LINEAR TECHNOLOGY LTM4602 Technical data

LTM4602

6A High Effi ciency

DC/DC µModule

FEATURES

n

Complete Switch Mode Power Supply

n

Wide Input Voltage Range: 4.5V to 20V

n

6A DC, 8A Peak Output Current

n

0.6V to 5V Output Voltage

n

1.5% Output Voltage Regulation

n

Ultrafast Transient Response

n

Current Mode Control

n

Pb-Free (e4) RoHS Compliant Package with Gold-

Pad Finish

n

Pin Compatible with the LTM4600

n

Up to 92% Effi ciency

n

Programmable Soft-Start

n

Output Overvoltage Protection

n

Optional Short-Circuit Shutdown Timer

n

See the LTM4602HV for Operation Up to 28VIN

n

Small Footprint, Low Profi le (15mm × 15mm ×

2.8mm) Surface Mount LGA Package

APPLICATIONS

n

Telecom and Networking Equipment

n

Servers

n

Industrial Equipment

n

Point of Load Regulation

DESCRIPTION

The LTM®4602 is a complete 6A DC/DC step down power
supply. Included in the package are the switching control­ler, power FETs, inductor, and all support components.
Operating over an input voltage range of 4.5V to 20V, the
LTM4602 supports an output voltage range of 0.6V to 5V,
set by a single resistor. This high effi ciency design delivers
6A continuous current (8A peak), needing no heat sinks or
airfl ow to meet power specifi cations. Only bulk input and
output capacitors are needed to fi nish the design.

The low profi le package (2.8mm) enables utilization of
unused space on the bottom of PC boards for high density
point of load regulation. High switching frequency and an
adaptive on-time current mode architecture enables a very
fast transient response to line and load changes without
sacrifi cing stability. Fault protection features include
integrated overvoltage and short circuit protection with
a defeatable shutdown timer. A built-in soft-start timer is
adjustable with a small capacitor.

The LTM4602 is packaged in a thermally enhanced, compact
(15mm × 15mm) and low profi le (2.8mm) over-molded
Land Grid Array (LGA) package suitable for automated as­sembly by standard surface mount equipment. For the 4.5V
to 28V input range version, refer to the LTM4602HV.

L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
μModule is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners. Protected by U.S. Patents including 5481178, 6100678, 6580258,
5847554, 6304066.

TYPICAL APPLICATION

6A μModuleTM Power Supply with 4.5V to 20V Input

V

4.5V TO 20V

IN

V

C

IN

V

IN

LTM4602

V

OSET

PGND SGND

OUT

C

OUT

R

SET

66.5k

4602 TA01a

V

OUT

1.5V
6A

Effi ciency vs Load Current

with 12V

100

90

80

70

60

50

40

EFFICIENCY (%)

30

20

10

0

0

*950kHz INSTEAD OF 1.3MHz
INCREASES 3.3V EFFICIENCY 2%

2

LOAD CURRENT (A)

(FCB = 0)

IN

0.8V

1.2V

1.5V

1.8V

2.5V

3.3V

3.3V

4

OUT
OUT
OUT
OUT
OUT
OUT
OUT

6

(950kHz)*

8

4602 TA01b

4602fa

1

LTM4602

(

)

(Note 1)

FCB, EXTVCC, PGOOD, RUN/SS, V

, SVIN, f

V

IN

, COMP ............................................. –0.3V to 2.7V

V

OSET

............................................ –0.3V to 20V

ADJ

Operating Temperature Range (Note 2).... –40°C to 85°C

Junction Temperature ........................................... 125°C

Storage Temperature Range ................... –55°C to 125°C

.......... –0.3V to 6V

OUT

PIN CONFIGURATION ABSOLUTE MAXIMUM RATINGS

TOP VIEW

IN

ADJ

f

V

IN

PGND

V

OUT

LGA PACKAGE

104-LEAD

T

JMAX

DERIVED FROM 95mm × 76mm PCB WITH 4 LAYERS

θ

JA

15mm × 15mm × 2.8mm

= 125°C, θJA = 15°C/W, θJC = 6°C/W,

WEIGHT = 1.7g

OSET

EXTVCCV

SV

COMP
SGND
RUN/SS
FCB

PGOOD

ORDER INFORMATION

LEAD FREE FINISH PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LTM4602EV#PBF LTM4602V 104-Lead (15mm × 15mm × 2.8mm) LGA –40°C to 85°C

LTM4602IV#PBF LTM4602V 104-Lead (15mm × 15mm × 2.8mm) LGA –40°C to 85°C

Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based fi nish parts.

For more information on lead free part marking, go to: http://www.linear.com/leadfree/
This product is only offered in trays. For more information go to: http://www.linear.com/packaging/

The

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifi cations are at TA = 25°C, VIN = 12V. External CIN = 120μF, C
application (front page) confi guration.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

IN(DC)

V

OUT(DC)

Input Specifi cations

V

IN(UVLO)

I

INRUSH(VIN)

I

Q(VIN)

Input DC Voltage

Output Voltage FCB = 0V

Under Voltage Lockout Threshold I

Input Inrush Current at Startup I

Input Supply Bias Current I

l denotes the specifi cations which apply over the –40°C to 85°C

= 200μF/Ceramic per typical

OUT

l

4.5 20 V

V

= 5V or 12V, V

IN

= 0A 3.4 4 V

OUT

= 0A. V

OUT

V

IN

V

IN

= 0A, EXTVCC Open

OUT

V

IN

V

IN

V

IN

V

IN

OUT

= 5V
= 12V

= 12V, V
= 12V, V
= 5V, V
= 5V, V

= 1.5V, FCB = 0

OUT

OUT
OUT
OUT

Shutdown, RUN = 0.8V, V

= 1.5V, I

OUT

= 1.5V, FCB = 5V

= 1.5V, FCB = 0V
= 1.5V, FCB = 5V
= 1.5V, FCB = 0V

= 12V

IN

OUT

= 0A

1.478

l

1.470

1.50

1.50

1.522

1.530

0.6

0.7

1.2
42

1.0
52
50 100

mA
mA
mA
mA

μA

V

A
A

2

4602fa

LTM4602

ELECTRICAL CHARACTERISTICS

The l denotes the specifi cations which apply over the –40°C to 85°C
temperature range, otherwise specifi cations are at T

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

I

S(VIN)

Output Specifi cations

I

OUTDC

ΔV

OUT(LINE)

V

OUT

ΔV

OUT(LOAD)

V

OUT

V

OUT(AC)

fs Output Ripple Voltage Frequency V

t

START

ΔV

OUTLS

t

SETTLE

I

OUTPK

Control Stage

V

OSET

V

RUN/SS

I

RUN(C)/SS

I

RUN(D)/SS

– SV

V

IN

IN

I

EXTVCC

R

FBHI

V

FCB

I

FCB

PGOOD Output

ΔV

OSETH

ΔV

OSETL

ΔV

OSET(HYS)

V

PGL

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.

Input Supply Current VIN = 12V, V

Output Continuous Current Range
(See Output Current Derating Curves for
Different V

, V

and TA)

IN

OUT

Line Regulation Accuracy V

Load Regulation Accuracy V

Output Ripple Voltage VIN = 12V, V

Turn-On Time V

Voltage Drop for Dynamic Load Step V

Settling Time for Dynamic Load Step Load: 10% to 50% to 10% of Full Load 25 μs

Output Current Limit Output Voltage in Foldback

Voltage at V

Pin I

OSET

RUN ON/OFF Threshold 0.8 1.5 2 V

Soft-Start Charging Current V

Soft-Start Discharging Current V

Current into EXTVCC Pin EXTVCC = 5V, FCB = 0V, V

Resistor Between V

OUT

and V

OSET

Forced Continuous Threshold 0.57 0.6 0.63 V

Forced Continuous Pin Current V

PGOOD Upper Threshold V

PGOOD Lower Threshold V

PGOOD Hysteresis V

PGOOD Low Voltage I

= 25°C, VIN = 12V. Per typical application (front page) confi guration.

A

= 1.5V, I

V

IN

V

IN

V

IN

OUT

V

IN

OUT

V

IN

OUT

OUT

V
V

OUT

C

OUT

OUT

= 12V, V
= 5V, V

= 12V, V

= 1.5V, I

= 3.3V, I

OUT

= 1.5V, I

OUT

= 1.5V 0 6 A

OUT

= 0A, FCB = 0V,

OUT

= 4.5V to 20V

= 1.5V, I

= 0A to 6A, FCB = 0V,

OUT

= 5V, VIN = 12V (Note 3)

= 1.5V, I

OUT

= 1.5V, I

= 1.5V, I

= 12V

IN

= 5V

IN

= 6A, FCB = 0V 850 kHz

OUT

= 1A

OUT

= 1.5V, Load Step: 0A/μs to 3A/μs
= 22μF 6.3V, 330μF 4V POSCAP,

= 6A

OUT

= 6A

OUT

= 6 A

OUT

l

l

= 0A, FCB = 0V 10 15 mV

OUT

0.88

1.80

2.08

0.15 0.3 %

±0.25
±0.15

±0.5
±1.0

0.5

0.7

30 mV

P-P

ms
ms

See Table 2

V

= 12V, V

IN

V

= 5V, V

IN

= 0A, V

OUT

= 0V –0.5 –1.2 –3 μA

RUN/SS

= 4V 0.8 1.8 3 μA

RUN/SS

OUT

OUT

= 1.5V

OUT

= 1.5V

= 1.5V

9
9

l

0.591 0.6 0.609 V

EXTVCC = 0V, FCB = 0V 100 mV

I

OUT

= 0A

OUT

= 1.5V,

16 mA

Pins 100 kΩ

= 0.6V –1 –2 μA

FCB

Rising 7.5 10 12.5 %

OSET

Falling –7.5 –10 –12.5 %

OSET

Returning 2 %

OSET

= 5mA 0.15 0.4 V

PGOOD

Note 2: The LTM4602E is guaranteed to meet performance specifi cations
from 0°C to 85°C. Specifi cations over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. The LTM4602I is guaranteed over the
–40°C to 85°C temperature range.

Note 3: Test assumes current derating versus temperature.

4602fa

A
A
A

%
%

A
A

3

LTM4602

w

)

p

Light Load Effi ci

TYPICAL PERFORMANCE CHARACTERISTICS

Effi ciency vs Load Current

ith 5V

100

90

80

70

60

EFFICIENCY (%)

50

40

30

0

(FCB = 0)

IN

*FOR 5V TO 3.3V CONVERSION,
SEE FREQUENCY ADJUSTMENT
IN APPLICATIONS INFORMATION

2

LOAD CURRENT (A)

ency vs
Load Current with 12V
(FCB > 0.7V, <5V)

100

0.8V

OUT

1.2V

OUT

1.5V

OUT

1.8V

OUT

2.5V

OUT

3.3V

*

OUT

4

6

8

4602 G01

IN

Effi ciency vs Load Current
with 12V(FCB = 0

100

90

80

70

60

EFFICIENCY (%)

50

40

30

0

*950kHz INSTEAD OF 1.3MHz
INCREASES 3.3V EFFICIENCY 2%

2

LOAD CURRENT (A)

0.8V

OUT

1.2V

OUT

1.5V

OUT

1.8V

OUT

2.5V

OUT

3.3V

OUT

3.3V

OUT

4

1.2V Transient Response 1.5V Transient Response

(See Figure 21 for all curves)

Effi ciency vs Load Current
with 20V

100

90

80

70

60

EFFICIENCY (%)

50

(950kHz)*

6

8

4602 G02

40

30

0

(FCB = 0)

IN

2

4

LOAD CURRENT (A)

1.2V

OUT

1.5V

OUT

1.8V

OUT

2.5V

OUT

3.3V

OUT

6

8

4602 G03

90

80

70

60

EFFICIENCY (%)

50

40

30

0

1.8V Transient Res

V

OUT

50mV/DIV

I

OUT

2A/DIV

1.8V AT 3A/μs LOAD STEP
C
330μF, 4V SANYO POSCAP

0.20.1

0.40.3

0.5

LOAD CURRENT (A)

20μs/DIV

= 1 × 22μF, 6.3V CERAMICS

OUT

V

OUT

50mV/DIV

I

OUT

2A/DIV

1.5V AT 3A/μs LOAD STEP
= 1 × 22μF, 6.3V CERAMICS

C

OUT

330μF, 4V SANYO POSCAP

20μs/DIV

1.2V

1.5V

1.8V

2.5V

3.3V

0.6 0.7 0.9

0.8

OUT
OUT
OUT
OUT
OUT

4602 G04

1

V

OUT

50mV/DIV

I

OUT

2A/DIV

1.2V AT 3A/μs LOAD STEP
C

= 1 × 22μF, 6.3V CERAMICS

OUT

330μF, 4V SANYO POSCAP

20μs/DIV

4602 G05

onse 2.5V Transient Response 3.3V Transient Response

4602 G07

V

OUT

50mV/DIV

I

OUT

2A/DIV

2.5V AT 3A/μs LOAD STEP
= 1 × 22μF, 6.3V CERAMICS

C

OUT

330μF, 4V SANYO POSCAP

20μs/DIV

4602 G08

V

OUT

50mV/DIV

I

OUT

2A/DIV

3.3V AT 3A/μs LOAD STEP
= 1 × 22μF, 6.3V CERAMICS

C

OUT

330μF, 4V SANYO POSCAP

20μs/DIV

4602 G06

4602 G09

4

4602fa

LTM4602

(

)

TYPICAL PERFORMANCE CHARACTERISTICS

Start-Up, No Load, I

V

OUT

0.5V/DIV

I

IN

0.5A/DIV

VIN = 12V

= 1.5V

V

OUT

C

= 1 × 22μF, 6.3V X5R

OUT

330μF, 4V SANYO POSCAP
NO EXTERNAL SOFT-START CAPACITOR

V

OUT

0.5V/DIV

I

0.5A/DIV

= 0A

OUT

200μs/DIV

4602 G10

Short-Circuit Protection,
I

= 6A

IN

VIN = 12V

= 1.5V

V

OUT

= 1 × 22μF, 6.3V X5R

C

OUT

330μF, 4V SANYO POSCAP
NO EXTERNAL SOFT-START CAPACITOR

20μs/DIV

Start-Up, I

Resistive Load

V

OUT

0.5V/DIV

I

IN

0.5A/DIV

VIN = 12V

= 1.5V

V

OUT

= 1 × 22μF, 6.3V X5R

C

OUT

330μF, 4V SANYO POSCAP
NO EXTERNAL SOFT-START CAPACITOR

4602 G13

OUT

= 6A

500μs/DIV

(V)

OUT

V

5.5

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

0

(See Figure 21 for all curves)

Short-Circuit Protection,

= 0A

I

V

OUT

0.5V/DIV

I

IN

0.5A/DIV

4602 G11

VIN to V

f

ADJ

SEE FREQUENCY ADJUSTMENT DISCUSSION
FOR 12VIN TO 5V
CONVERSION

Step-Down Ratio

OUT

= OPEN

0.6V

515

OUT

VIN = 12V

= 1.5V

V

OUT

= 1 × 22μF, 6.3V X5R

C

OUT

330μF, 4V SANYO POSCAP
NO EXTERNAL SOFT-START CAPACITOR

5V

3.3V

2.5V

1.8V

1.5V

1.2V

10 20

VIN (V)

AND 5VIN TO 3.3V

OUT

4602 G14

20μs/DIV

4602 G12

4602fa

5

LTM4602

PIN FUNCTIONS

(See Package Description for Pin Assignment)

VIN (Bank 1): Power Input Pins. Apply input voltage be-

tween these pins and PGND pins. Recommend placing
input decoupling capacitance directly between VIN pins
and PGND pins.

f

(Pin A15): A 110k resistor from VIN to this pin sets

ADJ

the one-shot timer current, thereby setting the switching
frequency. The LTM4602 switching frequency is typically
850kHz. An external resistor to ground can be selected to
reduce the one-shot timer current, thus lower the switching
frequency to accommodate a higher duty cycle step down
requirement. See the applications section.

SVIN (Pin A17): Supply Pin for Internal PWM Controller. Leave
this pin open or add additional decoupling capacitance.

EXTVCC (Pin A19): External 5V supply pin for controller. If
left open or grounded, the internal 5V linear regulator will
power the controller and MOSFET drivers. For high input
voltage applications, connecting this pin to an external
5V will reduce the power loss in the power module. The
EXTVCC voltage should never be higher than VIN.

V

(Pin A21): The Negative Input of The Error Amplifi er.

OSET

Internally, this pin is connected to V

with a 100k precision

OUT

resistor. Different output voltages can be programmed with
additional resistors between the V

and SGND pins.

OSET

COMP (Pin B23): Current Control Threshold and Error
Amplifi er Compensation Point. The current comparator
threshold increases with this control voltage. The voltage
ranges from 0V to 2.4V with 0.8V corresponding to zero
sense voltage (zero current).

TOP VIEW

2

1

V

8

IN

BANK 1

PGND

BANK 2

12

25

32

39

40

50

51

62

61

13 14 15

26 27 28 29 30 31

33 34 35 36 37 38

42 43 44 45 46 47

41

52 53 54 55 56 57 58

63 64 65 66 67 68 69

SGND (Pin D23): Signal Ground Pin. All small-signal
components should connect to this ground, which in turn
connects to PGND at one point.

RUN/SS (Pin F23): Run and Soft-Start Control. Forcing
this pin below 0.8V will shut down the power supply.
Inside the power module, there is a 1000pF capacitor
which provides approximately 0.7ms soft-start time with
200μF output capacitance. Additional soft-start time can
be achieved by adding additional capacitance between the
RUN/SS and SGND pins. The internal short-circuit latchoff
can be disabled by adding a resistor between this pin and
the VIN pin. This pullup resistor must supply a minimum
5μA pull up current.

FCB (Pin G23): Forced Continuous Input. Grounding this
pin enables forced continuous mode operation regardless
of load conditions. Tying this pin above 0.63V enables
discontinuous conduction mode to achieve high effi ciency
operation at light loads. There is an internal 4.75k resistor
between the FCB and SGND pins.

PGOOD (Pin J23): Output Voltage Power Good Indicator.
When the output voltage is within 10% of the nominal
voltage, the PGOOD is open drain output. Otherwise, this
pin is pulled to ground.

PGND (Bank 2): Power ground pins for both input and
output returns.

V

(Bank 3): Power Output Pins. Apply output load

OUT

between these pins and PGND pins. Recommend placing
High Frequency output decoupling capacitance directly
between these pins and PGND pins.

IN

ADJ

f

11109

OSET

EXTVCCV

SV

1918171676543

A

20

B

COMP

C

21

D

SGND

E

22

F

RUN/SS

23

G

FCB

H

24

J

PGOOD

48

59

70

K

49

L

60

M

71

N

6

73

74 75 76 77 78 79 80

72

V

OUT

BANK 3

84 85 86 87 88 89 90 91

83

94

95 96 97 98

35

1 23

24

79

68

99 100 101 102 103

11 13

10 12

14 16

15 17

81

92

19 21

18 20 22

82

P

93

R

104

T

4602 PN01

4602fa

SIMPLIFIED BLOCK DIAGRAM

RUN/SS

LTM4602

SV

IN

R

SET

66.5k

PGOOD

COMP

FCB

f

ADJ

SGND

EXTV

V

OSET

1000pF

1.5μF

Q1

INT

COMP

4.75k

10Ω

CC

CONTROLLER

Q2

15μF

6.3V

PGND

100k

0.5%

4602 F01

C

IN

C

OUT

V

IN

4.5V TO 20V

V

OUT

1.5V
6A MAX

Figure 1. Simplifi ed LTM4602 Block Diagram

DECOUPLING REQUIREMENTS

T

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

C

IN

C

OUT

External Input Capacitor Requirement
(V

= 4.5V to 20V, V

IN

OUT

= 1.5V)

External Output Capacitor Requirement
(V

= 4.5V to 20V, V

IN

OUT

= 1.5V)

= 25°C, VIN = 12V. Use Figure 1 confi guration.

A

= 6A 20 μF

I

OUT

= 6A, Refer to Table 2 in the

I

OUT

100 200 μF

Applications Information Section

4602fa

7

LTM4602

OPERATION

μModule Description

The LTM4602 is a standalone nonisolated synchronous
switching DC/DC power supply. It can deliver up to 6A of
DC output current with only bulk external input and output
capacitors. This module provides a precisely regulated
output voltage programmable via one external resistor from

0.6V
The input voltage range is 4.5V to 20V. A simplifi ed block
diagram is shown in Figure 1 and the typical application
schematic is shown in Figure 21.

The LTM4602 contains an integrated LTC constant on-time
current-mode regulator, ultralow R
switching speed and integrated Schottky diode. The typical
switching frequency is 850kHz at full load. With current
mode control and internal feedback loop compensation,
the LTM4602 module has suffi cient stability margins and
good transient performance under a wide range of operat­ing conditions and with a wide range of output capacitors,
even all ceramic output capacitors (X5R or X7R).

Current mode control provides cycle-by-cycle fast current
limit. In addition, foldback current limiting is provided in
an overcurrent condition while V
LTM4602 has defeatable short-circuit latch off. Internal
overvoltage and undervoltage comparators pull the open­drain PGOOD output low if the output feedback voltage exits
a ±10% window around the regulation point. Furthermore,

to 5.0VDC, not to exceed 80% of the input voltage.

DC

FETs with fast

DS(ON)

drops. Also, the

OSET

in an overvoltage condition, internal top FET Q1 is turned
off and bottom FET Q2 is turned on and held on until the
overvoltage condition clears.

Pulling the RUN/SS pin low forces the controller into its
shutdown state, turning off both Q1 and Q2. Releasing the
pin allows an internal 1.2μA current source to charge up
the soft-start capacitor. When this voltage reaches 1.5V,
the controller turns on and begins switching.

At low load current the module works in continuous cur­rent mode by default to achieve minimum output voltage
ripple. It can be programmed to operate in discontinuous
current mode for improved light load effi ciency when the
FCB pin is pulled up above 0.8V and no higher than 6V.
The FCB pin has a 4.75k resistor to ground, so a resistor

can set the voltage on the FCB pin.

to V

IN

When EXTV
linear regulator powers the controller and MOSFET gate
drivers. If a minimum 4.7V external bias supply is ap­plied on the EXTV
off, and an internal switch connects EXTV
driver voltage. This eliminates the linear regulator power
loss with high input voltage, reducing the thermal stress
on the controller. The maximum voltage on EXTV
6V. The EXTV

voltage. Also EXTVCC must be sequenced after VIN.

V

IN

pin is grounded or open, an integrated 5V

CC

pin, the internal regulator is turned

CC

to the gate

CC

pin is

CC

voltage should never be higher than the

CC

8

4602fa