and RFBB, and closes the loop between the output voltage and the converter. The converter
regulates the output voltage by holding the voltage on the FB pin equal to the internal reference voltage, VREF.
The resistance of the divider is a compromise between excessive noise pick-up and excessive loading of the
output. Smaller values of resistance reduce noise sensitivity but also reduce the light-load efficiency. The
recommended value for RFBT is 100 kΩ; with a maximum value of 1 MΩ. If a 1 MΩ is selected for RFBT, then a
feed-forward capacitor must be used across this resistor to provide adequate loop phase margin (see CFF
Selection). Once RFBT is selected, Equation 3 is used to select RFBB. VREF is nominally 1 V (see Electrical
Characteristics for limits).
RFBT
RFBB
ª VOUT
º
1»
«
V
¬ REF
¼
(3)
For this 5-V example, RFBT = 100 kΩ and RFBB = 24.9 kΩ are chosen.
9.2.2.3.1 Fixed Output Voltage Option
With the fixed output voltage version, the feed-back divider is internal to the device. Therefore, an external
divider is not needed and the FB input is connected directly to VOUT. The total resistance of the internal divider is
about 2 MΩ (see Electrical Characteristics). The large value of the divider reduces the loading on the output and
helps to reduce the no-load input current of the system. For those applications that require the lowest no-load
input current, without resorting to large value feed-back resistors, the fixed output voltage option is a good
solution. Figure 21 and Figure 22 show the no-load and light load input supply current for the fixed option, using
the BOM from Table 2 and with RFBT = 0 Ω and RFBB = open. Figure 23 and Figure 24 show the same
characteristics for the 3.3-V fixed option.
22
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28
0.01
26
Input Current (A)
Input Current (µA)
27
25
24
23
0.001
0.0001
8V
22
12V
21
5V
18V
20
5
10
15
20
25
30
35
Input Voltage (V)
0.00001
0.00001
40
0.0001
0.001
0.01
Output Current (A)
C004
Figure 21. No-load Input Supply Current for 5-V Fixed
Output Option
C001
Figure 22. Input Supply Current vs Output Current for 5-V
Fixed Output Option
28
0.01
26
Input Current (A)
Input Current (µA)
27
25
24
23
0.001
0.0001
5V
22
12V
21
18V
3.3V
20
5
10
15
20
25
30
Input Voltage (V)
35
40
0.00001
0.00001
Figure 23. No-load Input Supply Current for 3.3-V Fixed
Output Option
0.0001
0.001
Output Current (A)
C003
0.01
C002
Figure 24. Input Supply Current vs Output Current for 3.3V Fixed Output Option
9.2.2.4 Inductor Selection
The parameters for selecting the inductor are the inductance and saturation current. The inductance is based on
the desired peak-to-peak ripple current and is normally chosen to be in the range of 20% to 40% of the maximum
output current. Experience shows that the best value for inductor ripple current is 30% of the maximum load
current. Note that when selecting the ripple current for applications with much smaller maximum load than the
maximum available from the device, the maximum device current should be used. Equation 4 can be used to
determine the value of inductance. The constant K is the percentage of inductor current ripple. For this example
we choose K = 0.3 and find an inductance ; we select the next standard value of 10 µH.
L
VIN VOUT
V
˜ OUT
fSW ˜ K ˜ IOUT max VIN
(4)
Ideally, the saturation current rating of the inductor should be at least as large as the high-side switch current
limit, ISC (see Electrical Characteristics ). This ensures that the inductor does not saturate even during a short
circuit on the output. When the inductor core material saturates, the inductance falls to a very low value, causing
the inductor current to rise very rapidly. Although the valley current limit, ILIMIT, is designed to reduce the risk of
current run-away, a saturated inductor can cause the current to rise to high values very rapidly. This may lead to
component damage; do not allow the inductor to saturate! Inductors with a ferrite core material have very hard
saturation characteristics, but usually have lower core losses than powdered iron cores. Powered iron cores
exhibit a soft saturation, allowing some relaxation in the current rating of the inductor. However, they have more
core losses at frequencies typically above 1 MHz. In any case the inductor saturation current should not be less
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than the device low-side current limit, ILIMIT (see Electrical Characteristics). In order to avoid sub-harmonic
oscillation, the inductance value should not be less than that given in Equation 5. The maximum inductance is
limited by the minimum current ripple required for the current mode control to perform correctly. As a rule-ofthumb, the minimum inductor ripple current should be no less than about 10% of the device maximum rated
current under nominal conditions.
V
LMIN t 0.36 ˜ OUT
fSW
(5)
9.2.2.5 Output Capacitor Selection
The value of the output capacitor, and its ESR, determine the output voltage ripple and load transient
performance. The output capacitor bank is usually limited by the load transient requirements, rather than the
output voltage ripple. Equation 6 can be used to estimate a lower bound on the total output capacitance, and an
upper bound on the ESR, required to meet a specified load transient.
º
ª
'IOUT
K2
COUT t
˜«1 D ˜ 1 K
˜ 2 D»
12
fSW ˜ 'VOUT ˜ K ¬«
¼»
ESR d
D
2 K ˜ 'VOUT
ª
K2 §
1 ·º
¸»
˜ ¨¨1
2 ˜ 'IOUT «1 K
12 © (1 D) ¸¹¼»
¬«
VOUT
VIN
where
•
•
•
ΔVOUT = output voltage transient
ΔIOUT = output current transient
K = Ripple factor from Inductor Selection
(6)
Once the output capacitor and ESR have been calculated, Equation 7 can be used to check the peak-to-peak
output voltage ripple; Vr.
Vr # 'IL ˜ ESR 2
1
8 ˜ fSW ˜ COUT
2
(7)
The output capacitor and ESR can then be adjusted to meet both the load transient and output ripple
requirements.
For this example we require a ΔVOUT of ≤ 250 mV for an output current step of ΔIOUT = 2 A. Equation 6 gives a
minimum value of 45 µF and a maximum ESR of 0.11 Ω. Assuming a 20% tolerance and a 10% bias de-rating,
we arrive at a minimum capacitance of 63 µF. This can be achieved with a bank of 4 × 22-µF, 16-V, ceramic
capacitors in the 1210 case size. More output capacitance can be used to improve the load transient response.
Ceramic capacitors can easily meet the minimum ESR requirements. In some cases an aluminum electrolytic
capacitor can be placed in parallel with the ceramics to help build up the required value of capacitance. In
general use a capacitor of at least 10 V for output voltages of 3.3 V or less, while a capacitor of 16 V or more
should be used for output voltages of 5 V and above.
In practice the output capacitor has the most influence on the transient response and loop phase margin. Load
transient testing and Bode plots are the best way to validate any given design and should always be completed
before the application goes into production. In addition to the required output capacitance, a small ceramic
placed on the output can help to reduce high frequency noise. Small case size ceramic capacitors in the range of
1 nF to 100 nF can be very helpful in reducing voltage spikes on the output caused by inductor and board
parasitics.
24
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The maximum value of total output capacitance should be limited to about 10 times the design value, or 1000 µF,
whichever is smaller. Large values of output capacitance can adversely affect the start-up behavior of the
regulator as well as the loop stability. If values larger than noted here must be used, then a careful study of startup at full load and loop stability must be performed.
9.2.2.6 Input Capacitor Selection
The ceramic input capacitors provide a low impedance source to the regulator in addition to supplying the ripple
current and isolating switching noise from other circuits. A minimum of 10 µF of ceramic capacitance is required
on the input of the LMR33620-Q1. This must be rated for at least the maximum input voltage that the application
requires; preferably twice the maximum input voltage. This capacitance can be increased to help reduce input
voltage ripple and/or maintain the input voltage during load transients. In addition a small case size 220-nF
ceramic capacitor must be used at the input, as close a possible to the regulator. This provides a high frequency
bypass for the control circuits internal to the device. For this example a 10-µF, 50-V, X7R (or better) ceramic
capacitor is chosen. The 220 nF must also be rated at 50 V with an X7R dielectric. The VQFN (RNX) package
provides two input voltage pins and two power ground pins on opposite sides of the package. This allows the
input capacitors to be split, and placed optimally with respect to the internal power MOSFETs, thus improving the
effectiveness of the input bypassing. In this example, place two 4.7-µF and two 100-nF ceramic capacitors at
each VIN/PGND location. A single 10-µF can also be used on one side of the package.
Many times it is desirable to use an electrolytic capacitor on the input in parallel with the ceramics. This is
especially true if long leads/traces are used to connect the input supply to the regulator. The moderate ESR of
this capacitor can help damp any ringing on the input supply caused by the long power leads. The use of this
additional capacitor also helps with momentary voltage dips caused by input supplies with unusually high
impedance.
Most of the input switching current passes through the ceramic input capacitor(s). The approximate worst case
RMS value of this current can be calculated from Equation 8 and should be checked against the manufacturers'
maximum ratings.
I
IRMS # OUT
2
(8)
9.2.2.7 CBOOT
The LMR33620-Q1 requires a boot-strap capacitor connected between the BOOT pin and the SW pin. This
capacitor stores energy that is used to supply the gate drivers for the power MOSFETs. A high-quality ceramic
capacitor of 100 nF and at least 10 V is required.
9.2.2.8 VCC
The VCC pin is the output of the internal LDO used to supply the control circuits of the regulator. This output
requires a 1-µF, 16-V ceramic capacitor connected from VCC to GND for proper operation. In general avoid
loading this output with any external circuitry. However, this output can be used to supply the pull-up for the
power-good function (see Power-Good Flag Output). A value of 100 kΩ is a good choice in this case. The
nominal output voltage on VCC is 5 V; see Electrical Characteristics for limits. Do not short this output to ground
or any other external voltage.
9.2.2.9 CFF Selection
In some cases a feed-forward capacitor can be used across RFBT to improve the load transient response or
improve the loop-phase margin. This is especially true when values of RFBT > 100 kΩ are used. Large values of
RFBT, in combination with the parasitic capacitance at the FB pin, can create a small signal pole that interferes
with the loop stability. A CFF can help to mitigate this effect. Equation 9 can be used to estimate the value of CFF.
The value found with Equation 9 is a starting point; use lower values to determine if any advantage is gained by
the use of a CFF capacitor. The application report Optimizing Transient Response of Internally Compensated DCDC Converters with Feed-forward Capacitor is helpful when experimenting with a feed-forward capacitor.
VOUT ˜ COUT
CFF
VREF
120 ˜ RFBT ˜
VOUT
(9)
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9.2.2.10 External UVLO
In some cases an input UVLO level different than that provided internal to the device is needed. This can be
accomplished by using the circuit shown in Figure 25. The input voltage at which the device turns on is
designated VON; while the turnoff voltage is VOFF. First a value for RENB is chosen in the range of 10 kΩ to 100
kΩ and then Equation 10 is used to calculate RENT and VOFF.
VIN
RENT
EN
RENB
Figure 25. Set-Up for External UVLO Application
R ENT
§ V ON
¨¨
© VEN H
·
1¸¸ ˜ R ENB
¹
V OFF
§
V ON ˜ ¨¨ 1
©
VEN HYS
VEN H
·
¸¸
¹
where
•
•
VON = VIN turnon voltage
VOFF = VIN turnoff voltage
(10)
9.2.2.11 Maximum Ambient Temperature
As with any power conversion device, the LMR33620-Q1 dissipates internal power while operating. The effect of
this power dissipation is to raise the internal temperature of the converter above ambient. The internal die
temperature (TJ) is a function of the ambient temperature, the power loss and the effective thermal resistance,
RθJA of the device and PCB combination. The maximum internal die temperature for the LMR33620-Q1 must be
limited to 125°C. This establishes a limit on the maximum device power dissipation and therefore the load
current. Equation 11 shows the relationships between the important parameters. It is easy to see that larger
ambient temperatures (TA) and larger values of RθJA reduce the maximum available output current. The converter
efficiency can be estimated by using the curves provided in this data sheet. If the desired operating conditions
can not be found in one of the curves, then interpolation can be used to estimate the efficiency. Alternatively, the
EVM can be adjusted to match the desired application requirements and the efficiency can be measured directly.
The correct value of RθJA is more difficult to estimate. As stated in Semiconductor and IC Package Thermal
Metrics, the value of RθJA given in the Thermal Information table is not valid for design purposes and must not be
used to estimate the thermal performance of the application. The values reported in that table were measured
under a specific set of conditions that are rarely obtained in an actual application.
IOUT
MAX
TJ TA
1
K
˜
˜
R TJA
1 K VOUT
where
•
η = Efficiency
(11)
The effective RθJA is a critical parameter and depends on many factors such as power dissipation, air
temperature/flow, PCB area, copper heat-sink area, number of thermal vias under the package, and adjacent
component placement; to mention just a few. Due to the ultra-miniature size of the VQFN (RNX) package, a DAP
is not available. This means that this package exhibits a somewhat large value RθJA. A typical example of RθJA vs
copper board area can be found in Figure 26. The copper area given in the graph is for each layer; the top and
bottom layers are 2 oz. copper each, while the inner layers are 1 oz. A typical curve of maximum output current
vs. ambient temperature is shown in Figure 27. This data was taken with a device/PCB combination giving an
RθJA of about 50°C/W. It must be remembered that the data given in these graphs are for illustration purposes
only, and the actual performance in any given application depends on all of the previously mentioned factors.
26
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2.5
70
Maximum Output Current (A)
60
55
R
JA (ƒC/w)
65
50
45
2
1.5
1
0.5
RNX, 4L
40
0
10
20
30
40
50
60
0
70
Copper Area (cm2)
0
10 20 30 40 50 60 70 80 90 100 110 120 130 140
C005
Ambient Termperature (ƒC)
C007
VIN = 12 V
ƒSW = 400 kHz
VOUT = 5 V
RθJA = 50°C/W
Figure 27. Maximum Output Current vs Ambient
Temperature
Figure 26. RθJA vs Copper Board Area for the VQFN (RNX)
Package
Use the following resources as a guide to optimal thermal PCB design and estimating RθJA for a given application
environment:
• Thermal Design by Insight not Hindsight
• A Guide to Board Layout for Best Thermal Resistance for Exposed Pad Packages
• Semiconductor and IC Package Thermal Metrics
• Thermal Design Made Simple with LM43603 and LM43602
• SLMA002 PowerPADTM Thermally Enhanced Package
• PowerPADTM Made Easy
• SBVA025 Using New Thermal Metrics
9.2.3 Application Curves
100
100
95
95
90
90
85
85
Efficiency (%)
Efficiency (%)
Unless otherwise specified the following conditions apply: VIN = 12 V, TA = 25°C. The circuit is shown in
Figure 52, with the appropriate BOM from Table 3. EMI results depend critically on PCB layout and test set-up.
Submit any inquiries regarding the EMI data to E2E.com.
80
75
70
8V
65
0.01
0.1
Output Current (A)
VOUT = 5 V
400 kHz
1
5V
12V
24V
55
36V
50
0.001
70
60
24V
55
75
65
12V
60
80
10
50
0.001
0.01
0.1
1
10
Output Current (A)
C018
RNX Package
36V
VOUT = 3.3 V
Figure 28. Efficiency
400 kHz
C019
RNX Package
Figure 29. Efficiency
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100
100
95
95
90
90
85
85
Efficiency (%)
Efficiency (%)
SNVSB27B – JUNE 2018 – REVISED MARCH 2019
80
75
70
8V
65
80
75
70
60
0.01
0.1
1
VOUT = 5 V
36V
50
0.001
10
Output Current (A)
24V
55
36V
50
0.001
12V
60
24V
55
5V
65
12V
0.01
1.4 MHz
RNX Package
VOUT = 3.3 V
100
100
95
95
90
90
85
85
80
75
70
8V
65
60
55
1
80
75
70
5V
12V
24V
36V
50
0.001
10
Output Current (A)
0.01
RNX Package
VOUT = 3.3 V
1
10
C023
2.1 MHz
Figure 32. Efficiency
RNX Package
Figure 33. Efficiency
34
5.055
8V
5.045
12V
5.04
24V
5.035
36V
32
Input Supply Current (µA)
5.05
Output Voltage (V)
0.1
Output Current (A)
C020
2.1 MHz
RNX Package
55
36V
VOUT = 5 V
C021
1.4 MHz
60
24V
0.1
10
65
12V
0.01
1
Figure 31. Efficiency
Efficiency (%)
Efficiency (%)
Figure 30. Efficiency
50
0.001
0.1
Output Current (A)
C022
5.03
5.025
5.02
5.015
5.01
30
28
26
24
22
5.005
5V
5
20
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Output Current (A)
1.8
2
5
10
VOUT = 5 V
15
20
25
30
Input Voltage (V)
C011
VOUT = 5 V
RFBT = 1 MΩ
35
40
C016
IOUT = 0 A
Figure 34. Line and Load Regulation
Figure 35. Input Supply Current
28
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0.25
Switching Frequency (kHz)
10000
0.15
X
PWM
0.1
PFM
X
Output Current (A)
0.2
0.05
1000
100
10
8V
1
12V
5V
0
0
5
10
15
20
25
30
35
40
Input Voltage (V)
VOUT = 5 V
18V
0.1
0.00001
0.0001
0.001
ƒSW = 400 kHz
0.01
0.1
1
10
Output Current (A)
C005
VOUT = 5 V
Figure 36. Mode Change Thresholds
C025
ƒSW = 2100 kHz
Figure 37. Switching Frequency vs Output Current
VOUT,
300mV/Div
VOUT,
300mV/Div
Output Current,
0.5A/Div
Output Current,
0.5A/Div
100µs/Div
VIN = 12 V
tf = tr = 2 µs
VOUT = 5 V
IOUT = 0 A to 2 A
100µs/Div
VIN = 12 V
tf = tr = 2 µs
VOUT = 5 V
IOUT = 1 A to 2 A
Figure 39. Load Transient
Figure 38. Load Transient
34
3.345
5V
32
12V
24V
3.33
36V
Input Supply Current (µA)
Output Voltage (V)
3.34
3.335
3.325
3.32
3.315
30
28
26
24
3.31
22
3.305
20
3.3V
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Output Current (A)
1.8
2
5
10
VOUT = 3.3 V
15
20
25
30
35
Input Voltage (V)
C012
VOUT = 3.3 V
Figure 40. Line and Load Regulation
IOUT = 0 A
C015
RFBT = 1 MΩ
Figure 41. Input Supply Current
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0.35
10000
Switching Frequency (kHz)
Output Current (A)
0.30
0.25
0.20
X
0.15
PWM
0.10
PFM
X
0.05
1000
100
10
5V
1
12V
3.3V
0.00
0
5
10
15
20
25
30
35
Input Voltage (V)
VOUT = 3.3V
18V
40
0.1
0.00001
ƒSW = 400 kHz
0.001
0.01
0.1
1
Output Current (A)
VOUT = 3.3 V
Figure 42. Mode Change Thresholds
ƒSW = 2100 kHz
10
C026
L = 1.2 µH
Figure 43. Switching Frequency vs Output Current
VOUT,
300mV/Div
VOUT,
300mV/Div
Output Current,
0.5A/Div
Output Current,
0.5A/Div
0
100µs/Div
VIN = 12 V
tf = tr = 2 µs
VOUT = 3.3 V
IOUT = 0 A to 2 A
100µs/Div
VIN = 12 V
tf = tr = 2 µs
VIN = 12 V
ƒSW = 400 kHz
VOUT = 5 V
VOUT = 3.3 V
IOUT = 1 A to 2 A
Figure 45. Load Transient
Figure 44. Load Transient
IOUT = 3 A
RNX package
VIN = 12 V
ƒSW = 400 kHz
VOUT = 5 V
IOUT = 3 A
RNX package
Figure 47. Radiated EMI
Biconical Antenna (Horizontal)
Figure 46. Conducted EMI
30
0.0001
C006
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VIN = 12 V
ƒSW = 400 kHz
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VOUT = 5 V
IOUT = 3 A
RNX package
VIN = 12 V
ƒSW = 400 kHz
Figure 48. Radiated EMI
Biconical Antenna (Vertical)
VIN = 12 V
ƒSW = 400 kHz
VOUT = 5 V
VOUT = 5 V
IOUT = 3 A
RNX package
Figure 49. Radiated EMI
Log-periodic Antenna (Horizontal)
IOUT = 3 A
RNX package
VIN = 12 V
ƒSW = 400 kHz
Figure 50. Radiated EMI
Log-periodic Antenna (Vertical)
VOUT = 5 V
IOUT = 3 A
RNX package
Figure 51. Radiated EMI
Rod Antenna
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L
VIN
VIN
VOUT
SW
U1
CBOOT
CIN
CHF
COUT
BOOT
EN
0.1 µF
RFBT
PG
100 NŸ
PG
100 NŸ
VCC
CVCC
1 µF
FB
PGND
AGND
RFBB
Figure 52. Circuit for Application Curves
Table 3. BOM for Typical Application Curves RNX Package (1)
(1)
VOUT
FREQUENCY
RFBB
COUT
CIN + CHF
L
U1
3.3 V
400 kHz
43.3 kΩ
4 × 22 µF
2 × 4.7 µF + 2 × 100 nF
4.7 µH, 28 mΩ
LMR33620ARNX
3.3 V
1400 KHz
43.3 kΩ
4 × 22 µF
2 × 4.7 µF + 2 × 100 nF
2.2 µH, 11.4 mΩ
LMR33620BRNX
3.3 V
2100 kHz
43.3 kΩ
4 × 22 µF
2 × 4.7 µF + 2 × 100 nF
2.2 µH, 11.4 mΩ
LMR33620CRNX
5V
400 kHz
24.9 kΩ
4 × 22 µF
2 × 4.7 µF + 2 × 100 nF
6.8 µH, 14 mΩ
LMR33620ARNX
5V
1400 KHz
24.9 kΩ
4 × 22 µF
2 × 4.7 µF + 2 × 100 nF
2.2 µH, 11.4 mΩ
LMR33620BRNX
5V
2100 kHz
24.9 kΩ
4 × 22 µF
2 × 4.7 µF + 2 × 100 nF
2.2 µH, 11.4 mΩ
LMR33620CRNX
The values in this table were selected to enhance certain performance criteria and may not represent typical values.
+
100µF
0.1µF
4.7µF
3.3µF
2x 0.1µF
3x 4.7µF
2x 0.1µF
Input Supply
2x 4.7µF
Ferrite Bead
Input to
Regulator
Figure 53. Typical Input EMI Filter
Filter used only for EMI measurements found in Application Curves
9.3 Do's and Don'ts
•
•
•
•
•
•
•
32
Don't: Exceed the Absolute Maximum Ratings
Don't: Exceed the ESD Ratings
Don't: Exceed the Recommended Operating Conditions
Don't: Allow the EN input to float.
Don't: Allow the output voltage to exceed the input voltage, nor go below ground.
Don't: Use the value of RθJA given in the table to design your application. Us the information in the Maximum
Ambient Temperature section.
Do: Follow all the guidelines and/or suggestions found in this data sheet before committing the design to
production. TI application engineers are ready to help critique your design and PCB layout to help make your
project a success (see Community Resources).
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10 Power Supply Recommendations
The characteristics of the input supply must be compatible with the Absolute Maximum Ratings and
Recommended Operating Conditions found in this data sheet. In addition, the input supply must be capable of
delivering the required input current to the loaded regulator. The average input current can be estimated with
Equation 12, where η is the efficiency.
VOUT ˜ IOUT
IIN
VIN ˜ K
(12)
If the regulator is connected to the input supply through long wires or PCB traces, special care is required to
achieve good performance. The parasitic inductance and resistance of the input cables can have an adverse
effect on the operation of the regulator. The parasitic inductance, in combination with the low-ESR, ceramic input
capacitors, can form an under damped resonant circuit, resulting in overvoltage transients at the input to the
regulator. The parasitic resistance can cause the voltage at the VIN pin to dip whenever a load transient is
applied to the output. If the application is operating close to the minimum input voltage, this dip may cause the
regulator to momentarily shutdown and/or reset. The best way to solve these kind of issues is to reduce the
distance from the input supply to the regulator and/or use an aluminum or tantalum input capacitor in parallel with
the ceramics. The moderate ESR of these types of capacitors help to damp the input resonant circuit and reduce
any overshoots. A value in the range of 20 µF to 100 µF is usually sufficient to provide input damping and help to
hold the input voltage steady during large load transients.
Sometimes, for other system considerations, an input filter is used in front of the regulator. This can lead to
instability, as well as some of the effects mentioned above, unless it is designed carefully. The user guide AN2162 Simple Success With Conducted EMI From DCDC Converters provides helpful suggestions when
designing an input filter for any switching regulator.
In some cases a transient voltage suppressor (TVS) is used on the input of regulators. One class of this device
has a snap-back characteristic (thyristor type). The use of a device with this type of characteristic is not
recommended. When the TVS fires, the clamping voltage falls to a very low value. If this voltage is less than the
output voltage of the regulator, the output capacitors discharge through the device back to the input. This
uncontrolled current flow may damage the device.
The input voltage should not be allowed to fall below the output voltage. In this scenario, such as a shorted input
test, the output capacitors will discharge through the internal parasitic diode found between the VIN and SW pins
of the device. During this condition, the current can become uncontrolled, possibly causing damage to the
device. If this scenario is considered likely, then a Schottky diode between the input supply and the output should
be used.
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11 Layout
11.1 Layout Guidelines
The PCB layout of any DC/DC converter is critical to the optimal performance of the design. Bad PCB layout can
disrupt the operation of an otherwise good schematic design. Even if the converter regulates correctly, bad PCB
layout can mean the difference between a robust design and one that cannot be mass produced. Furthermore,
the EMI performance of the regulator is dependent on the PCB layout, to a great extent. In a buck converter the
most critical PCB feature is the loop formed by the input capacitor(s) and power ground, as shown in Figure 54.
This loop carries large transient currents that can cause large transient voltages when reacting with the trace
inductance. These unwanted transient voltages will disrupt the proper operation of the converter. Because of this,
the traces in this loop should be wide and short, and the loop area as small as possible to reduce the parasitic
inductance. Figure 55 shows a recommended layout for the critical components of the LMR33620-Q1.
1. Place the input capacitor(s) as close as possible to the VIN and GND terminals. VIN and GND pins are
adjacent, simplifying the input capacitor placement. With the VQFN package there are two VIN/PGND pairs
on either side of the package. This provides for a symmetrical layout and helps to minimize switching noise
and EMI generation. A wide VIN plane should be used on a lower layer to connect both of the VIN pairs
together to the input supply; see Figure 55.
2. Place bypass capacitor for VCC close to the VCC pin. This capacitor must be placed close to the device
and routed with short, wide traces to the VCC and GND pins.
3. Use wide traces for the CBOOT capacitor. Place CBOOT close to the device with short/wide traces to the
BOOT and SW pins. It is important to route the SW connection under the device to the NC pin, and use this
path to connect the BOOT capacitor to SW.
4. Place the feedback divider as close as possible to the FB pin of the device. Place RFBB, RFBT, and CFF,
if used, physically close to the device. The connections to FB and GND must be short and close to those
pins on the device. The connection to VOUT can be somewhat longer. However, this latter trace must not be
routed near any noise source (such as the SW node) that can capacitively couple into the feedback path of
the regulator.
5. Use at least one ground plane in one of the middle layers. This plane acts as a noise shield and also act
as a heat dissipation path.
6. Provide wide paths for VIN, VOUT, and GND. Making these paths as wide and direct as possible reduces
any voltage drops on the input or output paths of the converter and maximizes efficiency.
7. Provide enough PCB area for proper heat sinking. As stated in the Maximum Ambient Temperature
section, enough copper area must be used to ensure a low RθJA, commensurate with the maximum load
current and ambient temperature. Make the top and bottom PCB layers with two-ounce copper; and no less
than one ounce. If the PCB design uses multiple copper layers (recommended), thermal vias can also be
connected to the inner layer heat-spreading ground planes.
8. Keep switch area small. Keep the copper area connecting the SW pin to the inductor as short and wide as
possible. At the same time the total area of this node should be minimized to help reduce radiated EMI.
See the following PCB layout resources for additional important guidelines:
• Layout Guidelines for Switching Power Supplies
• Simple Switcher PCB Layout Guidelines
• Construction Your Power Supply- Layout Considerations
• Low Radiated EMI Layout Made Simple with LM4360x and LM4600x
34
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Copyright © 2018–2019, Texas Instruments Incorporated
Product Folder Links: LMR33620-Q1
LMR33620-Q1
www.ti.com
SNVSB27B – JUNE 2018 – REVISED MARCH 2019
Layout Guidelines (continued)
VIN
CIN
KEEP
CURRENT
LOOP
SMALL
SW
GND
Figure 54. Current Loops with Fast Edges
11.1.1 Ground and Thermal Considerations
As mentioned above, TI recommends using one of the middle layers as a solid ground plane. A ground plane
provides shielding for sensitive circuits and traces. It also provides a quiet reference potential for the control
circuitry. The AGND and PGND pins should be connected to the ground planes using vias next to the bypass
capacitors. PGND pins are connected directly to the source of the low side MOSFET switch, and also connected
directly to the grounds of the input and output capacitors. The PGND net contains noise at the switching
frequency and may bounce due to load variations. The PGND trace, as well as the VIN and SW traces, must be
constrained to one side of the ground planes. The other side of the ground plane contains much less noise and
must be used for sensitive routes.
Use as much copper as possible, for system ground plane, on the top and bottom layers for the best heat
dissipation. Use a four-layer board with the copper thickness for the four layers, starting from the top as: 2 oz / 1
oz / 1 oz / 2 oz. A four-layer board with enough copper thickness, and proper layout, provides low current
conduction impedance, proper shielding and lower thermal resistance.
Submit Documentation Feedback
Copyright © 2018–2019, Texas Instruments Incorporated
Product Folder Links: LMR33620-Q1
35
LMR33620-Q1
SNVSB27B – JUNE 2018 – REVISED MARCH 2019
www.ti.com
11.2 Layout Example
VOUT
VOUT
INDUCTOR
COUT
COUT
COUT
COUT
GND
GND
12
1
CIN
CHF
11
2
10
3
9
EN
4
8
PGOOD
VIN
T
5
6
7
CVCC
RFBT
VIN
CHF
CBOO
CIN
RFBB
GND
HEATSINK
GND
HEATSINK
INNER GND PLANE
Top Trace/Plane
Inner GND Plane
VIN Strap on Inner Layer
Top
Inner GND Plane
VIN Strap and
GND Plane
Signal
traces and
GND Plane
VIA to Signal Layer
VIA to GND Planes
VIA to VIN Strap
Trace on Signal Layer
Figure 55. Example Layout for VQFN Package
36
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Copyright © 2018–2019, Texas Instruments Incorporated
Product Folder Links: LMR33620-Q1
LMR33620-Q1
www.ti.com
SNVSB27B – JUNE 2018 – REVISED MARCH 2019
12 Device and Documentation Support
12.1 Device Support
12.1.1 Development Support
12.1.1.1 Custom Design With WEBENCH® Tools
Click here to create a custom design using the LM33620-Q1 device with the WEBENCH® Power Designer.
1. Start by entering the input voltage (VIN), output voltage (VOUT), and output current (IOUT) requirements.
2. Optimize the design for key parameters such as efficiency, footprint, and cost using the optimizer dial.
3. Compare the generated design with other possible solutions from Texas Instruments.
The WEBENCH Power Designer provides a customized schematic along with a list of materials with real-time
pricing and component availability.
In most cases, these actions are available:
• Run electrical simulations to see important waveforms and circuit performance
• Run thermal simulations to understand board thermal performance
• Export customized schematic and layout into popular CAD formats
• Print PDF reports for the design, and share the design with colleagues
Get more information about WEBENCH tools at www.ti.com/WEBENCH.
12.2 Documentation Support
12.2.1 Related Documentation
For related documentation see the following:
• Thermal Design by Insight not Hindsight
• A Guide to Board Layout for Best Thermal Resistance for Exposed Pad Packages
• Semiconductor and IC Package Thermal Metrics
• Thermal Design Made Simple with LM43603 and LM43602
• SLMA002 PowerPADTM Thermally Enhanced Package
• PowerPADTM Made Easy
• SBVA025 Using New Thermal Metrics
• Layout Guidelines for Switching Power Supplies
• Simple Switcher PCB Layout Guidelines
• Construction Your Power Supply- Layout Considerations
• Low Radiated EMI Layout Made Simple with LM4360x and LM4600x
12.3 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper
right corner, click on Alert me to register and receive a weekly digest of any product information that has
changed. For change details, review the revision history included in any revised document.
12.4 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
Submit Documentation Feedback
Copyright © 2018–2019, Texas Instruments Incorporated
Product Folder Links: LMR33620-Q1
37
LMR33620-Q1
SNVSB27B – JUNE 2018 – REVISED MARCH 2019
www.ti.com
12.5 Trademarks
E2E is a trademark of Texas Instruments.
WEBENCH is a registered trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
12.6 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
12.7 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
13 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
38
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Product Folder Links: LMR33620-Q1
PACKAGE OPTION ADDENDUM
www.ti.com
1-Mar-2019
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
LMR33620AQ5RNXRQ1
ACTIVE
VQFN-HR
RNX
12
3000
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
-40 to 125
620AQ5
LMR33620AQ5RNXTQ1
ACTIVE
VQFN-HR
RNX
12
250
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
-40 to 125
620AQ5
LMR33620AQRNXRQ1
ACTIVE
VQFN-HR
RNX
12
3000
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
-40 to 125
Z620AQ
LMR33620AQRNXTQ1
ACTIVE
VQFN-HR
RNX
12
250
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
-40 to 125
Z620AQ
LMR33620BQRNXRQ1
ACTIVE
VQFN-HR
RNX
12
3000
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
-40 to 125
Z620BQ
LMR33620BQRNXTQ1
ACTIVE
VQFN-HR
RNX
12
250
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
-40 to 125
Z620BQ
LMR33620CQ3RNXRQ1
ACTIVE
VQFN-HR
RNX
12
3000
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
-40 to 125
Z20CQ3
LMR33620CQ3RNXTQ1
ACTIVE
VQFN-HR
RNX
12
250
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
-40 to 125
Z20CQ3
LMR33620CQ5RNXRQ1
ACTIVE
VQFN-HR
RNX
12
3000
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
-40 to 125
Z205CQ
LMR33620CQ5RNXTQ1
ACTIVE
VQFN-HR
RNX
12
250
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
-40 to 125
Z205CQ
LMR33620CQRNXRQ1
ACTIVE
VQFN-HR
RNX
12
3000
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
-40 to 125
Z620CQ
LMR33620CQRNXTQ1
ACTIVE
VQFN-HR
RNX
12
250
Green (RoHS
& no Sb/Br)
CU SN
Level-2-260C-1 YEAR
-40 to 125
Z620CQ
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
1-Mar-2019
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based
flame retardants must also meet the <=1000ppm threshold requirement.
(3)
MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4)
There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5)
Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6)
Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish
value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
OTHER QUALIFIED VERSIONS OF LMR33620-Q1 :
• Catalog: LMR33620
NOTE: Qualified Version Definitions:
• Catalog - TI's standard catalog product
Addendum-Page 2
PACKAGE MATERIALS INFORMATION
www.ti.com
15-Jun-2019
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
B0
(mm)
K0
(mm)
P1
(mm)
W
Pin1
(mm) Quadrant
LMR33620AQ5RNXRQ1
VQFNHR
RNX
12
3000
180.0
8.4
2.3
3.2
1.0
4.0
8.0
Q1
LMR33620AQ5RNXTQ1
VQFNHR
RNX
12
250
180.0
8.4
2.3
3.2
1.0
4.0
8.0
Q1
LMR33620AQRNXRQ1
VQFNHR
RNX
12
3000
180.0
8.4
2.3
3.2
1.0
4.0
8.0
Q1
LMR33620AQRNXTQ1
VQFNHR
RNX
12
250
180.0
8.4
2.3
3.2
1.0
4.0
8.0
Q1
LMR33620BQRNXRQ1
VQFNHR
RNX
12
3000
180.0
8.4
2.3
3.2
1.0
4.0
8.0
Q1
LMR33620BQRNXTQ1
VQFNHR
RNX
12
250
180.0
8.4
2.3
3.2
1.0
4.0
8.0
Q1
LMR33620CQ3RNXRQ1
VQFNHR
RNX
12
3000
180.0
8.4
2.3
3.2
1.0
4.0
8.0
Q1
LMR33620CQ3RNXTQ1
VQFNHR
RNX
12
250
180.0
8.4
2.3
3.2
1.0
4.0
8.0
Q1
LMR33620CQ5RNXRQ1
VQFNHR
RNX
12
3000
180.0
8.4
2.3
3.2
1.0
4.0
8.0
Q1
LMR33620CQ5RNXTQ1
VQFNHR
RNX
12
250
180.0
8.4
2.3
3.2
1.0
4.0
8.0
Q1
LMR33620CQRNXRQ1
VQFN-
RNX
12
3000
180.0
8.4
2.3
3.2
1.0
4.0
8.0
Q1
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
15-Jun-2019
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
B0
(mm)
K0
(mm)
P1
(mm)
3.2
1.0
4.0
W
Pin1
(mm) Quadrant
HR
LMR33620CQRNXTQ1
VQFNHR
RNX
12
250
180.0
8.4
2.3
8.0
Q1
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
LMR33620AQ5RNXRQ1
VQFN-HR
RNX
12
3000
195.0
200.0
45.0
LMR33620AQ5RNXTQ1
VQFN-HR
RNX
12
250
195.0
200.0
45.0
LMR33620AQRNXRQ1
VQFN-HR
RNX
12
3000
195.0
200.0
45.0
LMR33620AQRNXTQ1
VQFN-HR
RNX
12
250
195.0
200.0
45.0
LMR33620BQRNXRQ1
VQFN-HR
RNX
12
3000
195.0
200.0
45.0
LMR33620BQRNXTQ1
VQFN-HR
RNX
12
250
195.0
200.0
45.0
LMR33620CQ3RNXRQ1
VQFN-HR
RNX
12
3000
195.0
200.0
45.0
LMR33620CQ3RNXTQ1
VQFN-HR
RNX
12
250
195.0
200.0
45.0
LMR33620CQ5RNXRQ1
VQFN-HR
RNX
12
3000
195.0
200.0
45.0
LMR33620CQ5RNXTQ1
VQFN-HR
RNX
12
250
195.0
200.0
45.0
LMR33620CQRNXRQ1
VQFN-HR
RNX
12
3000
195.0
200.0
45.0
LMR33620CQRNXTQ1
VQFN-HR
RNX
12
250
195.0
200.0
45.0
Pack Materials-Page 2
GENERIC PACKAGE VIEW
RNX 12
2 x 3 mm, 0.5 mm pitch
VQFN-HR - 1 mm max height
PLASTIC QUAD FLATPACK-NO LEAD
Images above are just a representation of the package family, actual package may vary.
Refer to the product data sheet for package details.
4224286/A
PACKAGE OUTLINE
RNX0012B
VQFN-HR - 0.9 mm max height
SCALE 4.500
PLASTIC QUAD FLATPACK - NO LEAD
2.1
1.9
B
A
PIN 1 INDEX AREA
3.1
2.9
0.1 MIN
(0.05)
SECTION A-A
A-A 40.000
TYPICAL
0.9
0.8
C
SEATING PLANE
0.05
0.00
0.08 C
1
SYMM
(0.2) TYP
7
5
2X
0.675
2X
1.125
4X 0.5
8
4
PKG
1.725
1.525
2X
0.65
A
1
11
A
12
PIN 1 ID
11X
0.3
0.2
11X
0.5
0.3
0.3
0.2
0.1
0.05
C B A
C
4223969/C 10/2018
NOTES:
1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing
per ASME Y14.5M.
2. This drawing is subject to change without notice.
3. The package thermal pad must be soldered to the printed circuit board for thermal and mechanical performance.
www.ti.com
EXAMPLE BOARD LAYOUT
RNX0012B
VQFN-HR - 0.9 mm max height
PLASTIC QUAD FLATPACK - NO LEAD
(0.25)
12
11X (0.6)
1
11
2X (0.65)
11X
(0.25)
(1.825)
2X
(1.125)
(0.788)
PKG
2X
(0.675)
4X (0.5)
8
4
(1.4)
(R0.05) TYP
5
SYMM
7
(1.8)
LAND PATTERN EXAMPLE
EXPOSED METAL SHOWN
SCALE:25X
0.07 MAX
ALL AROUND
0.07 MIN
ALL AROUND
SOLDER MASK
OPENING
METAL EDGE
EXPOSED
METAL
SOLDER MASK
OPENING
EXPOSED
METAL
NON SOLDER MASK
DEFINED
(PREFERRED)
METAL
SOLDER MASK
DEFINED
PADS 1, 2, 10-12
SOLDER MASK DETAILS
4223969/C 10/2018
NOTES: (continued)
4. This package is designed to be soldered to a thermal pad on the board. For more information, see Texas Instruments literature
number SLUA271 (www.ti.com/lit/slua271).
www.ti.com
EXAMPLE STENCIL DESIGN
RNX0012B
VQFN-HR - 0.9 mm max height
PLASTIC QUAD FLATPACK - NO LEAD
2X (0.25)
2X (0.812)
12
11X (0.6)
11X (0.25)
1
11
2X
(0.65)
EXPOSED METAL
(1.294)
2X
(1.125)
PKG
(0.282)
2X (0.675)
4X (0.5)
8
4
(1.4)
(R0.05) TYP
5
SYMM
7
(1.8)
SOLDER PASTE EXAMPLE
BASED ON 0.125 mm THICK STENCIL
FOR PAD 12
87.7% PRINTED SOLDER COVERAGE BY AREA
SCALE:25X
4223969/C 10/2018
NOTES: (continued)
5. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate
design recommendations.
www.ti.com
IMPORTANT NOTICE AND DISCLAIMER
TI PROVIDES TECHNICAL AND RELIABILITY DATA (INCLUDING DATASHEETS), DESIGN RESOURCES (INCLUDING REFERENCE
DESIGNS), APPLICATION OR OTHER DESIGN ADVICE, WEB TOOLS, SAFETY INFORMATION, AND OTHER RESOURCES “AS IS”
AND WITH ALL FAULTS, AND DISCLAIMS ALL WARRANTIES, EXPRESS AND IMPLIED, INCLUDING WITHOUT LIMITATION ANY
IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRD
PARTY INTELLECTUAL PROPERTY RIGHTS.
These resources are intended for skilled developers designing with TI products. You are solely responsible for (1) selecting the appropriate
TI products for your application, (2) designing, validating and testing your application, and (3) ensuring your application meets applicable
standards, and any other safety, security, or other requirements. These resources are subject to change without notice. TI grants you
permission to use these resources only for development of an application that uses the TI products described in the resource. Other
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Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2019, Texas Instruments Incorporated
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