LTC3722-2_15 Datasheet, PDF(10/28 Page) Linear Technology – Synchronous Dual Mode Phase Modulated Full Bridge Controllers

English

English German Russian Spanish Italian Polish Chinese Japanese Korean French Portuguese	Language :

LTC3722-2_15 Datasheet, PDF (10/28 Pages) Linear Technology – Synchronous Dual Mode Phase Modulated Full Bridge Controllers

◁

LTC3722-1/LTC3722-2

TIMING DIAGRAM

PASSIVE LEG

DELAY

OUTA

OUTB

OUTC

ACTIVE LEG

DELAY

OUTD

RAMP

COMP

OUTE

OUTF

SYNC TURN OFF

DELAY (PROGRAMMABLE)

SYNC TURN OFF

DELAY (PROGRAMMABLE)

NOTE: SHADED AREAS CORRESPOND TO POWER DELIVERY PULSES.

372212 TD01

OPERATION

Phase-Shift Full Bridge PWM

Conventional full bridge switching power supply topologies

are often employed for high power, isolated DC/DC and

off-line converters. Although they require two additional

switching elements, substantially greater power and higher

efficiency can be attained for a given transformer size

compared to the more common single-ended forward and

flyback converters. These improvements are realized since

the full bridge converter delivers power during both parts

of the switching cycle, reducing transformer core loss

and lowering voltage and current stresses. The full bridge

converter also provides inherent automatic transformer

flux reset and balancing due to its bidirectional drive

configuration. As a result, the maximum duty cycle range

is extended, further improving efficiency. Soft-switching

variations on the full bridge topology have been proposed

to improve and extend its performance and application.

These zero voltage switching (ZVS) techniques exploit the

generally undesirable parasitic elements present within the

power stage. The parasitic elements are utilized to drive

near lossless switching transitions for all of the external

power MOSFETs.

LTC3722-1/LTC3722-2 phase-shift PWM controllers pro-

vide enhanced performance and simplify the design task

required for a ZVS phase-shifted full bridge converter.

The primary attributes of the LTC3722-1/LTC3722-2 as

compared to currently available solutions include:

1. Truly adaptive and accurate (DirectSenseTM technology)

ZVS with programmable timeout.

Benefit: higher efficiency, higher duty cycle capability,

eliminates external trim.

2. Fixed ZVS capability.

Benefit: enables secondary-side control and simplifies

external circuit.

372212fb

For more information www.linear.com/LTC3722

▷