LT3957A View Datasheet(PDF) - Linear Technology

Part Name

Description

Manufacturer

LT3957A

Boost, Flyback, SEPIC and Inverting Converter with 5A, 40V Switch

Linear Technology 

LT3957A

BLOCK DIAGRAM

VIN

R4 R3

L1

CIN

EN/UVLO

25

VIN

27

1.72V – A11

+

– A12

–0.88V +

1.6V +

A1

–

+

A2

–0.8V –

A10

IS1

2μA

1.22V

2.5V

IS2

10μA

INTERNAL

REGULATOR

AND UVLO

UVLO

Q3

A8

2.5V

G4

2.7V

IS3

TLO

165˚C

G6

VC –

+A7

G5

CURRENT

LIMIT

5.2V LDO

M2

DRIVER

SR1

RO

G2

S

Q2

PWM

COMPARATOR

1.28V –

+A3

SLOPE

VISENSE

RAMP

RAMP

GENERATOR

G1

100kHz-1MHz

OSCILLATOR

48mV

A6

SENSE

A5

CDC

D1

SW

8, 9, 20,

21, 38

L2

t

VOUT

COUT

INTVCC

28

CVCC

M1

RSENSE

SENSE1

6

GND

12, 13, 14,

15, 16, 17

SENSE2

3

FREQUENCY

FOLDBACK

LOW SIDE

CLAMP

1.2V +

+ A4

Q1

–

FREQ

PROG

VOUT

FBX

31

R2

R1

VC

SS

30

32

CC2

RC

CSS

CC1

SYNC

34

RT

33

RT

4, 23,

24, 37

SGND

3957A F01

Figure 1. LT3957A Block Diagram Working as a SEPIC Converter

3957afa

8

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