Texas Instruments | LMZ31707 7-A Power module with 2.95-V to 17-V input and current sharing (Rev. D) | Datasheet | Texas Instruments LMZ31707 7-A Power module with 2.95-V to 17-V input and current sharing (Rev. D) Datasheet

Texas Instruments LMZ31707 7-A Power module with 2.95-V to 17-V input and current sharing (Rev. D) Datasheet
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LMZ31707
SLVSBV7D – JUNE 2013 – REVISED MARCH 2019
LMZ31707 7-A Power module with 2.95-V to 17-V input and
current sharing in QFN package
1 Features
3 Description
•
The LMZ31707 SIMPLE SWITCHER® power module
is an easy-to-use integrated power solution that
combines a 7-A DC-DC converter with power
MOSFETs, a shielded inductor, and passives into a
low profile, QFN package. This total power solution
allows as few as three external components and
eliminates the loop compensation and magnetics part
selection process.
1
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Complete integrated power solution allows
small footprint, low-profile design
10 mm × 10 mm × 4.3 mm package
– Pin compatible with LMZ31710 and LMZ31704
Efficiencies Up To 95%
Eco-mode™ / light load efficiency (LLE)
Wide-output voltage adjust
0.6 V to 5.5 V, with 1% reference accuracy
Supports parallel operation for higher current
Optional split power rail allows
input voltage down to 2.95 V
Adjustable switching frequency
(200 kHz to 1.2 MHz)
Synchronizes to an external clock
Provides 180° out-of-phase clock signal
Adjustable slow start
Output voltage sequencing / tracking
Power good output
Programmable undervoltage lockout (UVLO)
Overcurrent and overtemperature protection
Pre-Bias output start-up
Operating temperature range: –40°C to +85°C
Enhanced thermal performance: 13.3°C/W
Meets EN55022 Class B emissions
– Integrated shielded inductor
Create a custom design using the LMZ31707 with
the WEBENCH® Power Designer
2 Applications
•
•
•
•
Broadband and communications infrastructure
Automated test and medical equipment
Compact PCI / PCI express / PXI express
DSP and FPGA point-of-load applications
The 10 × 10 × 4.3 mm QFN package is easy to
solder onto a printed circuit board and allows a
compact point-of-load design. Achieves greater than
95% efficiency and excellent power dissipation
capability with a thermal impedance of 13.3°C/W. The
LMZ31707 offers the flexibility and the feature-set of
a discrete point-of-load design and is ideal for
powering a wide range of ICs and systems.
Advanced packaging technology affords a robust and
reliable power solution compatible with standard QFN
mounting and testing techniques.
Simplified Application
VIN
CIN
PVIN
VIN
ISHARE
VOUT
VOUT
SENSE+
COUT
LMZ31707
SYNC_OUT
PWRGD
INH/UVLO
VADJ
SS/TR
RT/CLK
STSEL
AGND PGND
RSET
RRT
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.
LMZ31707
SLVSBV7D – JUNE 2013 – REVISED MARCH 2019
www.ti.com
4 Specifications
4.1 Absolute Maximum Ratings (1)
over operating temperature range (unless otherwise noted)
Input Voltage
Output Voltage
MIN
MAX
UNIT
VIN, PVIN
–0.3
20
V
INH/UVLO, PWRGD, RT/CLK, SENSE+
–0.3
6
V
ILIM, VADJ, SS/TR, STSEL, SYNC_OUT, ISHARE,
OCP_SEL
–0.3
3
V
PH
–1
20
V
PH 10ns Transient
–3
20
V
–0.3
6
V
VOUT
RT/CLK, INH/UVLO
Source Current
Sink Current
±100
µA
PH
current limit
A
PH
current limit
A
PVIN
current limit
A
–0.1
2
mA
Operating Junction Temperature
PWRGD
–40
125 (2)
°C
Storage Temperature
–65
150
°C
Peak Reflow Case Temperature
(3)
245
Maximum Number of Reflows Allowed (3)
°C
3 (4)
Mechanical Shock
Mil-STD-883D, Method 2002.3, 1 msec, 1/2 sine, mounted
Mechanical Vibration
Mil-STD-883D, Method 2007.2, 20-2000Hz
(1)
(4)
1500
G
20
Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating
conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
See the temperature derating curves in the Typical Characteristics section for thermal information.
For soldering specifications, refer to the Soldering Requirements for BQFN Packages application note.
Devices with a date code prior to week 14 2018 (1814) have a peak reflow case temperature of 240°C with a maximum of one reflow.
(2)
(3)
(4)
4.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic
discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
±1500
Charged-device model (CDM), per JEDEC specification JESD22-C101 (2)
±1000
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
4.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
NOM
MAX
PVIN
Input Switching Voltage
VIN
Input Bias Voltage
VOUT
Output Voltage
0.6
5.5
fSW
Switching Frequency
200
1200
UNIT
2.95
17
V
4.5
17
V
V
kHz
4.4 Package Specifications
LMZ31707
UNIT
Weight
Flammability
MTBF Calculated reliability
2
1.45 grams
Meets UL 94 V-O
Per Bellcore TR-332, 50% stress, TA = 40°C, ground benign
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37.4 MHrs
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SLVSBV7D – JUNE 2013 – REVISED MARCH 2019
4.5 Thermal Information
LMZ31707
THERMAL METRIC (1)
RVQ42
UNIT
42 PINS
Junction-to-ambient thermal resistance (2)
θJA
ψJT
Junction-to-top characterization parameter
ψJB
Junction-to-board characterization parameter (4)
(1)
(2)
(3)
(4)
13.3
°C/W
1.6
°C/W
5.3
°C/W
(3)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
The junction-to-ambient thermal resistance, θJA, applies to devices soldered directly to a 100 mm × 100 mm double-sided PCB with
2 oz. copper and natural convection cooling. Additional airflow reduces θJA.
The junction-to-top characterization parameter, ψJT, estimates the junction temperature, TJ, of a device in a real system, using a
procedure described in JESD51-2A (sections 6 and 7). TJ = ψJT * Pdis + TT; where Pdis is the power dissipated in the device and TT is
the temperature of the top of the device.
The junction-to-board characterization parameter, ψJB, estimates the junction temperature, TJ, of a device in a real system, using a
procedure described in JESD51-2A (sections 6 and 7). TJ = ψJB * Pdis + TB; where Pdis is the power dissipated in the device and TB is
the temperature of the board 1mm from the device.
4.6 Electrical Characteristics
Over –40°C to 85°C free-air temperature, PVIN = VIN = 12 V, VOUT = 1.8 V, IOUT = 7 A,
CIN = 0.1 µF + 2 x 22 µF ceramic + 100 µF bulk, COUT = 4 x 47 µF ceramic (unless otherwise noted)
PARAMETER
TEST CONDITIONS
IOUT
Output current
TA = 85°C, natural convection
VIN
Input bias voltage range
PVIN
Input switching voltage range
UVLO
VIN Undervoltage lockout
VOUT(adj)
VOUT
A
4.5
17
V
Over output current range
2.95 (2)
17 (3)
V
VIN Increasing
Output voltage adjust range
Over output current range
0.6
Set-point voltage tolerance
TA = 25°C, IOUT = 0 A
Temperature variation
–40°C ≤ TA ≤ +85°C, IOUT = 0 A
±0.2%
Line regulation
Over input voltage range
±0.1%
Load regulation
Over output current range
±0.2%
Total output voltage variation
Includes set-point, line, load, and temperature variation
Efficiency
Transient response
(1)
(2)
(3)
(4)
4.0
3.5
Current limit threshold
UNIT
Over output current range
VIN Decreasing
Output voltage ripple
MAX
7
PVIN = VIN = 5 V
IO = 4 A
ILIM
TYP
0
PVIN = VIN = 12 V
IO = 4 A
η
MIN
(1)
4.5
3.85
5.5
V
V
±1% (4)
±1.5% (4)
VOUT = 5.0 V, fSW = 1 MHz
94 %
VOUT = 3.3 V, fSW = 750 kHz
92 %
VOUT = 2.5 V, fSW = 750 kHz
90 %
VOUT = 1.8 V, fSW = 500 kHz
89 %
VOUT = 1.2 V, fSW = 300 kHz
87 %
VOUT = 0.9 V, fSW = 250 kHz
85 %
VOUT = 0.6 V, fSW = 200 kHz
82 %
VOUT = 3.3 V, fSW = 750 kHz
95 %
VOUT = 2.5 V, fSW = 750 kHz
93 %
VOUT = 1.8 V, fSW = 500 kHz
92 %
VOUT = 1.2 V, fSW = 300 kHz
90 %
VOUT = 0.9 V, fSW = 250 kHz
87 %
VOUT = 0.6 V, fSW = 200 kHz
84 %
20 MHz bandwith
14
mVP-P
ILIM pin open
12
A
ILIM pin to AGND
1.0 A/µs load step from
25 to 75% IOUT(max)
9
A
Recovery time
tbd
µs
VOUT over/undershoot
tbd
mV
See the Light Load Efficiency (LLE) section for more information for output voltages < 1.5 V.
The minimum PVIN is 2.95 V or (VOUT + 0.7 V), whichever is greater. See Table 7 for more details.
The maximum PVIN voltage is 17 V or (22 x VOUT), whichever is less. See Table 7 for more details.
The stated limit of the set-point voltage tolerance includes the tolerance of both the internal voltage reference and the internal
adjustment resistor. The overall output voltage tolerance will be affected by the tolerance of the external RSET resistor.
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Electrical Characteristics (continued)
Over –40°C to 85°C free-air temperature, PVIN = VIN = 12 V, VOUT = 1.8 V, IOUT = 7 A,
CIN = 0.1 µF + 2 x 22 µF ceramic + 100 µF bulk, COUT = 4 x 47 µF ceramic (unless otherwise noted) (1)
PARAMETER
VINH
Inhibit threshold voltage
IINH
II(stby)
TEST CONDITIONS
Inhibit Low Voltage
-0.3
1.1
INH Input current
VINH < 1.1 V
-1.15
INH Hysteresis current
VINH > 1.3 V
-3.3
Input standby current
INH pin to AGND
PWRGD Thresholds
VOUT falling
PWRGD Low Voltage
I(PWRGD) = 0.5 mA
Switching frequency
RRT = 169 kΩ
fCLK
Synchronization frequency
VCLK-H
CLK High-Level
VCLK-L
CLK Low-Level
DCLK
CLK Duty Cycle
Thermal Shutdown
2
Good
95%
Fault
108%
Fault
91%
Good
104%
CLK Control
Equivalent series resistance (ESR)
(5)
(6)
(7)
(8)
4
µA
200
1200
kHz
2.0
5.5
500
50
V
80
%
175
°C
10
°C
µF
100 (6)
47 (7)
V
0.5
44 (6)
Non-ceramic
Non-ceramic
μA
10
V
Thermal shutdown hysteresis
External output capacitance
μA
kHz
Thermal shutdown
Ceramic
V
0.3
20
Ceramic
UNIT
600
400
External input capacitance
COUT
MAX
open (5)
fSW
CIN
TYP
1.3
VOUT rising
Power Good
MIN
Inhibit High Voltage
200
1500
220 (7)
5000 (8)
35
µF
mΩ
This pin has an internal pull-up. If it is left open, the device operates when input power is applied. A small, low-leakage MOSFET is
recommended for control. When the device is operating and no UVLO resistor divider is present on this pin, the open voltage is typically
2.9 V.
A minimum of 44 µF of external ceramic capacitance is required across the input (VIN and PVIN connected) for proper operation. An
additional 100 µF of bulk capacitance is recommended. It is also recommended to place a 0.1 µF ceramic capacitor directly across the
PVIN and PGND pins of the device. Locate the input capacitance close to the device. When operating with split VIN and PVIN rails,
place 4.7µF of ceramic capacitance directly at the VIN pin. See Table 4 for more details.
The amount of required output capacitance varies depending on the output voltage (see Table 3 ). The amount of required capacitance
must include at least 1x 47µF ceramic capacitor. Locate the capacitance close to the device. Adding additional capacitance close to the
load improves the response of the regulator to load transients. See Table 3 and Table 4 more details.
When using both ceramic and non-ceramic output capacitors, the combined maximum must not exceed 5000 µF. It may be necessary to
increase the slow start time when turning on into the maximum capacitance. See theSlow Start (SS/TR) section for information on
adjusting the slow start time.
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5 Device Information
Functional Block Diagram
OCP_SEL
ILIM
OCP
INH/UVLO
Shutdown
Logic
PWRGD
VIN
Thermal
Shutdown
SENSE+
VIN
UVLO
PWRGD
Logic
PVIN
+
+
PH
VADJ
SS/TR
VREF
Comp
STSEL
Current
Share
ISHARE
SYNC_OUT
RT/CLK
Power
Stage
and
Control
Logic
VOUT
Oscillator
with PLL
PGND
AGND
LMZ31707
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Pin Functions
TERMINAL
NAME
DESCRIPTION
NO.
2
AGND
23
Zero volt reference for the analog control circuit. These pins are not connected together internal to the
device and must be connected to one another using an AGND plane of the PCB. These pins are associated
with the internal analog ground (AGND) of the device. Keep AGND seperate from PGND, as a single
connection is made internal to the device. See Layout Recommendations.
20
21
PGND
31
32
This is the return current path for the power stage of the device. Connect these pins to the load and to the
bypass capacitors associated with PVIN and VOUT. Keep PGND seperate from AGND, as a single
connection is made internal to the device.
33
VIN
3
Input bias voltage pin. Supplies the control circuitry of the power converter. Connect this pin to the input bias
supply. Connect bypass capacitors between this pin and PGND.
1
11
PVIN
12
Input switching voltage. Supplies voltage to the power switches of the converter. Connect these pins to the
input supply. Connect bypass capacitors between these pins and PGND.
39
40
34
35
36
VOUT
37
Output voltage. These pins are connected to the internal output inductor. Connect these pins to the output
load and connect external bypass capacitors between these pins and PGND.
38
41
10
13
14
15
PH
16
17
Phase switch node. These pins must be connected to one another using a small copper island under the
device for thermal relief. Do not place any external component on these pins or tie them to a pin of another
function.
18
19
42
5
DNC
9
Do Not Connect. Do not connect these pins to AGND, to another DNC pin, or to any other voltage. These
pins are connected to internal circuitry. Each pin must be soldered to an isolated pad.
24
ISHARE
25
Current share pin. Connect this pin to other LMZ31707 device's ISHARE pin when paralleling multple
LMZ31707 devices. When unused, treat this pin as a Do Not Connect (DNC) and leave it isolated from all
other signals or ground.
OCP_SEL
4
Over current protection select pin. Leave this pin open for hiccup mode operation. Connect this pin to AGND
for cycle-by-cycle operation. See Overcurrent Protection for more details.
ILIM
6
Current limit pin. Leave this pin open for full current limit threshold. Connect this pin to AGND to reduce the
current limit threshold by appoximately 3 A.
SYNC_OUT
7
Synchronization output pin. Provides a 180° out-of-phase clock signal.
PWRGD
8
Power Good flag pin. This open drain output asserts low if the output voltage is more than approximately
±6% out of regulation. A pull-up resistor is required.
RT/CLK
22
This pin is connected to an internal frequency setting resistor which sets the default switching frequency. An
external resistor can be connected from this pin to AGND to increase the frequency. This pin can also be
used to synchronize to an external clock.
VADJ
26
Connecting a resistor between this pin and AGND sets the output voltage.
SENSE+
27
Remote sense connection. This pin must be connected to VOUT at the load or at the device pins. Connect
this pin to VOUT at the load for improved regulation.
6
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Pin Functions (continued)
TERMINAL
DESCRIPTION
NAME
NO.
SS/TR
28
Slow-start and tracking pin. Connecting an external capacitor to this pin adjusts the output voltage rise time.
A voltage applied to this pin allows for tracking and sequencing control.
STSEL
29
Slow-start or track feature select. Connect this pin to AGND to enable the internal SS capacitor. Leave this
pin open to enable the TR feature.
INH/UVLO
30
Inhibit and UVLO adjust pin. Use an open drain or open collector logic device to ground this pin to control
the INH function. A resistor divider between this pin, AGND, and PVIN/VIN sets the UVLO voltage.
PVIN
1
AGND
2
VIN
40 39
PGND
PGND
VOUT
VOUT
VOUT
VOUT
VOUT
PVIN
PVIN
RVQ PACKAGE
(TOP VIEW)
38 37 36 35 34 33 32
31
PGND
30
INH/UVLO
3
29
STSEL
OCP_SEL
4
28
SS/TR
DNC
5
27
SENSE+
ILIM
6
26
VADJ
SYNC_OUT
7
25
ISHARE
PWRGD
8
24
DNC
DNC
9
23
AGND
22
RT/CLK
21
PGND
PGND
PH
PH
PH
14 15 16 17 18 19 20
PH
12 13
PH
11
PH
PH
PVIN
42
PH
10
PVIN
PH
41 VOUT
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6 Typical Characteristics (PVIN = VIN = 12 V)
The electrical characteristic data has been developed from actual products tested at 25°C. This data is considered typical for
the converter. Applies to Figure 1, Figure 2, and Figure 3. The temperature derating curves represent the conditions at which
internal components are at or below the manufacturer's maximum operating temperatures. Derating limits apply to devices
soldered directly to a 100 mm × 100 mm, 4-layer PCB with 2 oz. copper. Applies to Figure 4.
30
100
Output Ripple Voltage (mV)
90
70
Vo = 5.0V, fsw = 1MHz
Vo = 3.3V, fsw = 750kHz
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
Vo = 1.2V, fsw = 300kHz
Vo = 0.9V, fsw = 250kHz
60
50
40
0
1
2
3
4
5
6
Output Current (A)
25
20
15
10
5
0
7
2.5
1.5
1.0
50
20
4
5
6
Output Current (A)
7
Airflow = 0 LFM
40
0.0
3
All Output Voltages
0
Gain (dB)
1
2
3
4
5
Output Current (A)
C004
Figure 3. Power Dissipation vs. Output Current
6
7
C001
Figure 4. Safe Operating Area
40
120
30
90
20
60
10
30
0
0
-30
±10
-60
±20
±30
7
C004
60
30
2
6
70
0.5
1
5
80
2.0
0
4
Figure 2. Voltage Ripple vs. Output Current
Ambient Temperature (ƒC)
Power Dissipation (W)
3.0
3
90
Vo = 5.0V, fsw = 1MHz
Vo = 3.3V, fsw = 750kHz
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
Vo = 1.2V, fsw = 300kHz
Vo = 0.9V, fsw = 250kHz
3.5
2
Output Current (A)
Figure 1. Efficiency vs. Output Current
4.0
1
C001
Phase (°)
Efficiency (%)
80
Vo = 5.0V, fsw = 1MHz
Vo = 3.3V, fsw = 750kHz
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
Vo = 1.2V, fsw = 300kHz
Vo = 0.9V, fsw = 250kHz
Gain
-90
Phase
±40
1000
-120
10k
100k
Frequency (kHz)
C001
Figure 5. VOUT= 1.8 V, IOUT= 7 A, COUT= 200 µF ceramic, fSW= 500 kHz
8
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7 Typical Characteristics (PVIN = VIN = 5 V)
The electrical characteristic data has been developed from actual products tested at 25°C. This data is considered typical for
the converter. Applies to Figure 6, Figure 7, and Figure 8. The temperature derating curves represent the conditions at which
internal components are at or below the manufacturer's maximum operating temperatures. Derating limits apply to devices
soldered directly to a 100 mm × 100 mm, 4-layer PCB with 2 oz. copper. Applies to Figure 9.
100
30
Output Voltage Ripple (mV)
80
70
Vo = 3.3V, fsw = 750kHz
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
Vo = 1.2V, fsw = 300kHz
Vo = 0.9V, fsw = 250kHz
Vo = 0.6V, fsw = 200kHz
60
50
40
0
1
2
3
4
5
6
Output Current (A)
25
20
15
10
5
7
0
4
5
6
7
C004
Figure 7. Voltage Ripple vs. Output Current
80
Ambient Temperature (ƒC)
Power Dissipation (W)
2.0
3
90
Vo = 3.3V, fsw = 750kHz
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
Vo = 1.2V, fsw = 300kHz
Vo = 0.9V, fsw = 250kHz
Vo = 0.6V, fsw = 200kHz
2.5
2
Output Current (A)
Figure 6. Efficiency vs. Output Current
3.0
1
C001
1.5
1.0
0.5
70
60
50
Airflow = 0 LFM
40
30
0.0
All Output Voltages
20
0
1
2
3
4
5
6
Output Current (A)
7
0
2
4
5
6
7
C001
Figure 9. Safe Operating Area
40
120
30
90
20
60
10
30
0
0
-30
±10
-60
±20
±30
3
Output Current (A)
Figure 8. Power Dissipation vs. Output Current
Gain (dB)
1
C004
Phase (°)
Efficiency (%)
90
Vo = 3.3V, fsw = 750kHz
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
Vo = 1.2V, fsw = 300kHz
Vo = 0.9V, fsw = 250kHz
Vo = 0.6V, fsw = 200kHz
Gain
-90
Phase
±40
1000
-120
10k
100k
Frequency (kHz)
C001
Figure 10. VOUT= 1.8 V, IOUT= 7 A, COUT= 200 µF ceramic, fSW= 500 kHz
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8 Typical Characteristics (PVIN = 3.3 V, VIN = 5 V)
The electrical characteristic data has been developed from actual products tested at 25°C. This data is considered typical for
the converter. Applies to Figure 11, Figure 12, and Figure 13. The temperature derating curves represent the conditions at
which internal components are at or below the manufacturer's maximum operating temperatures. Derating limits apply to
devices soldered directly to a 100 mm × 100 mm, 4-layer PCB with 2 oz. copper. Applies to Figure 14.
100
30
Output Ripple Voltage (mV)
90
70
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
60
Vo = 1.2V, fsw = 300kHz
50
Vo = 0.9V, fsw = 250kHz
Vo = 0.6V, fsw = 200kHz
40
0
1
2
3
4
5
6
25
20
15
10
5
7
Output Current (A)
0
4
5
6
7
C004
Figure 12. Voltage Ripple vs. Output Current
80
Ambient Temperature (ƒC)
Power Dissipation (W)
2.0
3
90
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
Vo = 1.2V, fsw = 300kHz
Vo = 0.9V, fsw = 250kHz
Vo = 0.6V, fsw = 200kHz
2.5
2
Output Current (A)
Figure 11. Efficiency vs. Output Current
3.0
1
C001
1.5
1.0
0.5
70
60
50
Airflow = 0 LFM
40
30
0.0
All Output Voltages
20
0
1
2
3
4
5
6
7
Output Current (A)
0
2
4
5
6
7
C001
Figure 14. Safe Operating Area
40
120
30
90
20
60
10
30
0
0
-30
±10
-60
±20
±30
3
Output Current (A)
Figure 13. Power Dissipation vs. Output Current
Gain (dB)
1
C004
Phase (°)
Efficiency (%)
80
Vo = 2.5V, fsw = 750kHz
Vo = 1.8V, fsw = 500kHz
Vo = 1.2V, fsw = 300kHz
Vo = 0.9V, fsw = 250kHz
Vo = 0.6V, fsw = 200kHz
Gain
-90
Phase
±40
1000
-120
10k
100k
Frequency (kHz)
C001
Figure 15. VOUT= 1.8 V, IOUT= 7 A, COUT= 200 µF ceramic, fSW= 500 kHz
10
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9 Application Information
9.1 Adjusting the Output Voltage
The VADJ control sets the output voltage of the LMZ31707. The output voltage adjustment range is from 0.6V to
5.5V. The adjustment method requires the addition of RSET, which sets the output voltage, the connection of
SENSE+ to VOUT, and in some cases RRT which sets the switching frequency. The RSET resistor must be
connected directly between the VADJ (pin 26) and AGND (pin 23). The SENSE+ pin (pin 27) must be connected
to VOUT either at the load for improved regulation or at VOUT of the device. The RRT resistor must be connected
directly between the RT/CLK (pin 22) and AGND (pin 23). Table 1 gives the standard external RSET resistor for a
number of common bus voltages, along with the recommended RRT resistor for that output voltage.
Table 1. Standard RSET Resistor Values for Common Output Voltages
RESISTORS
OUTPUT VOLTAGE VOUT (V)
0.9
1.0
1.2
1.8
2.5
3.3
5.0
RSET (kΩ)
2.87
2.15
1.43
0.715
0.453
0.316
0.196
RRT (kΩ)
1000
1000
487
169
90.9
90.9
63.4
For other output voltages, the value of the required resistor can either be calculated using the following formula,
or simply selected from the range of values given in Table 2.
1.43
RSET =
(kW )
æ æ VOUT ö ö
çç
÷ - 1÷
è è 0.6 ø ø
(1)
Table 2. Standard RSET Resistor Values
VOUT (V)
RSET (kΩ)
RRT(kΩ)
fSW(kHz)
VOUT (V)
RSET (kΩ)
RRT(kΩ)
fSW(kHz)
0.6
open
OPEN
200
3.1
0.348
90.9
750
0.7
8.66
OPEN
200
3.2
0.332
90.9
750
0.8
4.32
OPEN
200
3.3
0.316
90.9
750
0.9
2.87
1000
250
3.4
0.309
90.9
750
1.0
2.15
1000
250
3.5
0.294
90.9
750
1.1
1.74
1000
250
3.6
0.287
90.9
750
1.2
1.43
487
300
3.7
0.280
90.9
750
1.3
1.24
487
300
3.8
0.267
90.9
750
1.4
1.07
487
300
3.9
0.261
90.9
750
1.5
0.953
487
300
4.0
0.255
90.9
750
1.6
0.866
487
300
4.1
0.243
63.4
1000
1.7
0.787
487
300
4.2
0.237
63.4
1000
1.8
0.715
169
500
4.3
0.232
63.4
1000
1.9
0.665
169
500
4.4
0.226
63.4
1000
2.0
0.619
169
500
4.5
0.221
63.4
1000
2.1
0.576
169
500
4.6
0.215
63.4
1000
2.2
0.536
169
500
4.7
0.210
63.4
1000
2.3
0.511
169
500
4.8
0.205
63.4
1000
2.4
0.475
169
500
4.9
0.200
63.4
1000
2.5
0.453
90.9
750
5.0
0.196
63.4
1000
2.6
0.432
90.9
750
5.1
0.191
63.4
1000
2.7
0.412
90.9
750
5.2
0.187
63.4
1000
2.8
0.392
90.9
750
5.3
0.182
63.4
1000
2.9
0.374
90.9
750
5.4
0.178
63.4
1000
3.0
0.357
90.9
750
5.5
0.174
63.4
1000
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9.2 Capacitor Recommendations for the LMZ31707 Power Supply
9.2.1 Capacitor Technologies
9.2.1.1 Electrolytic, Polymer-Electrolytic Capacitors
When using electrolytic capacitors, high-quality, computer-grade electrolytic capacitors are recommended.
Polymer-electrolytic type capacitors are recommended for applications where the ambient operating temperature
is less than 0°C. The Sanyo OS-CON capacitor series is suggested due to the lower ESR, higher rated surge,
power dissipation, ripple current capability, and small package size. Aluminum electrolytic capacitors provide
adequate decoupling over the frequency range of 2 kHz to 150 kHz, and are suitable when ambient temperatures
are above 0°C.
9.2.1.2 Ceramic Capacitors
The performance of aluminum electrolytic capacitors is less effective than ceramic capacitors above 150 kHz.
Multilayer ceramic capacitors have a low ESR and a resonant frequency higher than the bandwidth of the
regulator. They can be used to reduce the reflected ripple current at the input as well as improve the transient
response of the output.
9.2.1.3 Tantalum, Polymer-Tantalum Capacitors
Polymer-tantalum type capacitors are recommended for applications where the ambient operating temperature is
less than 0°C. The Sanyo POSCAP series and Kemet T530 capacitor series are recommended rather than many
other tantalum types due to their lower ESR, higher rated surge, power dissipation, ripple current capability, and
small package size. Tantalum capacitors that have no stated ESR or surge current rating are not recommended
for power applications.
9.2.2 Input Capacitor
The LMZ31707 requires a minimum input capacitance of 44 μF of ceramic type. An additional 100 µF of nonceramic capacitance is recommended for applications with transient load requirements. The voltage rating of
input capacitors must be greater than the maximum input voltage. At worst case, when operating at 50% duty
cycle and maximum load, the combined ripple current rating of the input capacitors must be at least 3.5 Arms.
Table 4 includes a preferred list of capacitors by vendor. It is also recommended to place a 0.1 µF ceramic
capacitor directly across the PVIN and PGND pins of the device. When operating with split VIN and PVIN rails,
place 4.7µF of ceramic capacitance directly at the VIN pin.
9.2.3 Output Capacitor
The required output capacitance is determined by the output voltage of the LMZ31707. See Table 3 for the
amount of required capacitance. The effects of temperature and capacitor voltage rating must be considered
when selecting capacitors to meet the minimum required capacitance. The required output capacitance can be
comprised of all ceramic capacitors, or a combination of ceramic and bulk capacitors. The required capacitance
must include at least one 47 µF ceramic. When adding additional non-ceramic bulk capacitors, low-ESR devices
like the ones recommended in Table 4 are required. The required capacitance above the minimum is determined
by actual transient deviation requirements. Table 4 includes a preferred list of capacitors by vendor.
Table 3. Required Output Capacitance
VOUT RANGE (V)
(1)
12
MINIMUM REQUIRED COUT (µF)
MIN
MAX
0.6
< 0.8
500 µF
(1)
0.8
< 1.2
300 µF
(1)
1.2
< 3.0
200 µF
(1)
3.0
< 4.0
100 µF
(1)
4.0
5.5
47 µF ceramic
Minimum required must include at least one 47 µF ceramic capacitor.
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Table 4. Recommended Input/Output Capacitors (1)
CAPACITOR CHARACTERISTICS
VENDOR
SERIES
PART NUMBER
WORKING
VOLTAGE
(V)
CAPACITANCE
(µF)
ESR (2)
(mΩ)
Murata
X5R
GRM32ER61E226K
25
22
2
TDK
X5R
C3225X5R0J107M
6.3
100
2
TDK
X5R
C3225X5R0J476K
6.3
47
2
Murata
X5R
GRM32ER60J107M
6.3
100
2
Murata
X5R
GRM32ER60J476M
6.3
47
2
100
30
Panasonic
EEH-ZA
EEH-ZA1E101XP
25
Sanyo
POSCAP
16TQC68M
16
68
50
Kemet
T520
T520V107M010ASE025
10
100
25
Sanyo
POSCAP
10TPE220ML
10
220
25
Sanyo
POSCAP
6TPE100MI
6.3
100
25
Sanyo
POSCAP
2R5TPE220M7
2.5
220
7
Kemet
T530
T530D227M006ATE006
6.3
220
6
Kemet
T530
T530D337M006ATE010
6.3
330
10
Sanyo
POSCAP
2TPF330M6
2.0
330
6
Sanyo
POSCAP
6TPE330MFL
6.3
330
15
(1)
(2)
Capacitor Supplier Verification, RoHS, Lead-free and Material Details
Consult capacitor suppliers regarding availability, material composition, RoHS and lead-free status, and manufacturing process
requirements for any capacitors identified in this table.
Maximum ESR @ 100kHz, 25°C.
9.3 Transient Response
Table 5. Output Voltage Transient Response
CIN1 = 3x 22 µF CERAMIC, CIN2 = 100 µF POLYMER-TANTALUM
VOLTAGE DEVIATION (mV)
VOUT (V)
0.6
COUT1 Ceramic
COUT2 BULK
2 A LOAD STEP,
(1 A/µs)
3.5 A LOAD STEP,
(1 A/µs)
5
500 µF
220 µF
30
45
90
12
500 µF
220 µF
30
45
90
300 µF
220 µF
40
65
95
300 µF
470 µF
35
60
95
300 µF
220 µF
35
60
95
300 µF
470 µF
30
55
95
200 µF
220 µF
50
85
100
200 µF
470 µF
45
75
100
200 µF
220 µF
45
80
100
200 µF
470 µF
40
70
100
200 µF
220 µF
70
105
110
200 µF
470 µF
65
90
110
200 µF
220 µF
65
100
120
200 µF
470 µF
60
90
120
5
100 µF
220 µF
105
177
130
12
100 µF
220 µF
115
190
150
5
0.9
12
5
1.2
12
5
1.8
12
3.3
RECOVERY TIME
(µs)
VIN (V)
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9.4 Transient Waveforms
14
Figure 16. PVIN = 12V, VOUT = 1.2V, 3.5A Load Step
Figure 17. PVIN = 12V, VOUT = 1.8V, 3.5A Load Step
Figure 18. PVIN = 5V, VOUT = 0.9V, 2.5A Load Step
Figure 19. PVIN = 5V, VOUT = 1.8V, 3.5A Load Step
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9.5 Application Schematics
LMZ31707
VIN
VIN / PVIN
4.5 V to 17 V
VOUT
1.2 V
SENSE+
PVIN
VOUT
+
+
CIN1
CIN2
100 µF 47 µF
CIN3
0.1 µF
ISHARE
SYNC_OUT
COUT1
2x 100 µF
COUT2
220 µF
PWRGD
INH/UVLO
RT/CLK
SS/TR
RRT
487 k
VADJ
STSEL AGND PGND
RSET
1.43 k
Figure 20. Typical Schematic
PVIN = VIN = 4.5 V to 17 V, VOUT = 1.2 V
LMZ31707
VIN
VIN / PVIN
4.5 V to 17 V
PVIN
VOUT
3.3 V
SENSE+
VOUT
+
+
CIN1
CIN2
100 µF 47 µF
CIN3
0.1 µF
COUT1
100 µF
ISHARE
SYNC_OUT
COUT2
220 µF
PWRGD
INH/UVLO
RT/CLK
SS/TR
VADJ
STSEL AGND PGND
RSET
316
RRT
90.9 k
Figure 21. Typical Schematic
PVIN = VIN = 4.5 V to 17 V, VOUT = 3.3 V
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Application Schematics (continued)
VIN
4.5 V to 17 V
CIN3
4.7 µF
VIN LMZ31707
VOUT
1.0 V
SENSE+
PVIN
3.3 V
PVIN
VOUT
+
+
CIN1
CIN2
100 µF 47 µF
CIN3
0.1 µF
COUT1
3x 100 µF
ISHARE
SYNC_OUT
COUT2
220 µF
PWRGD
INH/UVLO
RT/CLK
SS/TR
VADJ
STSEL AGND PGND
RSET
2.15 k
RRT
1M
Figure 22. Typical Schematic
PVIN = 3.3 V, VIN = 4.5 V to 17 V, VOUT = 1.0 V
9.6 Custom Design With WEBENCH® Tools
Click here to create a custom design using the LMZ31707 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.
9.7 VIN and PVIN Input Voltage
The LMZ31707 allows for a variety of applications by using the VIN and PVIN pins together or separately. The
VIN voltage supplies the internal control circuits of the device. The PVIN voltage provides the input voltage to the
power converter system.
If tied together, the input voltage for the VIN pin and the PVIN pin can range from 4.5 V to 17 V. If using the VIN
pin separately from the PVIN pin, the VIN pin must be greater than 4.5 V, and the PVIN pin can range from as
low as 2.95 V to 17 V. When operating from a split rail, it is recommended to supply VIN from 5 V to 12 V, for
best performance. A voltage divider connected to the INH/UVLO pin can adjust either input voltage UVLO
appropriately. See the Programmable Undervoltage Lockout (UVLO) section of this datasheet for more
information.
16
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9.8 3.3 V PVIN Operation
Applications operating from a PVIN of 3.3 V must provide at least 4.5 V for VIN. It is recommended to supply VIN
from 5 V to 12 V, for best performance. See listeraure number SNVA692 for help creating 5 V from 3.3 V using a
small, simple charge pump device.
9.9 Power Good (PWRGD)
The PWRGD pin is an open drain output. Once the voltage on the SENSE+ pin is between 95% and 104% of the
set voltage, the PWRGD pin pull-down is released and the pin floats. The recommended pull-up resistor value is
between 10 kΩ and 100 kΩ to a voltage source that is 5.5 V or less. The PWRGD pin is in a defined state once
VIN is greater than 1.0 V, but with reduced current sinking capability. The PWRGD pin achieves full current
sinking capability once the VIN pin is above 4.5V. The PWRGD pin is pulled low when the voltage on SENSE+ is
lower than 91% or greater than 108% of the nominal set voltage. Also, the PWRGD pin is pulled low if the input
UVLO or thermal shutdown is asserted, the INH pin is pulled low, or the SS/TR pin is below 1.4 V.
9.10 SYNC_OUT
The LMZ31707 provides a 180° out-of-phase clock signal for applications requiring synchronization. The
SYNC_OUT pin produces a 50% duty cycle clock signal that is the same frequency as the device's switching
frequency, but is 180° out of phase. Operating two devices 180° out of phase reduces input and output voltage
ripple. The SYNC_OUT clock signal is compatible with other LMZ3 devices that have a CLK input.
9.11 Parallel Operation
Up to six LMZ31707 devices can be paralleled for increased output current. Multiple connections must be made
between the paralleled devices and the component selection is slightly different than for a stand-alone
LMZ31707 device. A typical LMZ31707 parallel schematic is shown in Figure 23. Refer to application note,
SNVA695 for information and design help when paralleling multiple LMZ31707 devices.
VIN = 12V
PWRGD
VIN
PVIN
SENSE+
220µF
22µF
0.1µF
VOUT
LMZ31707
22µF
100µF
100µF
VADJ
SS/TR
PGND
RSET
715 Ω
0.1µF
LMZ31707
PWRGD
SENSE+
VOUT
SYNC_OUT
RT/CLK
330µF
VADJ
VIN
PVIN
100µF
AGND
CSS
SS/TR
Voltage
Supervisor
CSH
INH
Control
ISHARE
5V
100µF
STSEL
ISHARE
RRT
169kΩ
INH/UVLO
Sync Freq
500KHz
INH/UVLO
SYNC_OUT
RT/CLK
VO = 1.8V
STSEL
AGND
RRT
169kΩ
PGND
Figure 23. Typical LMZ31707 Parallel Schematic
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9.12 Light Load Efficiency (LLE)
The LMZ31707 operates in pulse skip mode at light load currents to improve efficiency and decrease power
dissipation by reducing switching and gate drive losses.
These pulses may cause the output voltage to rise when there is no load to discharge the energy. For output
voltages < 1.5 V, a minimum load is required. The amount of required load can be determined by Equation 2. In
most cases the minimum current drawn by the load circuit will be enough to satisfy this load. Applications
requiring a load resistor to meet the minimum load, the added power dissipation will be ≤ 3.6 mW. A single 0402
size resistor across VOUT and PGND can be used.
(2)
When VOUT = 0.6 V and RSET = OPEN, the minimum load current is 600 µA.
9.13 Power-Up Characteristics
When configured as shown in the front page schematic, the LMZ31707 produces a regulated output voltage
following the application of a valid input voltage. During the power-up, internal soft-start circuitry slows the rate
that the output voltage rises, thereby limiting the amount of in-rush current that can be drawn from the input
source. Figure 24 shows the start-up waveforms for a LMZ31707, operating from a 5-V input (PVIN=VIN) and
with the output voltage adjusted to 1.8 V. Figure 25 shows the start-up waveforms for a LMZ31707 starting up
into a pre-biased output voltage. The waveforms were measured with a 5-A constant current load.
Figure 24. Start-Up Waveforms
18
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Figure 25. Start-up into Pre-bias
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9.14 Pre-Biased Start-Up
The LMZ31707 has been designed to prevent the low-side MOSFET from discharging a pre-biased output.
During pre-biased startup, the low-side MOSFET does not turn on until the high-side MOSFET has started
switching. The high-side MOSFET does not start switching until the slow start voltage exceeds the voltage on the
VADJ pin. Refer to Figure 25.
9.15 Remote Sense
The SENSE+ pin must be connected to VOUT at the load, or at the device pins.
Connecting the SENSE+ pin to VOUT at the load improves the load regulation performance of the device by
allowing it to compensate for any I-R voltage drop between its output pins and the load. An I-R drop is caused by
the high output current flowing through the small amount of pin and trace resistance. This should be limited to a
maximum of 300 mV.
NOTE
The remote sense feature is not designed to compensate for the forward drop of nonlinear
or frequency dependent components that may be placed in series with the converter
output. Examples include OR-ing diodes, filter inductors, ferrite beads, and fuses. When
these components are enclosed by the SENSE+ connection, they are effectively placed
inside the regulation control loop, which can adversely affect the stability of the regulator.
9.16 Thermal Shutdown
The internal thermal shutdown circuitry forces the device to stop switching if the junction temperature exceeds
175°C typically. The device reinitiates the power up sequence when the junction temperature drops below 165°C
typically.
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9.17 Output On/Off Inhibit (INH)
The INH pin provides electrical on/off control of the device. Once the INH pin voltage exceeds the threshold
voltage, the device starts operation. If the INH pin voltage is pulled below the threshold voltage, the regulator
stops switching and enters low quiescent current state. The INH pin has an internal pull-up current source,
allowing the user to float the INH pin for enabling the device.
If an application requires controlling the INH pin, use an open drain/collector device, or a suitable logic gate to
interface with the pin. Using a voltage superviser to control the INH pin allows control of the turn-on and turn-off
of the device as opposed to relying on the ramp up or down if the input voltage source.
Figure 26 shows the typical application of the inhibit function. Turning Q1 on applies a low voltage to the inhibit
control (INH) pin and disables the output of the supply, shown in Figure 27. If Q1 is turned off, the supply
executes a soft-start power-up sequence, as shown in Figure 28. A regulated output voltage is produced within
2 ms. The waveforms were measured with a 5-A constant current load.
INH/UVLO
Q1
INH
Control
AGND
STSEL
SS/TR
Figure 26. Typical Inhibit Control
Figure 27. Inhibit Turn-Off
20
Figure 28. Inhibit Turn-On
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9.18 Slow Start (SS/TR)
Connecting the STSEL pin to AGND and leaving SS/TR pin open enables the internal SS capacitor with a slow
start interval of approximately 1.2 ms. Adding additional capacitance between the SS pin and AGND increases
the slow start time. Increasing the slow start time will reduce inrush current seen by the input source and reduce
the current seen by the device when charging the output capacitors. To avoid the activation of current limit and
ensure proper start-up, the SS capacitor may need to be increased when operating near the maximum output
capacitance limit.
Figure 29 shows an additional SS capacitor connected to the SS/TR pin and the STSEL pin connected to AGND.
See Table 6 below for SS capacitor values and timing interval.
SS/TR
CSS
(Optional)
AGND
STSEL
Figure 29. Slow-Start Capacitor (CSS) and STSEL Connection
Table 6. Slow-Start Capacitor Values and Slow-Start Time
CSS (nF)
open
3.3
4.7
10
15
22
33
SS Time (msec)
1.2
2.1
2.5
3.8
5.1
7.0
9.8
9.19 Overcurrent Protection
For protection against load faults, the LMZ31707 incorporates output overcurrent protection. The overcurrent
protection mode can be selected using the OCP_SEL pin. Leaving the OCP_SEL pin open selects hiccup mode
and connecting it to AGND selects cycle-by-cycle mode. In hiccup mode, applying a load that exceeds the
regulator's overcurrent threshold causes the regulated output to shut down. Following shutdown, the module
periodically attempts to recover by initiating a soft-start power-up as shown in Figure 30. This is described as a
hiccup mode of operation, whereby the module continues in a cycle of successive shutdown and power up until
the load fault is removed. During this period, the average current flowing into the fault is significantly reduced
which reduces power dissipation. Once the fault is removed, the module automatically recovers and returns to
normal operation as shown in Figure 31.
In cycle-by-cycle mode, applying a load that exceeds the regulator's overcurrent threshold limits the output
current and reduces the output voltage as shown in Figure 32. During this period, the current flowing into the
fault remains high causing the power dissipation to stay high as well. Once the overcurrent condition is removed,
the output voltage returns to the set-point voltage as shown in Figure 33.
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Overcurrent Protection (continued)
22
Figure 30. Overcurrent Limiting (Hiccup)
Figure 31. Removal of Overcurrent (Hiccup)
Figure 32. Overcurrent Limiting (Cycle-by-Cycle)
Figure 33. Removal of Overcurrent (Cycle-by-Cycle)
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9.20 Synchronization (CLK)
An internal phase locked loop (PLL) has been implemented to allow synchronization between 200 kHz and
1200 kHz, and to easily switch from RT mode to CLK mode. To implement the synchronization feature, connect
a square wave clock signal to the RT/CLK pin with a duty cycle between 20% to 80%. The clock signal amplitude
must transition lower than 0.5 V and higher than 2.0 V. The start of the switching cycle is synchronized to the
falling edge of RT/CLK pin. In applications where both RT mode and CLK mode are needed, the device can be
configured as shown in Figure 34.
Before the external clock is present, the device works in RT mode and the switching frequency is set by RT
resistor. When the external clock is present, the CLK mode overrides the RT mode. The first time the CLK pin is
pulled above the RT/CLK high threshold (2.0 V), the device switches from RT mode to CLK mode and the
RT/CLK pin becomes high impedance as the PLL starts to lock onto the frequency of the external clock. It is not
recommended to switch from CLK mode back to RT mode because the internal switching frequency drops to
100 kHz first before returning to the switching frequency set by the RT resistor (RRT).
External Clock
200 kHz to 1200 kHz
RT/CLK
RRT
AGND
Figure 34. RT/CLK Configuration
The synchronization frequency must be selected based on the output voltages of the devices being
synchronized. Table 7 shows the allowable frequencies for a given range of output voltages. For the most
efficient solution, always synchronize to the lowest allowable frequency. For example, an application requires
synchronizing three LMZ31707 devices with output voltages of 1.0 V, 1.2 V and 1.8 V, all powered from
PVIN = 12 V. Table 7 shows that all three output voltages should be synchronized to 300 kHz.
Table 7. Synchronization Frequency vs Output Voltage
SYNCHRONIZATION
FREQUENCY (kHz)
PVIN = 12 V
PVIN = 5 V
VOUT RANGE (V)
VOUT RANGE (V)
MIN
MAX
MIN
MAX
200
0.6
1.3
0.6
1.5
300
0.8
2.0
0.6
4.3
400
1.1
2.5
0.6
4.3
500
1.4
3.4
0.6
4.3
600
1.6
5.0
0.7
4.3
700
1.9
5.5
0.8
4.3
800
2.1
5.5
0.9
4.3
900
2.4
5.5
1.0
4.3
1000
2.7
5.5
1.1
4.3
1100
2.9
5.5
1.3
4.3
1200
3.2
5.5
1.4
4.3
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9.21 Sequencing (SS/TR)
Many of the common power supply sequencing methods can be implemented using the SS/TR, INH and
PWRGD pins. The sequential method is illustrated in Figure 35 using two LMZ31707 devices. The PWRGD pin
of the first device is coupled to the INH pin of the second device which enables the second power supply once
the primary supply reaches regulation. Figure 36 shows sequential turn-on waveforms of two LMZ31707 devices.
INH/UVLO
VOUT1
VOUT
STSEL
PWRGD
INH/UVLO
VOUT2
VOUT
STSEL
PWRGD
Figure 35. Sequencing Schematic
Figure 36. Sequencing Waveforms
Simultaneous power supply sequencing can be implemented by connecting the resistor network of R1 and R2
shown in Figure 37 to the output of the power supply that needs to be tracked or to another voltage reference
source. The tracking voltage must exceed 750mV before VOUT2 reaches its set-point voltage. The PWRGD output
of the VOUT2 device may remain low if the tracking voltage does not exceed 1.4V.Figure 38 shows simultaneous
turn-on waveforms of two LMZ31707 devices. Use Equation 3 and Equation 4 to calculate the values of R1 and
R2.
R1 =
(VOUT2 ´ 12.6 )
0.6
R2 =
(kW )
(3)
0.6 ´ R1
(kW )
V
( OUT2 - 0.6 )
(4)
VOUT1
VOUT
INH/UVLO
STSEL
SS/TR
VOUT2
VOUT
INH/UVLO
R1
STSEL
SS/TR
R2
Figure 37. Simultaneous Tracking Schematic
24
Figure 38. Simultaneous Tracking Waveforms
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9.22 Programmable Undervoltage Lockout (UVLO)
The LMZ31707 implements internal UVLO circuitry on the VIN pin. The device is disabled when the VIN pin
voltage falls below the internal VIN UVLO threshold. The internal VIN UVLO rising threshold is 4.5 V(max) with a
typical hysteresis of 150 mV.
If an application requires either a higher UVLO threshold on the VIN pin or a higher UVLO threshold for a
combined VIN and PVIN, then the UVLO pin can be configured as shown in Figure 39 or Figure 40. Table 8 lists
standard values for RUVLO1 and RUVLO2 to adjust the VIN UVLO voltage up.
PVIN
PVIN
VIN
VIN
RUVLO1
RUVLO1
INH/UVLO
INH/UVLO
RUVLO2
RUVLO2
Figure 39. Adjustable VIN UVLO
Figure 40. Adjustable VIN and PVIN Undervoltage Lockout
Table 8. Standard Resistor values for Adjusting VIN UVLO
VIN UVLO (V)
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
RUVLO1 (kΩ)
68.1
68.1
68.1
68.1
68.1
68.1
68.1
68.1
68.1
68.1
68.1
RUVLO2 (kΩ)
21.5
18.7
16.9
15.4
14.0
13.0
12.1
11.3
10.5
9.76
9.31
Hysteresis (mV)
400
415
430
450
465
480
500
515
530
550
565
For a split rail application, if a secondary UVLO on PVIN is required, VIN must be ≥ 4.5V. Figure 41 shows the
PVIN UVLO configuration. Use Table 9 to select RUVLO1 and RUVLO2 for PVIN. If PVIN UVLO is set for less than
3.5 V, a 5.1-V zener diode should be added to clamp the voltage on the UVLO pin below 6 V.
> 4.5 V
VIN
PVIN
RUVLO1
INH/UVLO
RUVLO2
Figure 41. Adjustable PVIN Undervoltage Lockout, (VIN ≥4.5 V)
Table 9. Standard Resistor Values for Adjusting PVIN UVLO, (VIN ≥4.5 V)
PVIN UVLO (V)
2.9
3.0
3.5
4.0
4.5
RUVLO1 (kΩ)
68.1
68.1
68.1
68.1
68.1
RUVLO2 (kΩ)
47.5
44.2
34.8
28.7
24.3
Hysteresis (mV)
330
335
350
365
385
For higher PVIN UVLO voltages see
Table 8 for resistor values
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9.23 Layout Considerations
To achieve optimal electrical and thermal performance, an optimized PCB layout is required. Figure 42 thru
Figure 45, shows a typical PCB layout. Some considerations for an optimized layout are:
• Use large copper areas for power planes (PVIN, VOUT, and PGND) to minimize conduction loss and thermal
stress.
• Place ceramic input and output capacitors close to the device pins to minimize high frequency noise.
• Locate additional output capacitors between the ceramic capacitor and the load.
• Keep AGND and PGND separate from one another.
• Place RSET, RRT, and CSS as close as possible to their respective pins.
• Use multiple vias to connect the power planes to internal layers.
26
Figure 42. Typical Top-Layer Layout
Figure 43. Typical Layer-2 Layout
Figure 44. Typical Layer-3 Layout
Figure 45. Typical Bottom-Layer Layout
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9.24 EMI
The LMZ31707 is compliant with EN55022 Class B radiated emissions. Figure 46 and Figure 47 show typical
examples of radiated emissions plots for the LMZ31707 operating from 5V and 12V respectively. Both graphs
include the plots of the antenna in the horizontal and vertical positions.
Figure 46. Radiated Emissions 5-V Input, 1.8-V Output, 7-A
Load (EN55022 Class B)
Figure 47. Radiated Emissions 12-V Input, 1.8-V Output, 7A Load (EN55022 Class B)
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10 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision C (April 2018) to Revision D
•
Page
Added ESD Ratings information............................................................................................................................................. 2
Changes from Revision B (June 2017) to Revision C
Page
•
Added WEBENCH® design links for the LMZ31707.............................................................................................................. 1
•
Increased the peak reflow temperature and maximum number of reflows to JEDEC specifications for improved
manufacturability..................................................................................................................................................................... 2
•
Added Device Support section ............................................................................................................................................. 29
•
Added Mechanical, Packaging, and Orderable Information section .................................................................................... 30
Changes from Revision A (August 2013) to Revision B
•
28
Page
Added peak reflow and maximum number of reflows information ........................................................................................ 2
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11 Device and Documentation Support
11.1 Device Support
11.1.1 Development Support
11.1.1.1 Custom Design With WEBENCH® Tools
Click here to create a custom design using the LMZ31707 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.
11.2 Documentation Support
11.2.1 Related Documentation
For related documentation see the following:
Soldering Requirements for BQFN Packages
11.3 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.
11.4 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.
11.5 Trademarks
Eco-mode, E2E are trademarks of Texas Instruments.
WEBENCH is a registered trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.6 Electrostatic Discharge Caution
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
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11.7 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 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.
12.1 Tape and Reel Information
REEL DIMENSIONS
TAPE DIMENSIONS
K0
P1
B0 W
Reel
Diameter
Cavity
A0
B0
K0
W
P1
A0
Dimension designed to accommodate the component width
Dimension designed to accommodate the component length
Dimension designed to accommodate the component thickness
Overall width of the carrier tape
Pitch between successive cavity centers
Reel Width (W1)
QUADRANT ASSIGNMENTS FOR PIN 1 ORIENTATION IN TAPE
Sprocket Holes
Q1
Q2
Q1
Q2
Q3
Q4
Q3
Q4
User Direction of Feed
Pocket Quadrants
30
Device
Package
Type
Package
Drawing
Pins
SPQ
Reel
Diameter
(mm)
Reel
Width W1
(mm)
A0
(mm)
B0
(mm)
K0
(mm)
P1
(mm)
W
(mm)
Pin1
Quadrant
LMZ31707RVQR
B3QFN
RVQ
42
500
330.0
24.4
10.35
10.35
4.6
16.0
24.0
Q2
LMZ31707RVQT
B3QFN
RVQ
42
250
330.0
24.4
10.35
10.35
4.6
16.0
24.0
Q2
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TAPE AND REEL BOX DIMENSIONS
Width (mm)
W
L
H
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
LMZ31707RVQR
B3QFN
RVQ
42
500
383.0
353.0
58.0
LMZ31707RVQT
B3QFN
RVQ
42
250
383.0
353.0
58.0
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PACKAGE OPTION ADDENDUM
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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)
LMZ31707RVQR
ACTIVE
B3QFN
RVQ
42
500
RoHS Exempt
& Green
CU NIPDAU
Level-3-245C-168 HR
-40 to 85
(54020, LMZ31707)
LMZ31707RVQT
ACTIVE
B3QFN
RVQ
42
250
RoHS Exempt
& Green
CU NIPDAU
Level-3-245C-168 HR
-40 to 85
(54020, LMZ31707)
(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.
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.
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
1-Mar-2019
Addendum-Page 2
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
reproduction and display of these resources is prohibited. No license is granted to any other TI intellectual property right or to any third
party intellectual property right. TI disclaims responsibility for, and you will fully indemnify TI and its representatives against, any claims,
damages, costs, losses, and liabilities arising out of your use of these resources.
TI’s products are provided subject to TI’s Terms of Sale (www.ti.com/legal/termsofsale.html) or other applicable terms available either on
ti.com or provided in conjunction with such TI products. TI’s provision of these resources does not expand or otherwise alter TI’s applicable
warranties or warranty disclaimers for TI products.
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
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