LTM4622: Dual Ultrathin 2.5A or Single 5A Step
LTM4622
Dual Ultrathin 2.5A or
Single 5A Step-Down DC/DC
µModule Regulator
Description
Features
Complete Solution in <1cm2
nn Wide Input Voltage Range: 3.6V to 20V
nn 3.3V Input Compatible with V Tied to INTV
IN
CC
nn 0.6V to 5.5V Output Voltage
nn Dual 2.5A (3A Peak) or Single 5A Output Current
nn ±1.5% Maximum Total Output Voltage Regulation
Error Over Load, Line and Temperature
nn Current Mode Control, Fast Transient Response
nn External Frequency Synchronization
nn Multiphase Parallelable with Current Sharing
nn Output Voltage Tracking and Soft-Start Capability
nn Selectable Burst Mode® Operation
nn Overvoltage Input and Overtemperature Protection
nn Power Good Indicators
nn 6.25mm × 6.25mm × 1.82mm LGA and 6.25mm ×
6.25mm × 2.42mm BGA Packages
The LTM®4622 is a complete dual 2.5A step-down switching
mode µModule® (powermodule) regulator in a tiny ultrathin
6.25mm × 6.25mm × 1.82mm LGA and 6.25mm × 6.25mm
× 2.42mm BGA packages. Included in the package are the
switching controller, power FETs, inductor and support
components. Operating over an input voltage range of
3.6V to 20V, the LTM4622 supports an output voltage
range of 0.6V to 5.5V, set by a single external resistor. Its
high efficiency design delivers dual 2.5A continuous, 3A
peak, output current. Only a few ceramic input and output
capacitors are needed.
Applications
Fault protection features include input overvoltage, output
overcurrent and overtemperature protection.
nn
General Purpose Point-of-Load Conversion
Telecom, Networking and Industrial Equipment
nn Medical Diagnostic Equipment
nn Test and Debug Systems
The LTM4622 is RoHS compliant with Pb-free finish.
nn
L, LT, LTC, LTM, µModule, Burst Mode, PolyPhase, Linear Technology and the Linear logo are
registered trademarks and LTpowerCAD is a trademark of Linear Technology Corporation. All
other trademarks are the property of their respective owners.
nn
The LTM4622 supports selectable Burst Mode operation
and output voltage tracking for supply rail sequencing. Its
high switching frequency and current mode control enable
a very fast transient response to line and load changes
without sacrificing stability.
Typical Application
1.5V Output Efficiency vs Load Current
1.5V and 1V Dual Output DC/DC Step-Down µModule Regulator
95
90
4.7µF
25V
PGOOD1 PGOOD2
VIN
VOUT1
RUN1
RUN2 LTM4622 VOUT2
INTVCC
COMP1
SYNC/MODE
COMP2
TRACK/SS1
FB1
TRACK/SS2
FREQ
47µF
47µF
VOUT1
1V, 2.5A
VOUT2
1.5V, 2.5A
85
EFFICIENCY (%)
VIN
3.6V TO 20V
75
70
FB2
GND
80
65
40.2k
VIN = 5V
VIN = 12V
90.9k
60
4622 TA01a
0
0.5
1.0
1.5
2.0
LOAD CURRENT (A)
2.5
3
4622 TA01b
4622fc
For more information www.linear.com/LTM4622
1
LTM4622
Absolute Maximum Ratings
(Note 1)
VIN.............................................................. –0.3V to 22V
VOUT.............................................................. –0.3V to 6V
PGOOD1, PGOOD2...................................... –0.3V to 18V
RUN1, RUN2..................................... –0.3V to VIN + 0.3V
INTVCC, TRACK/SS1, TRACK/SS2............. –0.3V to 3.6V
SYNC/MODE, COMP1, COMP2,
FB1, FB2................................................ –0.3V to INTVCC
Pin Configuration
Operating Internal Temperature Range
(Note 2)................................................... –40°C to 125°C
Storage Temperature Range................... –55°C to 125°C
Peak Solder Reflow Body Temperature.................. 260°C
(See Pin Functions, Pin Configuration Table)
TOP VIEW
TOP VIEW
SYNC/
COMP2 GND MODE GND COMP1
SYNC/
COMP2 GND MODE GND COMP1
5
PGOOD2
FB2
INTVCC 4
TRACK/SS2
VIN 3
RUN2
2
VIN
VOUT2 1
5
PGOOD2
FB2
INTVCC 4
TRACK/SS2
VIN 3
RUN2
2
VIN
VOUT2 1
FREQ
PGOOD1
FB1
VIN
TRACK/SS1
RUN1
VIN
GND
VOUT1
A
A
B
C
D
E
LGA PACKAGE
25-LEAD (6.25mm × 6.25mm × 1.82mm)
TJMAX = 125°C, θJCtop = 17°C/W, θJCbottom = 11°C/W,
θJB + θBA = 22°C/W, θJA = 22°C/W,
WEIGHT = 0.21g
Order Information
B
C
D
E
BGA PACKAGE
25-LEAD (6.25mm × 6.25mm × 2.42mm)
TJMAX = 125°C, θJCtop = 17°C/W, θJCbottom = 11°C/W,
θJB + θBA = 22°C/W, θJA = 22°C/W,
WEIGHT = 0.25g
http://www.linear.com/product/LTM4622#orderinfo
PART MARKING*
PART NUMBER
PAD OR BALL FINISH
LTM4622EV#PBF
Au (RoHS)
FREQ
PGOOD1
FB1
VIN
TRACK/SS1
RUN1
VIN
GND
VOUT1
DEVICE
FINISH CODE
PACKAGE
TYPE
MSL
RATING
LTM4622V
e4
LGA
3
TEMPERATURE RANGE
(Note 2)
–40°C to 125°C
LTM4622IV#PBF
Au (RoHS)
LTM4622V
e4
LGA
3
–40°C to 125°C
LTM4622EY#PBF
SAC305 (RoHS)
LTM4622Y
e1
BGA
3
–40°C to 125°C
LTM4622IY#PBF
SAC305 (RoHS)
LTM4622Y
e1
BGA
3
–40°C to 125°C
LTM4622IY
SnPb (63/37)
LTM4622Y
e0
BGA
3
–40°C to 125°C
Consult Marketing for parts specified with wider operating temperature
ranges. *Device temperature grade is indicated by a label on the shipping
container. Pad or ball finish code is per IPC/JEDEC J-STD-609.
• Recommended LGA and BGA PCB Assembly and Manufacturing
Procedures:
www.linear.com/umodule/pcbassembly
• Pb-free and Non-Pb-free Part Markings:
www.linear.com/leadfree
• LGA and BGA Package and Tray Drawings:
www.linear.com/packaging
4622fc
2
For more information www.linear.com/LTM4622
LTM4622
Electrical
Characteristics
The l denotes the specifications which apply over the full internal
operating temperature range (Note 2). Specified as each individual output channel at TA = 25°C, VIN = 12V, unless otherwise noted per
the typical application shown in Figure 24.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Switching Regulator Section: per Channel
VIN
Input DC Voltage
l
3.6
VIN_3.3
3.3V Input DC Voltage
VOUT(RANGE)
VOUT(DC)
VIN = INTVCC
l
3.1
Output Voltage Range
VIN = 3.6V to 20V
l
Output Voltage, Total Variation
with Line and Load
l
CIN = 22µF, COUT = 100µF Ceramic, RFB = 40.2k,
MODE = INTVCC,VIN = 3.6V to 20V, IOUT = 0A to 2.5A
VRUN
RUN Pin On Threshold
RUN Threshold Rising
RUN Threshold Falling
IQ(VIN)
Input Supply Bias Current
VIN = 12V, VOUT = 1.5V, MODE = GND
VIN = 12V, VOUT = 1.5V, MODE = INTVCC
Shutdown, RUN1 = RUN2 = 0
11
500
45
mA
µA
µA
IS(VIN)
Input Supply Current
VIN = 12V, VOUT = 1.5V, IOUT = 2.5A
0.35
A
IOUT(DC)
Output Continuous Current Range VIN = 12V, VOUT = 1.5V (Note 3)
l
2.5
A
ΔVOUT (Line)/VOUT
Line Regulation Accuracy
VOUT = 1.5V, VIN = 3.6V to 20V, IOUT = 0A
l
0.01
0.1
%/V
VOUT = 1.5V, IOUT = 0A to 2.5A
l
0.2
1.0
%
ΔVOUT (Load)/VOUT Load Regulation Accuracy
20
V
3.3
3.5
V
5.5
V
1.477
1.50
1.523
V
1.20
0.97
1.27
1.00
1.35
1.03
V
V
0.6
0
VOUT(AC)
Output Ripple Voltage
IOUT = 0A, COUT = 100µF Ceramic, VIN = 12V,
VOUT = 1.5V
5
mV
ΔVOUT(START)
Turn-On Overshoot
IOUT = 0A, COUT = 100µF Ceramic, VIN = 12V,
VOUT = 1.5V
30
mV
tSTART
Turn-On Time
COUT = 100µF Ceramic, No Load, TRACK/SS = 0.01µF,
VIN = 12V, VOUT = 1.5V
4.3
ms
ΔVOUTLS
Peak Deviation for Dynamic Load
Load: 0% to 50% to 0% of Full Load, COUT = 100µF
Ceramic, VIN = 12V, VOUT = 1.5V
100
mV
tSETTLE
Settling Time for Dynamic Load
Step
Load: 0% to 50% to 0% of Full Load, COUT = 100µF
Ceramic, VIN = 12V, VOUT = 1.5V
20
µs
IOUTPK
Output Current Limit
VIN = 12V, VOUT = 1.5V
3
4
A
0.592
0.60
VFB
Voltage at FB Pin
IOUT = 0A, VOUT = 1.5V
IFB
Current at FB Pin
(Note 4)
RFBHI
Resistor Between VOUT and FB
Pins
ITRACK/SS
Track Pin Soft-Start Pull-Up
Current
TRACK/SS = 0V
1.4
tSS
Internal Soft-Start Time
10% to 90% Rise Time (Note 4)
400
l
60.00
60.40
0.608
V
±30
nA
60.80
kΩ
µA
700
μs
tON(MIN)
Minimum On-Time
(Note 4)
20
ns
tOFF(MIN)
Minimum Off-Time
(Note 4)
45
ns
VPGOOD
PGOOD Trip Level
VFB With Respect to Set Output
VFB Ramping Negative
VFB Ramping Positive
–8
8
RPGOOD
PGOOD Pull-Down Resistance
1mA Load
20
–14
14
%
%
Ω
4622fc
For more information www.linear.com/LTM4622
3
LTM4622
Electrical
Characteristics
The l denotes the specifications which apply over the full internal
operating temperature range (Note 2). Specified as each individual output channel at TA = 25°C, VIN = 12V, unless otherwise noted per
the typical application shown in Figure 24.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
3.1
3.3
3.5
UNITS
VINTVCC
Internal VCC Voltage
VIN = 3.6V to 20V
VINTVCC Load Reg
INTVCC Load Regulation
ICC = 0mA to 50mA
fOSC
Oscillator Frequency
fSYNC
Frequency Sync Range
With Respect to Set Frequency
±30
%
IMODE
MODE Input Current
MODE = INTVCC
–1.5
µA
1.3
1
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTM4622 is tested under pulsed load conditions such that
TJ ≈ TA. The LTM4622E is guaranteed to meet performance specifications
over the 0°C to 125°C internal operating temperature range. Specifications
over the full –40°C to 125°C internal operating temperature range are
assured by design, characterization and correlation with statistical process
controls. The LTM4622I is guaranteed to meet specifications over the
full –40°C to 125°C internal operating temperature range. Note that the
maximum ambient temperature consistent with these specifications is
determined by specific operating conditions in conjunction with board
layout, the rated package thermal resistance and other environmental
factors.
V
%
MHz
Note 3: See output current derating curves for different VIN, VOUT and TA.
Note 4: 100% tested at wafer level.
Note 5: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
4622fc
4
For more information www.linear.com/LTM4622
LTM4622
Typical Performance Characteristics
Efficiency vs Load Current
at 12VIN
Efficiency vs Load Current
at 3.3VIN
95
95
90
90
90
85
85
85
80
75
70
OUTPUT:
3.3V, 2MHz
1.8V, 1MHz
1.2V, 1MHz
65
60
0
0.5
EFFICIENCY (%)
95
EFFICIENCY (%)
EFFICIENCY (%)
Efficiency vs Load Current
at 5VIN
80
75
OUTPUT:
5.0V, 2.5MHz
2.5V, 1.5MHz
1.5V, 1MHz
1.0V, 1MHz
70
2.5V, 1.5MHz
1.5V, 1MHz
1.0V, 1MHz
1.0
1.5
2.0
LOAD CURRENT (A)
2.5
65
3
60
0
0.5
4622 G01
Burst Mode Efficiency,
12VIN, 1.5VOUT
1.0
1.5
2.0
LOAD CURRENT (A)
75
70
3.3V, 2MHz
1.8V, 1MHz
1.2V, 1MHz
2.5
80
OUTPUT:
2.5V, 1.5MHz
1.5V, 1MHz
1.0V, 1MHz
65
60
3
4622 G02
0
0.5
1.0
1.5
2.0
LOAD CURRENT (A)
1.8V, 1MHz
1.2V, 1MHz
2.5
3
4622 G02b
1.2V Output Transient Response
1V Output Transient Response
100
90
Burst Mode Operation
EFFICIENCY (%)
80
70
VOUT
100mV/DIV
AC-COUPLED
VOUT
100mV/DIV
AC-COUPLED
LOAD STEP
1A/DIV
LOAD STEP
1A/DIV
60
50
CCM
40
30
20
10
0
0.01
0.1
LOAD CURRENT (A)
4622 G04
VIN = 12V
20μs/DIV
VOUT = 1V
FS = 1MHz
OUTPUT CAPACITOR = 1 × 47µF CERAMIC
LOAD STEP = 1.25A TO 2.5A
4622 G05
VIN = 12V
20µs/DIV
VOUT = 1.2V
FS = 1MHz
OUTPUT CAPACITOR = 1 × 47µF CERAMIC
LOAD STEP = 1.25A TO 2.5A
1.8V Output Transient Response
2.5V Output Transient Response
1
4622 G03
1.5V Output Transient Response
VOUT
100mV/DIV
AC-COUPLED
LOAD STEP
1A/DIV
4622 G06
VIN = 12V
20µs/DIV
VOUT = 1.5V
FS = 1MHz
OUTPUT CAPACITOR = 1 × 47µF CERAMIC
LOAD STEP = 1.25A TO 2.5A
VOUT
100mV/DIV
AC-COUPLED
VOUT
100mV/DIV
AC-COUPLED
LOAD STEP
1A/DIV
LOAD STEP
1A/DIV
4622 G07
VIN = 12V
20µs/DIV
VOUT = 1.8V
FS = 1MHz
OUTPUT CAPACITOR = 1 × 47µF CERAMIC
LOAD STEP = 1.25A TO 2.5A
4622 G08
VIN = 12V
20µs/DIV
VOUT = 2.5V
FS = 1.5MHz
OUTPUT CAPACITOR = 1 × 47µF CERAMIC
LOAD STEP = 1.25A TO 2.5A
4622fc
For more information www.linear.com/LTM4622
5
LTM4622
Typical Performance Characteristics
Start-Up with No Load Current
Applied
5V Output Transient Response
3.3V Output Transient Response
SW
10V/DIV
VOUT
100mV/DIV
AC-COUPLED
VOUT
100mV/DIV
AC-COUPLED
VOUT
1V/DIV
LOAD STEP
1A/DIV
LOAD STEP
1A/DIV
4622 G10
VIN = 12V
20µs/DIV
VOUT = 5V
FS = 2.5MHz
OUTPUT CAPACITOR = 1 × 47µF CERAMIC
LOAD STEP = 1.25A TO 2.5A
4622 G09
20µs/DIV
VIN = 12V
VOUT = 3.3V
FS = 2MHz
OUTPUT CAPACITOR = 1 × 47µF CERAMIC
LOAD STEP = 1.25A TO 2.5A
RUN
10V/DIV
4622 G11
VIN = 12V
20ms/DIV
VOUT = 1.8V
FS = 1MHz
INPUT CAPACITOR = 1 × 22µF
OUTPUT CAPACITOR = 1 × 22µF + 1 × 47µF CERAMIC
SOFT-START CAP = 0.1µF
Short-Circuit with 2.5A Load
Current Applied
Short-Circuit with No Load
Current Applied
Start-Up with 2.5A Load Current
Applied
SW
10V/DIV
SW
10V/DIV
SW
10V/DIV
VOUT
1V/DIV
VOUT
1V/DIV
VOUT
1V/DIV
RUN
10V/DIV
IIN
2A/DIV
IIN
500mA/DIV
4622 G12
VIN = 12V
200ms/DIV
VOUT = 1.8V
FS = 1MHz
INPUT CAPACITOR = 1 × 22µF
OUTPUT CAPACITOR = 1 × 22µF + 1 × 47µF CERAMIC
SOFT-START CAP = 0.1µF
4622 G13
VIN = 12V
20µs/DIV
VOUT = 1.8V
FS = 1MHz
INPUT CAPACITOR = 1 × 22µF
OUTPUT CAPACITOR = 1 × 22µF + 1 × 47µF CERAMIC
4622 G14
VIN = 12V
20µs/DIV
VOUT = 1.8V
FS = 1MHz
INPUT CAPACITOR = 1 × 22µF
OUTPUT CAPACITOR = 1 × 22µF + 1 × 47µF CERAMIC
Recover from Short-Circuit with
No Load Current Applied
Steady-State Output Voltage
Ripple
Start-Up into Pre-Biased Output
SW
10V/DIV
SW
10V/DIV
VOUT
10mV/DIV
AC-COUPLED
VOUT
1V/DIV
VOUT
1V/DIV
SW
5V/DIV
IIN
2A/DIV
4622 G15
VIN = 12V
20µs/DIV
VOUT = 1.8V
FS = 1MHz
INPUT CAPACITOR = 1 × 22µF
OUTPUT CAPACITOR = 1 × 22µF + 1 × 47µF CERAMIC
RUN
10V/DIV
4622 G16
VIN = 12V
1µs/DIV
VOUT = 1.8V
FS = 1MHz
INPUT CAPACITOR = 1 × 22µF
OUTPUT CAPACITOR = 1 × 22µF + 1 × 47µF CERAMIC
4622 G17
VIN = 12V
50ms/DIV
VOUT = 1.8V
FS = 1MHz
INPUT CAPACITOR = 1 × 22µF
OUTPUT CAPACITOR = 1 × 22µF + 1 × 47µF CERAMIC
4622fc
6
For more information www.linear.com/LTM4622
LTM4622
Pin Functions
PACKAGE ROW AND COLUMN LABELING MAY VARY
AMONG µModule PRODUCTS. REVIEW EACH PACKAGE
LAYOUT CAREFULLY.
VIN (A2, B3, D3, E2): Power Input Pins. Apply input voltage
between these pins and GND pins. Recommend placing
input decoupling capacitance directly between VIN pins
and GND pins.
GND (C1 to C2, B5, D5): Power Ground Pins for Both
Input and Output Returns.
INTVCC (C3): Internal 3.3V Regulator Output. The internal
power drivers and control circuits are powered from this
voltage. This pin is internally decoupled to GND with a
2.2µF low ESR ceramic capacitor. No additional external
decoupling capacitor needed.
SYNC/MODE (C5): Mode Select and External Synchronization Input. Tie this pin to ground to force continuous
synchronous operation at all output loads. Floating this
pin or tying it to INTVCC enables high efficiency Burst
Mode operation at light loads. Drive this pin with a clock
to synchronize the LTM4622 switching frequency. An
internal phase-locked loop will force the bottom power
NMOS’s turn on signal to be synchronized with the rising
edge of the clock signal. When this pin is driven with a
clock, forced continuous mode is automatically selected.
VOUT1 (D1, E1), VOUT2 (A1, B1): Power Output Pins
of Each Switching Mode Regulator. Apply output load
between these pins and GND pins. Recommend placing
output decoupling capacitance directly between these
pins and GND pins.
FREQ (C4): Frequency is set internally to 1MHz. An
external resistor can be placed from this pin to GND to
increase frequency, or from this pin to INTVCC to reduce
frequency. See the Applications Information section for
frequency adjustment.
RUN1 (D2), RUN2 (B2): Run Control Input of Each Switching Mode Regulator Channel. Enables chip operation by
tying RUN above 1.27V. Tying this pin below 1V shuts
down the specific regulator channel. Do not float this pin.
PGOOD1 (D4), PGOOD2 (B4): Output Power Good with
Open-Drain Logic of Each Switching Mode Regulator
Channel. PGOOD is pulled to ground when the voltage
on the FB pin is not within ±8% (typical) of the internal
0.6V reference.
TRACK/SS1 (E3), TRACK/SS2 (A3): Output Tracking
and Soft-Start Pin of Each Switching Mode Regulator
Channel. It allows the user to control the rise time of the
output voltage. Putting a voltage below 0.6V on this pin
bypasses the internal reference input to the error amplifier, instead it servos the FB pin to the TRACK voltage.
Above 0.6V, the tracking function stops and the internal
reference resumes control of the error amplifier. There’s
an internal 1.4µA pull-up current from INTVCC on this pin,
so putting a capacitor here provides soft-start function.
A default internal soft-start ramp forces a minimum softstart time of 400µs.
FB1 (E4), FB2 (A4): The Negative Input of the Error Amplifier for Each Switching Mode Regulator Channel. Internally, this pin is connected to VOUT with a 60.4k precision
resistor. Different output voltages can be programmed
with an additional resistor between FB and GND pins. In
PolyPhase® operation, tying the FB pins together allows
for parallel operation. See the Applications Information
section for details.
COMP1 (E5), COMP2 (A5): Current Control Threshold
and Error Amplifier Compensation Point of Each Switching Mode Regulator Channel. The current comparator’s
trip threshold is linearly proportional to this voltage,
whose normal range is from 0.3V to 1.8V. Tie the COMP
pins together for parallel operation. The device is internal
compensated. Do not drive this pin.
4622fc
For more information www.linear.com/LTM4622
7
LTM4622
Block Diagram
VOUT1 VOUT2
60.4k
FB1
60.4k
60.4k
FB2
40.2k
PGOOD1
10k
PGOOD2
10k
INTVCC
INTVCC
VIN
2.2µF
0.22µF
22µF
SYNC/MODE
TRACK/SS1
1µH
1µF
TRACK/SS2
VIN
3.6V TO 20V
VOUT1
1.2V
2.5A
VOUT1
0.1µF
0.1µF
INTVCC
47µF
GND
RUN1
RUN2
COMP1
0.22µF
POWER CONTROL
INTERNAL
COMP
1µH
VOUT2
1.5V
2.5A
VOUT2
1µF
COMP2
47µF
GND
INTERNAL
COMP
FREQ
324k
4622 BD
Figure 1. Simplified LTM4622 Block Diagram
Decoupling Requirements
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
CIN
External Input Capacitor Requirement
(VIN = 3.6V to 20V, VOUT = 1.5V)
IOUT = 2.5A
4.7
10
µF
COUT
External Output Capacitor Requirement
(VIN = 3.6V to 20V, VOUT = 1.5V)
IOUT = 2.5A
22
47
µF
4622fc
8
For more information www.linear.com/LTM4622
LTM4622
Operation
The LTM4622 is a dual output standalone non-isolated
switch mode DC/DC power supply. It can deliver two 2.5A
DC, 3A peak output current with few external input and
output ceramic capacitors. This module provides dual
precisely regulated output voltage programmable via
two external resistor from 0.6V to 5.5V over 3.6V to 20V
input voltage range. With INTVCC tied to VIN, this module
is able to operate from 3.3V input. The typical application
schematic is shown in Figure 24.
The LTM4622 contains an integrated controlled on-time
valley current mode regulator, power MOSFETs, inductor,
and other supporting discrete components. The default
switching frequency is 1MHz. For output voltages between
2.5V and 5.5V, an external resistor is required between
FREQ and SGND pins to set the operating frequency to
higher frequency to optimize inductor current ripple. For
switching noise-sensitive applications, the switching
frequency can be adjusted by external resistors and the
μModule regulator can be externally synchronized to a
clock within ±30% of the set frequency. See the Applications Information section.
With current mode control and internal feedback loop
Applications Information
The typical LTM4622 application circuit is shown in
Figure 24. External component selection is primarily
determined by the input voltage, the output voltage and
the maximum load current. Refer to Table 6 for specific
external capacitor requirements for a particular application.
VIN to VOUT Step-Down Ratios
There are restrictions in the maximum VIN and VOUT step
down ratio that can be achieved for a given input voltage
due to the minimum off-time and minimum on-time limits
of the regulator. The minimum off-time limit imposes a
maximum duty cycle which can be calculated as
compensation, the LTM4622 module has sufficient
stability margins and good transient performance with
a wide range of output capacitors, even with all ceramic
output capacitors.
Current mode control provides cycle-by-cycle fast current limiting. An internal overvoltage and undervoltage
comparators pull the open-drain PGOOD output low if the
output feedback voltage exits a ±8% window around the
regulation point. Furthermore, an input overvoltage protection been utilized by shutting down both power MOSFETs
when VIN rises above 22.5V to protect internal devices.
Multiphase operation can be easily employed by connecting
SYNC pin to an external oscillator. Up to 6 phases can be
paralleled to run simultaneously a good current sharing
guaranteed by current mode control loop.
Pulling the RUN pin below 1V forces the controller into
its shutdown state, turning off both power MOSFETs and
most of the internal control circuitry. At light load currents,
Burst Mode operation can be enabled to achieve higher
efficiency compared to continuous mode (CCM) by setting MODE pin to INTVCC. The TRACK/SS pin is used for
power supply tracking and soft-start programming. See
the Applications Information section.
where tOFF(MIN) is the minimum off-time, 45ns typical for
LTM4622, and fSW is the switching frequency. Conversely
the minimum on-time limit imposes a minimum duty cycle
of the converter which can be calculated as
DMIN = tON(MIN) • fSW
where tON(MIN) is the minimum on-time, 20ns typical for
LTM4622. In the rare cases where the minimum duty
cycle is surpassed, the output voltage will still remain
in regulation, but the switching frequency will decrease
from its programmed value. Note that additional thermal
derating may be applied. See the Thermal Considerations
and Output Current Derating section in this data sheet.
DMAX = 1 – tOFF(MIN) • fSW
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LTM4622
Applications Information
Output Voltage Programming
Output Decoupling Capacitors
The PWM controller has an internal 0.6V reference voltage.
As shown in the Block Diagram, a 60.4k 0.5% internal
feedback resistor connects VOUT and FB pins together.
Adding a resistor RFB from FB pin to GND programs the
output voltage:
With an optimized high frequency, high bandwidth design,
only single piece of 22µF low ESR output ceramic capacitor is required for each LTM4622 output to achieve low
output voltage ripple and very good transient response.
Additional output filtering may be required by the system designer, if further reduction of output ripples or
dynamic transient spikes is required. Table 6 shows a
matrix of different output voltages and output capacitors
to minimize the voltage droop and overshoot during a
1.25A (50%) load step transient. Multiphase operation
will reduce effective output ripple as a function of the
number of phases. Application Note 77 discusses this
noise reduction versus output ripple current cancellation, but the output capacitance will be more a function
of stability and transient response. The Linear Technology
LTpowerCAD™ Design Tool is available to download online
for output ripple, stability and transient response analysis
and calculating the output ripple reduction as the number
of phases implemented increases by N times.
RFB =
0.6V
• 60.4k
VOUT – 0.6V
Table 1. VFB Resistor Table vs Various Output Voltages
VOUT (V)
0.6
1.0
1.2
1.5
1.8
2.5
3.3
5.0
RFB (k)
OPEN
90.9
60.4
40.2
30.1
19.1
13.3
8.25
Pease note that for 2.5 to 5V output, a higher operating
frequency is required to optimize inductor current ripple.
See Operating Frequency section.
For parallel operation of N-channels LTM4622, the following equation can be used to solve for RFB:
RFB =
0.6V
60.4k
•
VOUT – 0.6V
N
Burst Mode Operation
Input Decoupling Capacitors
The LTM4622 module should be connected to a low ACimpedance DC source. For each regulator channel, one piece
4.7µF input ceramic capacitor is required for RMS ripple
current decoupling. Bulk input capacitor is only needed
when the input source impedance is compromised by long
inductive leads, traces or not enough source capacitance.
The bulk capacitor can be an electrolytic aluminum capacitor and polymer capacitor.
Without considering the inductor current ripple, for each
output, the RMS current of the input capacitor can be
estimated as:
ICIN(RMS) =
IOUT(MAX)
η%
• D • (1–D)
where is the estimated efficiency of the power module.
In applications where high efficiency at intermediate current
are more important than output voltage ripple, Burst Mode
operation could be used by connecting SYNC/MODE pin
to INTVCC to improve light load efficiency. In Burst Mode
operation, a current reversal comparator (IREV) detects
the negative inductor current and shuts off the bottom
power MOSFET, resulting in discontinuous operation and
increased efficiency. Both power MOSFETs will remain
off and the output capacitor will supply the load current
until the COMP voltage rises above the zero current level
to initiate another cycle.
Force Continuous Current Mode (CCM) Operation
In applications where fixed frequency operation is more
critical than low current efficiency, and where the lowest
output ripple is desired, forced continuous operation
should be used. Forced continuous operation can be
enabled by tying the SYNC/MODE pin to GND. In this
mode, inductor current is allowed to reverse during low
output loads, the COMP voltage is in control of the current
comparator threshold throughout, and the top MOSFET
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Applications Information
always turns on with each oscillator pulse. During start-up,
forced continuous mode is disabled and inductor current
is prevented from reversing until the LTM4622’s output
voltage is in regulation.
Operating Frequency
The operating frequency of the LTM4622 is optimized to
achieve the compact package size and the minimum output ripple voltage while still keeping high efficiency. The
default operating frequency is internally set to 1MHz. In
most applications, no additional frequency adjusting is
required.
If any operating frequency other than 1MHz is required
by application, the operating frequency can be increased
by adding a resistor, RFSET, between the FREQ pin and
SGND, as shown in Figure 26. The operating frequency
can be calculated as:
f (Hz ) =
3.2e11
324k||RFSET ( Ω )
To reduce switching current ripple, 1.5MHz to 2.5MHz
operating frequency is required for 2.5V to 5.5V output
with RFSET to SGND.
VOUT
0.6V to
1.8V
2.5V
3.3V
5V
fSW
1MHz
1.5MHz
2MHz
2.5MHz
RFSET
Open
649kΩ
324kΩ
215kΩ
The operating frequency can also be decreased by adding
a resistor between the FREQ pin and INTVCC, calculated as:
f (Hz ) = 1MHz –
5.67e11
RFSET ( Ω )
external clock frequency range must be within ±30%
around the set operating frequency. A pulse detection
circuit is used to detect a clock on the SYNC/MODE pin
to turn on the phase-locked loop. The pulse width of the
clock has to be at least 100ns. The clock high level must
be above 2V and clock low level below 0.3V. The presence
of an external clock will place both regulator channels into
forced continuous mode operation. During the start-up of
the regulator, the phase-locked loop function is disabled.
Multiphase Operation
For output loads that demand more than 2.5A of current,
two outputs in the LTM4622 or even multiple LTM4622s
can be paralleled to run out of phase to provide more output
current without increasing input and output voltage ripples.
A multiphase power supply significantly reduces the
amount of ripple current in both the input and output capacitors. The RMS input ripple current is reduced by, and
the effective ripple frequency is multiplied by, the number
of phases used (assuming that the input voltage is greater
than the number of phases used times the output voltage).
The output ripple amplitude is also reduced by the number
of phases used when all of the outputs are tied together
to achieve a single high output current design.
The two switching mode regulator channels inside the
LTM4622 are internally set to operate 180° out of phase.
Multiple LTM4622s could easily operate 90 degrees, 60
degrees or 45 degrees shift which corresponds to 4-phase,
6-phase or 8-phase operation by letting SYNC/MODE of the
LTM4622 synchronize to an external multiphase oscillator
like LTC®6902. Figure 2 shows a 4-phase design example
for clock phasing.
33.2k, 1.5MHz
The programmable operating frequency range is from
800kHz to 4MHz.
3.3V INTVCC
V+
SET
PH
MOD
SYNC/MODE VOUT1
VOUT2
LTC6902
Frequency Synchronization
The power module has a phase-locked loop comprised
of an internal voltage controlled oscillator and a phase
detector. This allows the internal top MOSFET turn-on
to be locked to the rising edge of the external clock. The
DIV
OUT1
GND
OUT2
0°
90°
SYNC/MODE VOUT1
VOUT2
0°
10A
180°
90°
270°
4622 F02
Figure 2. Example of Clock Phasing for 4-Phase
Operation with LTC6902
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LTM4622
Applications Information
The LTM4622 device is an inherently current mode controlled device, so parallel modules will have very good
current sharing. This will balance the thermals on the
design. Please tie RUN, TRACK/SS, FB and COMP pin of
each paralleling channel together. Figure 28 shows an
example of parallel operation and pin connection.
INPUT RMS Ripple Current Cancellation
Application Note 77 provides a detailed explanation of
multiphase operation. The input RMS ripple current cancellation mathematical derivations are presented, and a
graph is displayed representing the RMS ripple current
reduction as a function of the number of interleaved phases.
Figure 3 shows this graph.
capacitor on the TRACK/SS pin will program the ramp rate
of the output voltage. An internal 1.4µA current source
will charge up the external soft-start capacitor towards
INTVCC voltage. When the TRACK/SS voltage is below
0.6V, it will take over the internal 0.6V reference voltage
to control the output voltage. The total soft-start time
can be calculated as:
tSS = 0.6 •
CSS
1.4µA
where CSS is the capacitance on the TRACK/SS pin. Current
foldback and force continuous mode are disabled during
the soft-start process.
Soft-Start and Output Voltage Tracking
The LTM4622 has internal 400μs soft-start time when
TRACK/SS leave floating.
The TRACK/SS pin provides a means to either soft-start
the regulator or track it to a different power supply. A
Output voltage tracking can also be programmed externally
using the TRACK/SS pin. The output can be tracked up and
0.60
0.55
0.50
1-PHASE
2-PHASE
3-PHASE
4-PHASE
6-PHASE
RMS INPUT RIPPLE CURRENT
DC LOAD CURRENT
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9
DUTY FACTOR (VOUT/VIN)
4622 F03
Figure 3. Input RMS Current Ratios to DC Load Current as a Function of Duty Cycle
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down with another regulator. Figure 4 and Figure 5 show
an example waveform and schematic of a Ratiometric
tracking where the slave regulator’s output slew rate is
proportional to the master’s.
Since the slave regulator’s TRACK/SS is connected to
the master’s output through a RTR(TOP)/RTR(BOT) resistor
RTR(BOT) is the resistor divider on the TRACK/SS pin of
the slave regulator, as shown in Figure 5.
Following the upper equation, the master’s output slew
rate (MR) and the slave’s output slew rate (SR) in Volts/
Time is determined by:
RFB(SL)
MR
=
SR
OUTPUT VOLTAGE
MASTER OUTPUT
SLAVE OUTPUT
4622 F04
Figure 4. Output Ratiometric Tracking Waveform
VOUT1
R TR(TOP) +R TR(BOT)
For example, VOUT(MA) = 1.5V, MR = 1.4V/1ms and VOUT(SL)
= 1.2V, SR = 1.2V/1ms. From the equation, we could solve
out that RTR(TOP) = 60.4k and RTR(BOT) = 40.2k is a good
combination for the Ratiometric tracking.
TIME
VIN
4V TO 20V
RFB(SL) +60.4k
R TR(BOT)
PGOOD1 PGOOD2
VIN
VOUT1
RUN1
RUN2 LTM4622 VOUT2
INTVCC
COMP1
SYNC/MODE
COMP2
TRACK/SS1
FB1
10µF
25V
60.4k
TRACK/SS2
FREQ
0.1µF
47µF
4V
47µF
4V
VOUT1
1.5V, 2.5A
VOUT2
1.2V, 2.5A
FB2
GND
60.4k
40.2k
40.2k
4622 F05
The TRACK pins will have the 1.5µA current source on
when a resistive divider is used to implement tracking on
that specific channel. This will impose an offset on the
TRACK pin input. Smaller values resistors with the same
ratios as the resistor values calculated from the above
equation can be used. For example, where the 60.4k is
used then a 6.04k can be used to reduce the TRACK pin
offset to a negligible value.
The Coincident output tracking can be recognized as a
special Ratiometric output tracking which the master’s
output slew rate (MR) is the same as the slave’s output
slew rate (SR), as waveform shown in Figure 6.
Figure 5. Example Schematic of Ratiometric
Output Voltage Tracking
VOUT(SL) •
RFB(SL)
RFB(SL) +60.4k
VOUT(MA) •
MASTER OUTPUT
OUTPUT VOLTAGE
divider and its voltage used to regulate the slave output
voltage when TRACK/SS voltage is below 0.6V, the slave
output voltage and the master output voltage should satisfy
the following equation during the start-up.
SLAVE OUTPUT
=
R TR(BOT)
TIME
R TR(TOP) +R TR(BOT)
4622 F06
Figure 6. Output Coincident Tracking Waveform
The RFB(SL) is the feedback resistor and the RTR(TOP)/
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LTM4622
Applications Information
From the equation, we could easily find out that, in the
Coincident tracking, the slave regulator’s TRACK/SS pin
resistor divider is always the same as its feedback divider.
RFB(SL)
=
R TR(BOT)
RFB(SL) +60.4k R TR(TOP) +R TR(BOT)
For example, RTR(TOP) = 60.4k and RTR(BOT) = 60.4k is a
good combination for Coincident tracking for VOUT(MA) =
1.5V and VOUT(SL) = 1.2V application.
Power Good
The PGOOD pins are open drain pins that can be used to
monitor valid output voltage regulation. This pin monitors
a ±8% window around the regulation point. A resistor can
be pulled up to a particular supply voltage for monitoring.
To prevent unwanted PGOOD glitches during transients
or dynamic VOUT changes, the LTM4622’s PGOOD falling
edge includes a blanking delay of approximately 40µs.
Pre-Biased Output Start-Up
There may be situations that require the power supply to
start up with a pre-bias on the output capacitors. In this
case, it is desirable to start up without discharging that
output pre-bias. The LTM4622 can safely power up into
a pre-biased output without discharging it.
The LTM4622 accomplishes this by forcing discontinuous
mode (DCM) operation until the TRACK/SS pin voltage
reaches 0.6V reference voltage. This will prevent the BG
from turning on during the pre-biased output start-up
which would discharge the output. Please do not pre-bias
LTM4622 with a voltage higher than INTVCC (3.3V) voltage.
Overtemperature Protection
The internal overtemperature protection monitors the junction temperature of the module. If the junction temperature
reaches approximately 160°C, both power switches will be
turned off until the temperature drops about 15°C cooler.
Stability compensation
Input Overvoltage Protection
The LTM4622 module internal compensation loop is designed and optimized for low ESR ceramic output capacitors
only application. Table 7 is provided for most application
requirements. The LTpowerCAD Design Tool is available
to down for control loop optimization.
In order to protect the internal power MOSFET devices
against transient voltage spikes, the LTM4622 constantly
monitors each VIN pin for an overvoltage condition. When
VIN rises above 22.5V, the regulator suspends operation
by shutting off both power MOSFETs on the corresponding channel. Once VIN drops below 21.5V, the regulator
immediately resumes normal operation. The regulator
executes its soft-start function when exiting an overvoltage condition.
RUN Enable
Pulling the RUN pin to ground forces the LTM4622 into
its shutdown state, turning off both power MOSFETs and
most of its internal control circuitry. Trying the RUN pin
voltage above 1.27V will turn on the entire chip.
Low Input Application
The LTM4622 is capable to run from 3.3V input when
the VIN pin is tied to INTVCC pin. See Figure 27 for the
application circuit. Please note the INTVCC pin has 3.6V
ABSMAX voltage rating.
Thermal Considerations and Output Current Derating
The thermal resistances reported in the Pin Configuration section of the data sheet are consistent with those
parameters defined by JESD51-9 and are intended for
use with finite element analysis (FEA) software modeling
tools that leverage the outcome of thermal modeling,
simulation, and correlation to hardware evaluation performed on a µModule package mounted to a hardware test
4622fc
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JUNCTION-TO-AMBIENT THERMAL RESISTANCE COMPONENTS
CASE (TOP)-TO-AMBIENT
RESISTANCE
JUNCTION-TO-CASE (TOP)
RESISTANCE
JUNCTION
JUNCTION-TO-BOARD RESISTANCE
AMBIENT
JUNCTION-TO-CASE
CASE (BOTTOM)-TO-BOARD
(BOTTOM) RESISTANCE
RESISTANCE
BOARD-TO-AMBIENT
RESISTANCE
4622 F07
µMODULE DEVICE
Figure 7. Graphical Representation of JESD 51-12 Thermal Coefficients
board—also defined by JESD51-9 (Test Boards for Area
Array Surface Mount Package Thermal Measurements).
The motivation for providing these thermal coefficients in
found in JESD51-12 (Guidelines for Reporting and Using
Electronic Package Thermal Information).
Many designers may opt to use laboratory equipment
and a test vehicle such as the demo board to anticipate
the µModule regulator’s thermal performance in their application at various electrical and environmental operating
conditions to compliment any FEA activities. Without FEA
software, the thermal resistances reported in the Pin Configuration section are in-and-of themselves not relevant to
providing guidance of thermal performance; instead, the
derating curves provided in the data sheet can be used in
a manner that yields insight and guidance pertaining to
one’s application usage, and can be adapted to correlate
thermal performance to one’s own application.
The Pin Configuration section typically gives four thermal
coefficients explicitly defined in JESD 51-12; these coefficients are quoted or paraphrased below:
1.θJA, the thermal resistance from junction to ambient, is
the natural convection junction-to-ambient air thermal
resistance measured in a one cubic foot sealed enclosure. This environment is sometimes referred to as still
air although natural convection causes the air to move.
This value is determined with the part mounted to a
JESD 51-9 defined test board, which does not reflect
an actual application or viable operating condition.
2.θJCbottom, the thermal resistance from junction to ambient, is the natural convection junction-to-ambient air
thermal resistance measured in a one cubic foot sealed
enclosure. This environment is sometimes referred to
as still air although natural convection causes the air to
move. This value is determined with the part mounted to
a JESD 51-9 defined test board, which does not reflect
an actual application or viable operating condition.
3.θJCtop, the thermal resistance from junction to top of
the product case, is determined with nearly all of the
component power dissipation flowing through the top
of the package. As the electrical connections of the
typical µModule are on the bottom of the package, it
is rare for an application to operate such that most of
the heat flows from the junction to the top of the part.
As in the case of θJCbottom, this value may be useful
for comparing packages but the test conditions don’t
generally match the user’s application.
4.θJB, the thermal resistance from junction to the printed
circuit board, is the junction-to-board thermal resistance
where almost all of the heat flows through the bottom of
the µModule and into the board, and is really the sum of
the θJCbottom and the thermal resistance of the bottom
of the part through the solder joints and through a portion of the board. The board temperature is measured a
specified distance from the package, using a two sided,
two layer board. This board is described in JESD 51-9.
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15
LTM4622
Applications Information
A graphical representation of the aforementioned thermal resistances is given in Figure 7; blue resistances are
contained within the μModule regulator, whereas green
resistances are external to the µModule.
As a practical matter, it should be clear to the reader that
no individual or sub-group of the four thermal resistance
parameters defined by JESD 51-12 or provided in the
Pin Configuration section replicates or conveys normal
operating conditions of a μModule. For example, in normal
board-mounted applications, never does 100% of the
device’s total power loss (heat) thermally conduct exclusively through the top or exclusively through bottom of the
µModule—as the standard defines for θJCtop and θJCbottom,
respectively. In practice, power loss is thermally dissipated
in both directions away from the package—granted, in the
absence of a heat sink and airflow, a majority of the heat
flow is into the board.
Within a SIP (system-in-package) module, be aware there
are multiple power devices and components dissipating
power, with a consequence that the thermal resistances
relative to different junctions of components or die are not
exactly linear with respect to total package power loss. To
reconcile this complication without sacrificing modeling
simplicity—but also, not ignoring practical realities—an
approach has been taken using FEA software modeling
2.0
2.0
12VIN
5VIN
1.8
1.6
1.4
POWER LOSS (W)
POWER LOSS (W)
1.6
1.2
1.0
0.8
0.6
1.2
1.0
0.8
0.6
0.4
0.2
0.2
0
1
4
3
2
OUTPUT CURRENT (A)
5
4622 F08
Figure 8. 1V Output Power Loss
0
12VIN
5VIN
2.0
1.4
0.4
0
2.5
12VIN
5VIN
POWER LOSS (W)
1.8
along with laboratory testing in a controlled-environment
chamber to reasonably define and correlate the thermal
resistance values supplied in this data sheet: (1) Initially,
FEA software is used to accurately build the mechanical
geometry of the µModule and the specified PCB with all of
the correct material coefficients along with accurate power
loss source definitions; (2) this model simulates a softwaredefined JEDEC environment consistent with JSED51-12
to predict power loss heat flow and temperature readings
at different interfaces that enable the calculation of the
JEDEC-defined thermal resistance values; (3) the model
and FEA software is used to evaluate the µModule with
heat sink and airflow; (4) having solved for and analyzed
these thermal resistance values and simulated various
operating conditions in the software model, a thorough
laboratory evaluation replicates the simulated conditions
with thermo-couples within a controlled-environment
chamber while operating the device at the same power
loss as that which was simulated. An outcome of this
process and due-diligence yields a set of derating curves
provided in other sections of this data sheet. After these
laboratory test have been performed and correlated to the
µModule model, then the θJB and θBA are summed together
to correlate quite well with the µModule model with no
airflow or heat sinking in a properly define chamber. This
θJB + θBA value is shown in the Pin Configuration section
1.5
1.0
0.5
0
1
4
3
2
OUTPUT CURRENT (A)
5
4622 F09
Figure 9. 1.5V Output Power Loss
0
0
1
4
3
2
OUTPUT CURRENT (A)
5
4622 F10
Figure 10. 2.5V Output Power Loss
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2.5
1.0
1.5
1.0
0.5
0
1.5
1.0
0
1
4
3
2
OUTPUT CURRENT (A)
0
5
4
3
2
0
1
4622 F11
4
3
2
OUTPUT CURRENT (A)
0
5
Figure 12. 5V Output Power Loss
5
5
0LFM
200LFM
400LFM
1
0
40
50
OUTPUT CURRENT (A)
5
4
3
2
0LFM
200LFM
400LFM
1
0
60 70 80 90 100 110 120
AMBIENT TEMPERATURE (˚C)
40
50
4622 F14
4
3
2
0
60 70 80 90 100 110 120
AMBIENT TEMPERATURE (˚C)
Figure 15. 5V to 1.5V Derating Curve,
No Heat Sink
5
5
0LFM
200LFM
400LFM
1
0
40
50
OUTPUT CURRENT (A)
5
OUTPUT CURRENT (A)
6
2
4
3
2
0LFM
200LFM
400LFM
1
60 70 80 90 100 110 120
AMBIENT TEMPERATURE (˚C)
4622 F17
Figure 17. 5V to 2.5V Derating Curve,
No Heat Sink
50
0
40
50
60 70 80 90 100 110 120
AMBIENT TEMPERATURE (˚C)
Figure 16. 12V to 1.5V Derating
Curve, No Heat Sink
6
3
40
4622 F16
6
4
0LFM
200LFM
400LFM
1
4622 F15
Figure 14. 12V to 1V Derating Curve,
No Heat Sink
60 70 80 90 100 110 120
AMBIENT TEMPERATURE (˚C)
Figure 13. 5V to 1V Derating Curve,
No Heat Sink
6
2
50
4622 F13
6
3
40
4622 F12
6
4
0LFM
200LFM
400LFM
1
0.5
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
5
1.0
Figure 11. 3.3V Output Power Loss
OUTPUT CURRENT (A)
6
VIN = 12V
2.5
POWER LOSS (W)
POWER LOSS (W)
3.0
12VIN
5VIN
OUTPUT CURRENT (A)
3.0
4
3
2
0LFM
200LFM
400LFM
1
60 70 80 90 100 110 120
AMBIENT TEMPERATURE (˚C)
4622 F18
Figure 18. 12V to 2.5V Derating Curve,
No Heat Sink
0
40
50
60 70 80 90 100 110 120
AMBIENT TEMPERATURE (˚C)
4622 F19
Figure 19. 5V to 3.3V Derating Curve,
No Heat Sink
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LTM4622
6
6
5
5
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
Applications Information
4
3
2
0LFM
200LFM
400LFM
1
0
40
50
4
3
2
0LFM
200LFM
400LFM
1
0
60 70 80 90 100 110 120
AMBIENT TEMPERATURE (˚C)
4622 F20
40
50
60 70 80 90 100 110 120
AMBIENT TEMPERATURE (˚C)
4622 F21
Figure 20. 12V to 3.3V Derating Curve,
No Heat Sink
Figure 21. 12V to 5V Derating Curve,
No Heat Sink
Table 2. 1V Output
DERATING CURVE
VIN (V)
POWER LOSS CURVE
AIR FLOW (LFM)
HEAT SINK
θJA(°C/W)
Figures 13, 14
5, 12
Figure 8
0
None
19 – 20
Figures 13, 14
5, 12
Figure 8
200
None
17 – 18
Figures 13, 14
5, 12
Figure 8
400
None
17 – 18
VIN (V)
POWER LOSS CURVE
AIR FLOW (LFM)
HEAT SINK
θJA(°C/W)
Table 3. 1.5V Output
DERATING CURVE
Figures 15, 16
5, 12
Figure 9
0
None
19 – 20
Figures 15, 16
5, 12
Figure 9
200
None
17 – 18
Figures 15, 16
5, 12
Figure 9
400
None
17 – 18
DERATING CURVE
VIN (V)
POWER LOSS CURVE
AIR FLOW (LFM)
HEAT SINK
θJA(°C/W)
Figures 17, 18
5, 12
Figure 10
0
None
19 – 20
Figures 17, 18
5, 12
Figure 10
200
None
17 – 18
Figures 17, 18
5, 12
Figure 10
400
None
17 – 18
DERATING CURVE
VIN (V)
POWER LOSS CURVE
AIR FLOW (LFM)
HEAT SINK
θJA(°C/W)
Figure 19, 20
5, 12
Figure 11
0
None
19 – 20
Figure 19, 20
5, 12
Figure 11
200
None
17 – 18
Figure 19, 20
5, 12
Figure 11
400
None
17 – 18
DERATING CURVE
VIN (V)
POWER LOSS CURVE
AIR FLOW (LFM)
HEAT SINK
θJA(°C/W)
Figure 21
12
Figure 12
0
None
19 – 20
Figure 21
12
Figure 12
200
None
17 – 18
Figure 21
12
Figure 12
400
None
17 – 18
Table 4. 2.5V Output
Table 5. 3.3V Output
Table 6. 5V Output
4622fc
18
For more information www.linear.com/LTM4622
LTM4622
Applications Information
Table 7. Output Voltage Response for Each Regulator Channel vs Component Matrix (Refer to Figure 24)
1.25A Load Step Typical Measured Values
CIN
(CERAMIC) PART NUMBER
COUT1
(CERAMIC) PART NUMBER
VALUE
COUT2
(BULK)
VALUE
Murata
GRM188R61E475KE11# 4.7µF, 25V, Murata
0603, X5R
GRM21R60J476ME15#
Murata
GRM188R61E106MA73# 10µF, 25V, Murata
0603, X5R
GRM188R60J226MEA0# 22µF, 6.3V,
0603, X5R
Taiyo Yuden TMK212BJ475KG-T
VOUT
(V)
4.7µF, 25V, Taiyo
0805, X5R Yuden
CIN
COUT1
(CERAMIC)
CIN
(CERAMIC)
(μF)
(μF)
(BULK)
47µF, 6.3V,
0805, X5R
JMK212BJ476MG-T
COUT2
(BULK)
(μF)
CFF
(pF)
DROOP
VIN (V) (mV)
PART NUMBER VALUE
Panasonic 6TPC150M
150µF, 6.3V 3.5
× 2.8 × 1.4mm
Sanyo
47µF, 6.3V,
0805, X5R
P-P
DERIVATION
(mV)
RECOVERY
TIME (μS)
LOAD
STEP (A)
LOAD STEP
SLEW RATE
(A/μS)
RFB
(kΩ)
1
10
0
1 x 47
0
0
5, 12
0
103
4
1.25
10
90.9
1
10
0
1 x 10
150
0
5, 12
0
52
10
1.25
10
90.9
1.2
10
0
1 x 47
0
0
5, 12
0
113
4
1.25
10
60.4
1.2
10
0
1 x 10
150
0
5, 12
0
56
10
1.25
10
60.4
1.5
10
0
1 x 47
0
0
5, 12
0
131
8
1.25
10
40.2
1.5
10
0
1 x 10
150
0
5, 12
0
61
14
1.25
10
40.2
1.8
10
0
1 x 47
0
0
5, 12
0
150
8
1.25
10
30.1
1.8
10
0
1 x 10
150
0
5, 12
0
67
16
1.25
10
30.1
2.5
10
0
1 x 47
0
0
5, 12
0
184
8
1.25
10
19.1
2.5
10
0
1 x 10
150
0
5, 12
0
78
20
1.25
10
19.1
3.3
10
0
1 x 47
0
0
5, 12
0
200
12
1.25
10
13.3
3.3
10
0
1 x 10
150
0
5, 12
0
78
35
1.25
10
13.3
5
10
0
1 x 47
0
0
5, 12
0
309
12
1.25
10
8.25
5
10
0
1 x 10
150
0
5, 12
0
114
60
1.25
10
8.25
4622fc
For more information www.linear.com/LTM4622
19
LTM4622
Applications Information
and should accurately equal the θJA value because approximately 100% of power loss flows from the junction
through the board into ambient with no airflow or top
mounted heat sink.
The 1V, 1.5V, 2.5V, 3.3V and 5V power loss curves in
Figures 8 to 12 can be used in coordination with the load
current derating curves in Figures 13 to 21 for calculating
an approximate θJA thermal resistance for the LTM4622 (in
two-phase single output operation) with no heat sinking and
various airflow conditions. The power loss curves are taken
at room temperature, and are increased with multiplicative
factors of 1.35 assuming junction temperature at 120°C.
The derating curves are plotted with the output current
starting at 5A and the ambient temperature at 40°C. These
output voltages are chosen to include the lower and higher
output voltage ranges for correlating the thermal resistance.
Thermal models are derived from several temperature
measurements in a controlled temperature chamber along
with thermal modeling analysis. The junction temperatures
are monitored while ambient temperature is increased
with and without airflow. The power loss increase with
ambient temperature change is factored into the derating
curves. The junctions are maintained at 120°C maximum
while lowering output current or power with increasing
ambient temperature. The decreased output current will
decrease the internal module loss as ambient temperature
is increased. The monitored junction temperature of 120°C
minus the ambient operating temperature specifies how
much module temperature rise can be allowed. As an
example in Figure 15 the load current is derated to ~3A
at ~102°C with no air or heat sink and the power loss for
the 5V to 1.5V at 3A output is about 0.95W. The 0.95W
loss is calculated with the ~0.7W room temperature loss
from the 5V to 1.5V power loss curve at 3A, and the 1.35
multiplying factor. If the 102°C ambient temperature is
subtracted from the 120°C junction temperature, then the
difference of 18°C divided by 0.95W equals a 19°C/W θJA
thermal resistance. Table 3 specifies a 19 – 20°C/W value
which is very close. Table 2 to 6 provide equivalent thermal
resistances for 1V, 1.5V, 2.5V, 3.3V and 5V outputs with
and without airflow. The derived thermal resistances in
Table 2 to 6 for the various conditions can be multiplied
by the calculated power loss as a function of ambient
temperature to derive temperature rise above ambient,
thus maximum junction temperature. Room temperature
power loss can be derived from the efficiency curves in
the Typical Performance Characteristics section and adjusted with the above ambient temperature multiplicative
factors. The printed circuit board is a 1.6mm thick four
layer board with two ounce copper for the two outer layers
and one ounce copper for the two inner layers. The PCB
dimensions are 95mm × 76mm.
Figure 22 shows a measured temperature picture of the
LTM4622 with no heatsink and no airflow, from 12V input
down to 3.3V and 5V output with 2.5A DC current on each.
4622 F22
Figure 22. Thermal Picture, 12V Input, 3.3V and 5V Output, 2.5A DC Each Output with No Air Flow and No Heat Sink
4622fc
20
For more information www.linear.com/LTM4622
LTM4622
Applications Information
Safety Considerations
The LTM4622 modules do not provide galvanic isolation
from VIN to VOUT. There is no internal fuse. If required,
a slow blow fuse with a rating twice the maximum input
current needs to be provided to protect each unit from
catastrophic failure. The device does support thermal
shutdown and over current protection.
Layout Checklist/Example
The high integration of LTM4622 makes the PCB board
layout very simple and easy. However, to optimize its
electrical and thermal performance, some layout considerations are still necessary.
Use large PCB copper areas for high current paths,
including VIN, GND, VOUT1 and VOUT2. It helps to
minimize the PCB conduction loss and thermal stress.
nn Place high frequency ceramic input and output
capacitors next to the VIN, PGND and VOUT pins to
minimize high frequency noise.
nn
Place a dedicated power ground layer underneath
the unit.
nn To minimize the via conduction loss and reduce
module thermal stress, use multiple vias for
interconnection between top layer and other
power layers.
nn Do not put via directly on the pad, unless they are
capped or plated over.
nn Use a separated SGND ground copper area for
components connected to signal pins. Connect the
SGND to GND underneath the unit.
nn For parallel modules, tie the V
OUT, VFB, and COMP
pins together. Use an internal layer to closely connect these pins together. The TRACK pin can be
tied a common capacitor for regulator soft-start.
nn Bring out test points on the signal pins for
monitoring.
Figure 23 gives a good example of the recommended layout.
nn
4622 F23
Figure 23. Recommended PCB Layout
4622fc
For more information www.linear.com/LTM4622
21
LTM4622
Applications Information
VIN
4V TO 20V
10µF
0.1µF
PGOOD1 PGOOD2
VOUT1
VIN
RUN1
RUN2 LTM4622 VOUT2
INTVCC
COMP1
SYNC/MODE
COMP2
TRACK/SS1
FB1
TRACK/SS2
FREQ
10µF
10µF
VOUT1
1V, 2.5A
VOUT2
1.8V, 2.5A
FB2
GND
30.1k
0.1µF
90.6k
4622 F24
Figure 24. 4VIN to 20VIN, 1V and 1.8V Output at 2.5A Design
PGOOD
VIN
4V TO 20V
10µF
PGOOD1 PGOOD2
VIN
VOUT1
RUN1
VOUT2
RUN2 LTM4622
COMP1
INTVCC
COMP2
SYNC/MODE
TRACK/SS1
0.1µF
TRACK/SS2
FREQ
VOUT
1.2V, 5A
22µF
FB1
FB2
30.2k
GND
4622 F25
Figure 25. 4VIN to 20VIN, 1.2V Two Phase in Parallel 5A Design
VIN
8V TO 20V
10µF
0.1µF
PGOOD1 PGOOD2
VOUT1
VIN
RUN1
RUN2 LTM4622 VOUT2
INTVCC
COMP1
SYNC/MODE
COMP2
TRACK/SS1
FB1
TRACK/SS2
FREQ
0.1µF
10µF
10µF
VOUT1
3.3V, 2.5A
VOUT2
5V, 2.5A
FB2
GND
8.25k
13.3k
324k
4622 F26
Figure 26. 8VIN to 20VIN, 3.3V and 5V Output at 2.5A with 2MHz Switching Frequency
4622fc
22
For more information www.linear.com/LTM4622
LTM4622
Applications Information
VIN
3.3V
PGOOD1 PGOOD2
VIN
VOUT1
RUN1
RUN2 LTM4622 VOUT2
INTVCC
COMP1
SYNC/MODE
COMP2
TRACK/SS1
FB1
10µF
VOUT1
0.1µF
TRACK/SS2
FREQ
60.4k
10µF
VOUT1
1.5V, 2.5A
VOUT2
1.2V, 2.5A
10µF
FB2
GND
60.4k
60.4k
40.2k
4622 F27
Figure 27. 3.3VIN, 1.5V and 1.2V Output at 2.5A Design with Output Coincident Tracking
PGOOD
VIN
4V TO 20V
22µF
33.2k
V+
INTVCC
1µF
LTC6902
SET
DIV
PGOOD1 PGOOD2
VIN
VOUT1
RUN1
VOUT2
RUN2 LTM4622
COMP1
INTVCC
COMP2
SYNC/MODE
TRACK/SS1
FB1
TRACK/SS2
FREQ
FB2
GND
47µF
VOUT
1V, 10A
COMP
FB
22.6k
MOD
PH
GND
OUT1
OUT4
OUT2
OUT3
PGOOD
PGOOD1 PGOOD2
VIN
VOUT1
RUN1
VOUT2
RUN2 LTM4622
COMP1
INTVCC
COMP2
SYNC/MODE
0.1µF
TRACK/SS1
FB1
TRACK/SS2
FREQ
FB2
COMP
FB
GND
4622 F28
Figure 28. 4 Phase, 1V Output at 10A Design with LTC6902
4622fc
For more information www.linear.com/LTM4622
23
LTM4622
Package Description
PACKAGE ROW AND COLUMN LABELING MAY VARY
AMONG µModule PRODUCTS. REVIEW EACH PACKAGE
LAYOUT CAREFULLY.
LTM4622 Component LGA and BGA Pinout
PIN ID
FUNCTION
PIN ID
FUNCTION
PIN ID
FUNCTION
PIN ID
FUNCTION
PIN ID
FUNCTION
A1
VOUT2
A2
VIN
A3
TRACK/SS2
A4
FB2
A5
COMP2
B1
VOUT2
B2
RUN2
B3
VIN
B4
PGOOD2
B5
GND
C1
GND
C2
GND
C3
INTVCC
C4
FREQ
C5
SYNC/MODE
D1
VOUT1
D2
RUN1
D3
VIN
D4
PGOOD1
D5
GND
E1
VOUT1
E2
VIN
E3
TRACK/SS1
E4
FB1
E5
COMP1
4622fc
24
For more information www.linear.com/LTM4622
0.000
For more information www.linear.com/LTM4622
2.540
1.270
0.3175
0.3175
1.270
2.540
SUGGESTED PCB LAYOUT
TOP VIEW
2.540
PACKAGE TOP VIEW
1.270
4
0.3175
0.000
0.3175
PIN “A1”
CORNER
E
1.270
aaa Z
2.540
Y
D
X
aaa Z
// bbb Z
SYMBOL
A
b
D
E
e
F
G
H1
H2
aaa
bbb
eee
H1
SUBSTRATE
0.27
1.45
MIN
1.72
0.60
NOM
1.82
0.63
6.25
6.25
1.27
5.08
5.08
0.32
1.50
DIMENSIONS
Ø eee S Z X Y
Z
0.37
1.55
0.15
0.10
0.15
MAX
1.92
0.66
TOTAL NUMBER OF LGA PADS: 25
DETAIL A
Øb (25 PLACES)
DETAIL B
H2
MOLD
CAP
NOTES
DETAIL B
A
b
F
3
e
SEE NOTES
4
3
2
1
PACKAGE BOTTOM VIEW
5
G
DETAIL A
E
D
C
B
A
PIN 1
7
SEE NOTES
DETAILS OF PAD #1 IDENTIFIER ARE OPTIONAL,
BUT MUST BE LOCATED WITHIN THE ZONE INDICATED.
THE PAD #1 IDENTIFIER MAY BE EITHER A MOLD OR
MARKED FEATURE
4
7
TRAY PIN 1
BEVEL
!
PACKAGE IN TRAY LOADING ORIENTATION
LTMXXXXXX
µModule
LGA 25 0613 REV Ø
PACKAGE ROW AND COLUMN LABELING MAY VARY
AMONG µModule PRODUCTS. REVIEW EACH PACKAGE
LAYOUT CAREFULLY
6. THE TOTAL NUMBER OF PADS: 25
5. PRIMARY DATUM -Z- IS SEATING PLANE
LAND DESIGNATION PER JESD MO-222, SPP-010
3
2. ALL DIMENSIONS ARE IN MILLIMETERS
NOTES:
1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994
COMPONENT
PIN “A1”
(Reference LTC DWG # 05-08-1949 Rev Ø)
LGA Package
25-Lead (6.25mm × 6.25mm × 1.82mm)
LTM4622
Package Description
Please refer to http://www.linear.com/product/LTM4622#packaging for the most recent package drawings.
4622fc
25
0.000
2.540
1.270
0.3175
0.3175
1.270
2.540
SUGGESTED PCB LAYOUT
TOP VIEW
2.540
PACKAGE TOP VIEW
1.270
4
0.3175
0.000
0.3175
PIN “A1”
CORNER
E
1.270
aaa Z
2.540
26
D
X
0.630 ±0.025
Y
aaa Z
// bbb Z
SYMBOL
A
A1
A2
b
b1
D
E
e
F
G
H1
H2
aaa
bbb
ccc
ddd
eee
For more information www.linear.com/LTM4622
0.27
1.45
MIN
2.22
0.50
1.72
0.60
0.60
NOM
2.42
0.60
1.82
0.75
0.63
6.25
6.25
1.27
5.08
5.08
0.32
1.50
DIMENSIONS
ddd M Z X Y
eee M Z
H1
SUBSTRATE
b1
A2
A
MAX
2.62
0.70
1.92
0.90
0.66
NOTES
DETAIL B
PACKAGE SIDE VIEW
0.37
1.55
0.15
0.10
0.20
0.30
0.15
TOTAL NUMBER OF BALLS: 25
DETAIL A
Øb (25 PLACES)
DETAIL B
H2
MOLD
CAP
ccc Z
A1
Z
(Reference LTC DWG # 05-08-1502 Rev Ø)
Z
b
F
3
e
SEE NOTES
5
4
3
2
1
PACKAGE BOTTOM VIEW
G
DETAIL A
E
D
C
B
A
PIN 1
7
SEE NOTES
DETAILS OF PIN #1 IDENTIFIER ARE OPTIONAL,
BUT MUST BE LOCATED WITHIN THE ZONE INDICATED.
THE PIN #1 IDENTIFIER MAY BE EITHER A MOLD OR
MARKED FEATURE
BALL DESIGNATION PER JESD MS-028 AND JEP95
7
TRAY PIN 1
BEVEL
!
PACKAGE IN TRAY LOADING ORIENTATION
LTMXXXXXX
µModule
BGA 25 0515 REV Ø
PACKAGE ROW AND COLUMN LABELING MAY VARY
AMONG µModule PRODUCTS. REVIEW EACH PACKAGE
LAYOUT CAREFULLY
6. SOLDER BALL COMPOSITION IS 96.5% Sn/3.0% Ag/0.5% Cu
5. PRIMARY DATUM -Z- IS SEATING PLANE
4
3
2. ALL DIMENSIONS ARE IN MILLIMETERS
NOTES:
1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994
COMPONENT
PIN “A1”
BGA Package
25-Lead (6.25mm × 6.25mm × 2.42mm)
LTM4622
Package Description
Please refer to http://www.linear.com/product/LTM4622#packaging for the most recent package drawings.
4622fc
LTM4622
Revision History
REV
DATE
DESCRIPTION
A
08/15
Added “Single 5A” to Title and Features
PAGE NUMBER
B
01/16
Added BGA package
C
11/16
Corrected equations of tracking start-up time from RTR(TOP)/[RTR(TOP) + RTR(BOT)] to RTR(BOT)/[RTR(TOP) + RTR(BOT)]
1
1, 2, 25, 26
13, 14
4622fc
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection
of its circuits
as described
herein will not infringe on existing patent rights.
For more
information
www.linear.com/LTM4622
27
LTM4622
Package Photo
Design Resources
SUBJECT
DESCRIPTION
µModule Design and Manufacturing Resources
Design:
• Selector Guides
• Demo Boards and Gerber Files
• Free Simulation Tools
µModule Regulator Products Search
1. Sort table of products by parameters and download the result as a spread sheet.
Manufacturing:
• Quick Start Guide
• PCB Design, Assembly and Manufacturing Guidelines
• Package and Board Level Reliability
2. Search using the Quick Power Search parametric table.
TechClip Videos
Quick videos detailing how to bench test electrical and thermal performance of µModule products.
Digital Power System Management
Linear Technology’s family of digital power supply management ICs are highly integrated solutions that
offer essential functions, including power supply monitoring, supervision, margining and sequencing,
and feature EEPROM for storing user configurations and fault logging.
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PART NUMBER
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DESCRIPTION
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14VIN, 4A Step-Down µModule Regulator
LTM4625
20VIN, 5A Step-Down µModule Regulator
LTM4619
Dual 26V, 4A Step-Down µModule Regulator
LTM4618
26VIN, 6A Step-Down µModule Regulator
LTM4614
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Dual 5V, 4A µModule Regulator
Multiphase Oscillator with Spread Spectrum
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LTM4642
LTM4631
LTM4643
COMMENTS
4V ≤ VIN ≤ 20V, 0.6V ≤ VOUT ≤ 5.5V, PLL Input, CLKOUT, VOUT Tracking, PGOOD,
6.25mm × 6.25mm × 1.82mm LGA
4V ≤ VIN ≤ 14V, 0.6V ≤ VOUT ≤ 5.5V, VOUT Tracking, PGOOD,
6.25mm × 6.25mm × 5.01mm BGA
4V ≤ VIN ≤ 20V, 0.6V ≤ VOUT ≤ 5.5V, PLL Input, CLKOUT, VOUT Tracking, PGOOD,
6.25mm × 6.25mm × 5.01mm BGA
4.5V ≤ VIN ≤ 26.5V, 0.8V ≤ VOUT ≤ 5V, PLL Input, VOUT Tracking, PGOOD,
15mm × 15mm × 2.82mm LGA
4.5V ≤ VIN ≤ 26.5V, 0.8V ≤ VOUT ≤ 5V, PLL Input, VOUT Tracking,
9mm × 15mm × 4.32mm LGA
2.375V ≤ VIN ≤ 5.5V, 0.8V ≤ VOUT ≤ 5V, 15mm × 15mm × 2.82mm LGA
4.5V ≤ VIN ≤ 20V, 0.6V ≤ VOUT ≤ 5.5V, 9mm × 11.25mm × 4.92mm BGA
4.5V ≤ VIN ≤ 15V, 0.6V ≤ VOUT ≤ 1.8V, 16mm × 16mm × 1.91mm LGA
4V ≤ VIN ≤ 20V, 0.6V ≤ VOUT ≤ 3.3V, 9mm × 15mm × 1.82mm LGA
4622fc
28
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
For more information www.linear.com/LTM4622
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com/LTM4622
LT 1116 REV C • PRINTED IN USA
 LINEAR TECHNOLOGY CORPORATION 2015
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