LT3844IFE-TRPBF(RevB) Просмотр технического описания (PDF) - Linear Technology

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производитель

LT3844IFE-TRPBF
(Rev.:RevB)

High Voltage, Current Mode Switching Regulator Controller with Programmable Operating Frequency

Linear Technology 

LT3844

PIN FUNCTIONS

BOOST (Pin 16): The BOOST pin is the supply for the

bootstrapped gate drive and is externally connected to a

low ESR ceramic boost capacitor referenced to SW pin.

The recommended value of the BOOST capacitor, CBOOST,

is 50 times greater than the total input capacitance of the

topside MOSFET. In most applications 0.1μF is adequate.

The maximum voltage that this pin sees is VIN + VCC,

ground referred.

Exposed Pad (Pin 17): SGND. The exposed leadframe is

internally connected to the SGND pin. Solder the exposed

pad to the PCB ground for electrical contact and optimal

thermal performance.

FUNCTIONAL DIAGRAM

VIN

VIN

1

CIN

RA

SHDN

2

RB

BURST_EN

4

VFB

5

R1 R2

CC2

RC

CC1

VC

6

3

CSS

VIN

UVLO

(<4V)

8V

REGULATOR

3.8V

REGULATOR

VCC

UVLO

(<6V)

INTERNAL

SUPPLY RAIL

VREF

–+

FEEDBACK

REFERENCE

1.231V

BST

UVLO

BOOSTED SWITCH

DRIVER

BOOST

16

CBOOST

DRIVE

CONTROL

NOL

SWITCH

LOGIC

DRIVE

CONTROL

DRIVER

TG

15

SW

14

VCC

13

D2

CVCC

PGND

12

– gm +

ERROR

AMP

0.5V

100mV

CSS CLAMPED TO

VFB + VBE

~1V SOFT-START

BURST DISABLE

VREF + 200mV

2μA

50μA

FAULT CONDITION:

VIN UVLO

VCC UVLO

VSHDN UVLO

QS

R

CURRENT

SENSE

COMPARATOR

OSCILLATOR

SLOPE COMP

GENERATOR

SYNC

7

fSET

8

RSET

Burst Mode

OPERATION

–+

SGND

9

SENSE+

11

SENSE–

10

M1

L1 RSENSE

D1

VOUT

COUT

D3

(OPTIONAL)

3844 FD

3844fb

7

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