LTC3901

1

3901f

■

Programmable Timeout

Sequence Monitor

■

Undervoltage Lockout

Secondary Side

Synchronous Driver for Push-Pull

and Full-Bridge Converters

The LTC

driver designed to be used in isolated push-pull and full-

bridge converter power supplies. The chip drives two

external N-channel MOSFETs and accepts a transformer-

generated bipolar input to maintain sychronization with

the primary side controller.

The LTC3901 provides a full range of protection features

for the external MOSFETs. A programmable timeout func-

tion is included that disables both drivers when the syn-

chronization signal is missing or incorrect. Additionally,

the chip senses the output inductor current through the

drain-source resistance of the two MOSFETs, turning off

the MOSFETs if the inductor current reverses. The LTC3901

also shuts off the drivers if the supply is low or if the

synchronization sequence is incorrect.

Figure 1. Simplified Isolated Push-Pull Converter

LTC3723

PUSH-PULL

CONTROLLER

LT4430 OR LT1431

OPTOCOUPLER

DRIVER

DRVA

DRVB

SDRB

SDRA

ISOLATION

BARRIER

T1

L1

CSE+

ME

CSE–

CSF+

MF

CSF–

GND

PGND

LTC3901

OUT

T2

MA

MB

ME

MF

COMP

12V

36V TO 72V

3901 F01

+

FB

SYNC

TIMER

■

Isolated Telecom Power Supplies

DESCRIPTIO

FEATURES

APPLICATIO S

TYPICAL APPLICATIO

, LTC and LT are registered trademarks of Linear Technology Corporation.

All other trademarks are the property of their respective owners.