Linear Technology Analog Devices LTM4622A Datasheet

Dual Ultrathin 2A or Single 4A

LOAD CURRENT (A)

0

0.2

0.4

0.6

0.811.2

1.4

1.6

1.8

2.0

707580859095100

EFFICIENCY (%)

4622A TA01b

V

OUT

= 5V

V

OUT

= 3.3V

8V TO 20V

OUT2

5V, 2A

Step-Down DC/DC µModule Regulator

FEATURES DESCRIPTION

LTM4622A

n

Complete Solution in <1cm

n

Wide Input Voltage Range: 3.6V to 20V

n

1.5V to 12V Output Voltage

n

Dual 2A (3A Peak) or Single 4A Output Current

n

±1.5% Maximum Total Output Voltage Regulation

2

Error Over Load, Line and Temperature

n

Current Mode Control, Fast Transient Response

n

External Frequency Synchronization

n

Multiphase Parallelable with Current Sharing

n

Output Voltage Tracking and Soft-Start Capability

n

Selectable Burst Mode® Operation

n

Overvoltage Input and Overtemperature Protection

n

Power Good Indicators

n

6.25mm × 6.25mm × 1.82mm LGA and

6.25mm × 6.25mm × 2.42mm BGA Packages

APPLICATIONS

n

General Purpose Point-of-Load Conversion

n

Telecom, Networking and Industrial Equipment

n

Medical Diagnostic Equipment

n

Test and Debug Systems

All registered trademarks and trademarks are the property of their respective owners.

The LT M®4622A is a complete dual 2A step-down switching

®

mode µModule

(micromodule) regulator in a tiny ultrathin

6.25mm × 6.25mm × 1.82mm LGA and 2.42mm BGA pack­ages. Included in the package are the switching controller,
power FET

s, inductor and support components. Operating
over an input voltage range of 3.6V to 20V, the LTM4622A
supports an output voltage range of 1.5V to 12V, set by a
single external resistor. Its high efficiency design delivers
dual 2A continuous, 3A peak, output current. Only a few
ceramic input and output capacitors are needed.

The LTM4622A 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.

Fault protection features include input overvoltage, output
overcurrent and overtemperature protection.

The LTM4622A is available with SnPb (BGA) or RoHS
compliant terminal finish.

Product Selection Guide

PART NUMBER VIN RANGE V

LTM4622

LTM4622A 1.5V to 12V Dual 2A or Single 4A

3.6V to 20V

RANGE I

OUT

0.6V to 5.5V Dual 2.5A or Single 5A

OUT

TYPICAL APPLICATION

3.3V and 5V Dual Output DC/DC Step-Down µModule Regulator

PGOOD1 PGOOD2

V

V

IN

4.7µF
25V

IN1

V

IN2

RUN1

RUN2

INTV

CC

SYNC/MODE

TRACK/SS1

TRACK/SS2

FREQ

LTM4622A

GND

V

OUT1

V

OUT2

COMP1

COMP2

FB1

FB2

4622A TA01a

For more information www.analog.comDocument Feedback

8.25k

47µF

47µF

V

OUT1

3.3V, 2A

V

13.3k

12V Input, 3.3V and 5V Output,

Efficiency vs Load Current

Rev B

1

LTM4622A

25-LEAD (6.25mm × 6.25mm × 2.42mm)

TOP VIEW

TRACK/SS1

TRACK/SS2

ABSOLUTE MAXIMUM RATINGS

V

, V

IN1

V

OUT

PGOOD1, PGOOD2 ..................................... –0.3V to 18V

RUN1, RUN2 .................................... –0.3V to V

INTV
SYNC/MODE, COMP1, COMP2,

FB1,

PIN CONFIGURATION

................................................... –0.3V to 22V

IN2

........................................................... –0.3V to 16V

+ 0.3V

IN

, TRACK/SS1, TRACK/SS2 ............ –0.3V to 3.6V

CC

FB2 ........................................... –0.3V to INTV

(See Pin Functions, Pin Configuration Table)

TOP VIEW

COMP2

5

PGOOD2

FB2

4

INTV

CC

TRACK/SS2

3

V

IN2

RUN2

2

V

IN2

1

V

OUT2

25-LEAD (6.25mm × 6.25mm × 1.82mm)

T

= 125°C, θ

JMAX

θ

JB

SYNC/

MODE

A

B C D E

LGA PACKAGE

= 17°C/W, θ

JCtop

+ θBA = 22°C/W, θJA = 22°C/W,

WEIGHT = 0.21g

COMP1GND GND

JCbottom

FREQ
PGOOD1
FB1
V

TRACK/SS1
RUN1

V
GND
V

IN1

IN1

OUT1

= 11°C/ W,

CC

(Note 1)

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

SYNC/
MODE

A

B C D E

BGA PACKAGE

= 17°C/W, θ

JCtop

+ θBA = 22°C/W, θJA = 22°C/W,

WEIGHT = 0.25g

COMP1GND GND

JCbottom

FREQ
PGOOD1
FB1
V

IN1

RUN1
V

IN1

GND
V

OUT1

= 11°C/ W,

PGOOD2

FB2

INTV

V

RUN2

V

V

OUT2

T

JMAX

COMP2

5

4

CC

3

IN2

2

IN2

1

= 125°C, θ

θ

JB

ORDER INFORMATION

PART NUMBER PAD OR BALL FINISH

LT M4622AEV#PBF Au (RoHS) LT M4622AV e4 LGA 4 –40°C to 125°C
LT M4622AIV#PBF Au (RoHS) LT M4622AV e4 LGA 4 –40°C to 125°C
LT M4622AEY#PBF SAC305 (RoHS) LT M4622AY e1 BGA 4 –40°C to 125°C
LT M4622AIY#PBF SAC305 (RoHS) LT M4622AY e1 BGA 4 –40°C to 125°C
LT M4622AIY SnPb (63/37) LT M4622AY e0 BGA 4 –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.

• Pb-free and Non-Pb-free Part Markings:

www.linear.com/leadfree

2

http://www.linear.com/product/LTM4622A#orderinfo

PART MARKING*

•

Recommended LGA and BGA PCB Assembly and Manufacturing

Procedures:

www.linear.com/umodule/pcbassembly

•

LGA and BGA Package and Tray Drawings:

www.linear.com/packaging

For more information www.analog.com

PACKAGE

TYPE

RATING

MSL

TEMPERATURE RANGE
(Note 2)DEVICE FINISH CODE

Rev B

LTM4622A

ELECTRICAL CHARACTERISTICS

The l denotes the specifications which apply over the specified internal
operating temperature range (Note 2). Specified as each individual output channel at TA = 25°C, V
noted per the typical application shown in Figure27.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Switching Regulator Section: per Channel

V

IN1

V

IN2

V

OUT(RANGE)

V

OUT(DC)

V

RUN

I

Q(VIN)

I

S(VIN)

I

OUT(DC)

ΔV

OUT(Line)/VOUT

ΔV

OUT(Load)/VOUT

V

OUT(AC)

ΔV

OUT(START)

t

START

ΔV

OUTLS

t

SETTLE

I

OUTPK

V

FB

I

FB

R

FBHI

I

TRACK/SS

t

SS

t

ON(MIN)

t

OFF(MIN)

V

PGOOD

R

PGOOD

V

INTVCC

Input DC Voltage Range

Input DC Voltage Range 3.6V < V

Output Voltage Range V

Output Voltage, Total Variation
with Line and Load

IN1 = VIN2

CIN = 22µF, C
MODE = INT

< 20V

IN1

= 3.6V to 20V

= 100µF Ceramic, RFB = 40.2k,

OUT

VCC,V

IN1 = VIN2

= 3.6V to 20V, I

= 0A to 2A

OUT

RUN Pin On Threshold RUN Threshold Rising

RUN Threshold Falling

Input Supply Bias Current V

IN1 = VIN2

V

IN1 = VIN2

= 12V, V
= 12V, V

= 1.5V, MODE = GND

OUT

= 1.5V, MODE = INTVCC

OUT

Shutdown, RUN1 = RUN2 = 0

Input Supply Current V

Output Continuous Current Range V

Line Regulation Accuracy V

Load Regulation Accuracy V

Output Ripple Voltage I

Turn-On Overshoot I

Turn-On Time C

IN1 = VIN2

IN1 = VIN2

OUT

OUT

OUT

V

OUT

OUT

V

OUT

OUT

V

IN1 = VIN2

Peak Deviation for Dynamic Load Load: 0% to 50% to 0% of Full Load, C

Ceramic, V

Settling Time for Dynamic Load
Step

Output Current Limit V

Voltage at FB Pin I

Load: 0% to 50% to 0% of Full Load, C
Ceramic, V

IN1 = VIN2

OUT

= 12V, V

= 12V, V

= 1.5V, V

= 1.5V, I

= 0A, C

OUT

OUT

= 1.5V, I

OUT

OUT

IN1 = VIN2

= 1.5V (Note 3)

OUT

= 3.6V to 20V, I

= 0A to 2A

= 100µF Ceramic, V

= 2A 0.32 A

= 0A

OUT

IN1 = VIN2

= 12V,

= 1.5V

= 0A, C

= 100µF Ceramic, V

OUT

IN1 = VIN2

= 12V,

= 1.5V

= 100µF Ceramic, No Load, TRACK/SS = 0.01µF,

= 0A, V

= 12V, V

IN1 = VIN2

IN1 = VIN2

= 12V, V

OUT

= 1.5V

OUT

= 100µF

= 12V, V

= 12V, V

OUT

OUT

OUT

= 1.5V 3 4 A

= 1.5V

= 1.5V

OUT

= 100µF

OUT

= 1.5V

Current at FB Pin (Note 4) ±30 nA

Resistor Between V

and FB Pins 60.00 60.40 60.80 kΩ

OUT

Track Pin Soft-Start Pull-Up Current TRACK/SS = 0V 1.25 µA

Internal Soft-Start Time 10% to 90% Rise Time (Note 4) 400 700 μs

Minimum On-Time (Note 4) 20 ns

Minimum Off-Time (Note 4) 45 ns

PGOOD Trip Level VFB With Respect to Set Output

V

Ramping Negative

FB

V

Ramping Positive

FB

PGOOD Pull-Down Resistance 1mA Load 20 Ω

Internal VCC Voltage V

IN1 = VIN2

= 3.6V to 20V 3.1 3.3 3.5 V

= V

IN1

l

l

l

l

= 12V, unless otherwise

IN2

3.6 20 V

1.5 20 V

1.5 12 V

1.477 1.50 1.523 V

1.20

0.97

1.27

1.00

1.35

1.03

7

500

45

l

0 2 A

l

l

0.01 0.1 %/V

0.2 1.0 %

5 mV

30 mV

1.25 ms

100 mV

20 µs

l

0.592 0.60 0.608 V

–8

–14

8

14

mA

µA
µA

V
V

%
%

For more information www.analog.com

Rev B

3

LTM4622A

ELECTRICAL CHARACTERISTICS

The l denotes the specifications which apply over the specified internal
operating temperature range (Note 2). Specified as each individual output channel at TA = 25°C, V
noted per the typical application shown in Figure27.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Load Reg INTVCC Load Regulation ICC = 0mA to 50mA 1.3 %

V

INTVCC

f

OSC

f

SYNC

I

MODE

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 LTM4622A is tested under pulsed load conditions such that
T

≈ TA. The LTM4622AE is guaranteed to meet performance

J

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 LTM4622AI 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.

Oscillator Frequency 1 MHz

Frequency Sync Range With Respect to Set Frequency ±30 %

MODE Input Current MODE = INTV

CC

Note 3: See output current derating curves for different V
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.

IN1

= V

= 12V, unless otherwise

IN2

–1.5 µA

, V

and TA.

IN

OUT

4

Rev B

For more information www.analog.com

TYPICAL PERFORMANCE CHARACTERISTICS

LOAD CURRENT (A)

0

0.2

0.4

0.6

0.811.2

1.4

1.6

1.8

2.0

60

65

70

75

80

85

90

95

100

EFFICIENCY (%)

4622A G01

3.3V OUTPUT, 1MHz

1.5V OUTPUT, 1MHz

LOAD CURRENT (A)

0

0.2

0.4

0.6

0.811.2

1.4

1.6

1.8

2.0

60

65

70

75

80

85

90

95

100

EFFICIENCY (%)

4622A G02

8V OUTPUT, 1.5MHz

5V OUTPUT, 1.5MHz

3.3V OUTPUT, 1MHz

1.5V OUTPUT, 1MHz

LOAD CURRENT (A)

0

0.2

0.4

0.6

0.811.2

1.4

1.6

1.8

2.0

60

65

70

75

80

85

90

95

100

EFFICIENCY (%)

4622A G03

3.3V OUTPUT, 1MHz

1.5V OUTPUT, 1MHz

12V OUTPUT, 1.5MHz

8V OUTPUT, 1.5MHz

5V OUTPUT, 1.5MHz

LOAD CURRENT (mA)

0.001

0.01

0.1110010

2030405060708090100

EFFICIENCY (%)

4622A G04

Burst Mode OPERATION

CMM

AC-COUPLED

LOAD-STEP = 1A TO 2A (10A/μs)

AC-COUPLED

4622A G06

LOAD-STEP = 1A TO 2A (10A/μs)

AC-COUPLED

LOAD-STEP = 1A TO 2A (10A/μs)

AC-COUPLED

LOAD-STEP = 1A TO 2A (10A/μs)

AC-COUPLED

4622A G09

LOAD-STEP = 1A TO 2A (10A/μs)

LTM4622A

Efficiency vs Load Current
at 5V

IN

Burst Mode Efficiency,
12VIN, 1.5V

OUT

Efficiency vs Load Current
at 12V

IN

1.5V Output Transient Response

LOAD STEP

1A/DIV

Efficiency vs Load Current
at 16V

IN

3.3V Output Transient Response

LOAD STEP

1A/DIV

LOAD STEP

1A/DIV

V

OUT

100mV/DIV

5V Output Transient Response

50µs/DIV

VIN = 12V, V
OUTPUT CAPACITOR = 47µF ×2 CERAMIC
10pF FEED-FORWARD CAPACITOR

= 5V, fSW = 1MHz

OUT

4622A G07

V

OUT

50mV/DIV

LOAD STEP

1A/DIV

V

OUT

100mV/DIV

50µs/DIV

VIN = 12V, V
OUTPUT CAPACITOR = 47µF ×1 CERAMIC
10pF FEED-FORWARD CAPACITOR

= 1.5V, fSW = 1MHz

OUT

8V Output Transient Response

50µs/DIV

VIN = 12V, V
OUTPUT CAPACITOR = 47µF ×2 CERAMIC
10pF FEED-FORWARD CAPACITOR

= 8V, fSW = 1.5MHz

OUT

4622A G05

4622A G08

V

OUT

50mV/DIV

LOAD STEP

1A/DIV

V

OUT

100mV/DIV

50µs/DIV

VIN = 12V, V
OUTPUT CAPACITOR = 47µF ×1 CERAMIC
10pF FEED-FORWARD CAPACITOR

= 3.3V, fSW = 1MHz

OUT

12V Output Transient Response

50µs/DIV

VIN = 16V, V
OUTPUT CAPACITOR = 47µF ×2 CERAMIC
10pF FEED-FORWARD CAPACITOR

= 12V, fSW = 1.5MHz

OUT

For more information www.analog.com

Rev B

5

LTM4622A

0.5A/DIV

4622A G11

SOFT-START CAP = 0.1µF

4622A G14

1A/DIV

2V/DIV

OUTPUT CAPACITOR = 10µF + 47µF POSCAP

10V/DIV

4622A G10

SOFT-START CAP = 0.1µF

4622A G12

2V/DIV

1A/DIV

+ 47µF POSCAP

4622A G13

2V/DIV

1A/DIV

OUTPUT CAPACITOR = 10µF + 47µF POSCAP

AC-COUPLED

OUTPUT CAPACITOR = 10µF + 47µF POSCAP

TYPICAL PERFORMANCE CHARACTERISTICS

Start-Up with No Load
CurrentApplied

V

OUT

2V/DIV

RUN

I

IN

1A/DIV

10ms/DIV

VIN = 12V, V
OUTPUT CAPACITOR = 10µF CERAMIC
+ 47µF POSCAP

= 3.3V, fSW = 1MHz

OUT

Short-Circuit with 2A Load
Current Applied

V

OUT

Start-Up with 2A Load
CurrentApplied

V

OUT

2V/DIV

RUN

10V/DIV

I

IN

10ms/DIV

VIN = 12V, V
OUTPUT CAPACITOR = 10µF CERAMIC
+ 47µF POSCAP

= 3.3V, fSW = 1MHz

OUT

Recover from Short-Circuit with
No Load Current Applied

V

OUT

V

OUT

V

OUT

10mV/DIV

Short-Circuit with No Load
Current Applied

I

IN

20µs/DIV

VIN = 12V, V
OUTPUT CAPACITOR = 10µF CERAMIC

= 3.3V, fSW = 1MHz

OUT

Steady-State Output Voltage Ripple

I

IN

VIN = 12V, V

20µs/DIV

= 3.3V, fSW = 1MHz

OUT

I

IN

VIN = 12V, V

20µs/DIV

= 3.3V, fSW = 1MHz

OUT

VIN = 12V, V

20µs/DIV

= 3.3V, fSW = 1MHz

OUT

4622A G15

6

Rev B

For more information www.analog.com

PIN FUNCTIONS

LTM4622A

PACKAGE ROW AND COLUMN LABELING MAY VARY
AMONG µModule PRODUCTS. REVIEW EACH PACKAGE
LAYOUT CAREFULLY.

V

(D3, E2), V

IN1

(A2, B3): Power Input Pins. Apply

IN2

input voltage between these pins and GND pins. Rec­ommend placing input decoupling capacitance directly
between BOTH V

IN1

and V

pins and GND pins. Please

IN2

note the module internal control circuity is running off

. Channel 2 will not work without a voltage higher that

V

IN1

3.6V presents at V

IN1

.

GND (C1 to C2, B5, D5): Power Ground Pins for Both
Input and Output Returns.

INTV

(C3): Internal 3.3V Regulator Output. The internal

CC

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 Synchroni

­zation Input. Tie this pin to ground to force continuous
synchronous operation at all output loads. Floating this pin
or tying it to INTV

enables high efficiency BurstMode

CC

operation at light loads. Drive this pin with a clock to syn­chronize the LTM4622A switching frequency. An internal
phase-locked loop will for

ce 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.

V

OUT1

(D1, E1), V

(A1, B1): Power Output Pins of

OUT2

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 INTV

to reduce

CC

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 ampli

­fier, 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 INTV

on this pin,

CC

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 V

with a 60.4k preci-

OUT

sion resistor. Different output voltages can be programmed

an additional resistor between FB and GND pins. In

with
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 Switch

­ing 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.

For more information www.analog.com

Rev B

7

LTM4622A

8V TO 20V

4622A BD

BLOCK DIAGRAM

13.3k

8.25k

0.1µF

0.1µF

FB1

FB2

INTV

CC

SYNC/MODE

TRACK/SS1

TRACK/SS2

RUN1

RUN2

COMP1

COMP2

INTERNAL

COMP

INTERNAL

COMP

2.2µF

V

OUT1

60.4k

POWER CONTROL

V

OUT2

60.4k

2.2µH

2.2µH

0.22µF

0.1µF

0.22µF

0.1µF

PGOOD1

PGOOD2

V

IN1

V

OUT1

GND

V

IN2

V

OUT2

GND

10k

10k

10µF

47µF

10µF

47µF

INTV

INTV

V

OUT1

3.3V
2A

V

OUT2

5V
2A

CC

CC

V

IN

FREQ

324k

Figure1. Simplified LTM4622A Block Diagram

DECOUPLING REQUIREMENTS

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

C

IN

C

OUT

External Input Capacitor Requirement
(V

= 3.6V to 20V, V

IN

OUT

= 1.5V)

External Output Capacitor Requirement
(V

= 3.6V to 20V, V

IN

OUT

= 1.5V)

= 2A 4.7 10 µF

I

OUT

= 2A 22 47 µF

I

OUT

8

Rev B

For more information www.analog.com

OPERATION

LTM4622A

The LTM4622A is a dual output standalone non-isolated
switch mode DC/DC power supply. It can deliver two 2A
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 1.5V to 12V over 3.6V to 20V input
voltage range. The typical application schematic is shown
in Figure27.

The LTM4622A contains an integrated controlled on-time
valley current mode regulator, power MOSFETs, inductors,
and other supporting discrete components. The default
switching frequency is 1MHz. For output voltages above

3.3V, an external resistor is required between FREQ and
GND pins to set the operating frequency to 1.5MHz to
2MHz 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
compensation, the LTM4622A 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 cur

­rent 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 protec

­tion been utilized by shutting down both power MOSFETs
when V

rises above 22.5V to protect internal devices.

IN

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 set
ting MODE pin to INTV

. The TRACK/SS pin is used for

CC

-

power supply tracking and soft-start programming. See
the Applications Information section.

APPLICATIONS INFORMATION

The typical LTM4622A application circuit is shown in
Figure 27. External component selection is primarily
determined by the input voltage, the output voltage and
the maximum load current. Refer to Table7 for specific
external capacitor requirements for a particular application.

to V

V

IN

There are restrictions in the maximum V
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:

DC

Step-Down Ratios

OUT

= 1 – t

(MAX)

OFF(MIN)

• f

SW

and V

IN

step

OUT

For more information www.analog.com

where t

OFF(MIN)

LTM4622A, and f

is the minimum off-time, 45ns typical for

is the switching frequency. Conversely

SW

the minimum on-time limit imposes a minimum duty cycle
of the converter which can be calculated as:

DC

(MIN)

where t

= t

ON(MIN)

ON(MIN)

• f

SW

is the minimum on-time, 20ns typical for
LTM4622A. 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.

Rev B

9