LTC3725EMSE 查看數據表（PDF） - Linear Technology

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LTC3725EMSE

Single-Switch Forward Controller and Gate Driver

Linear Technology 

FEATURES

■ High Speed Gate Driver for Forward Converter

■ On-Chip Rectifier and Self-Starting Architecture

Eliminates Need for Separate Gate Drive Bias

Supply

■ Wide Input Voltage Supply Range: 9V and Up

■ Linear Regulator Controller for Fast Start-Up

■ Precision UVLO with Adjustable Hysteresis

■ Overcurrent Protection

■ Volt-Second Limit Prevents Transformer Core

Saturation

■ Voltage Feedforward for Fast Transient Response

■ Available in 10-Lead MSOP Package

U

APPLICATIO S

■ Isolated 48V Telecommunication Systems

■ Internet Servers and Routers

■ Distributed Power Step-Down Converters

■ Automotive and Heavy Equipment

LTC3725

Single-Switch Forward

Controller and Gate Driver

DESCRIPTIO

The LTC®3725 is a controller for a single-switch forward

converter and includes an on-chip gate driver.

For secondary-side control, combine the LTC3725 with

the LTC3706 PolyPhase® secondary-side synchronous

forward controller to create a complete forward converter

using a minimum of discrete parts. A proprietary scheme

is used to multiplex gate drive signals across the isolation

barrier through a tiny pulse transformer. The on-chip

rectifier and the same pulse transformer provide gate drive

bias power.

Alternatively, the LTC3725 can be used as a standalone

voltage mode controller in a primary-side control architec-

ture with optoisolator feedback. Voltage feedforward pro-

vides excellent line regulation and transient response.

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

a registered trademark of Linear Technology Corporation. All other trademarks are the

property of their respective owners. Patent Pending

TYPICAL APPLICATIO

VIN+

36V TO 72V

1µF

100V

×2

VIN–

36V-72V to 3.3V/30A Isolated Single-Switch Forward Converter

T1

•

•

L1

0.85µH

Si7450DP

0.030Ω

1W

•

2.2nF

200V

HAT2165

×2

0.0012Ω

1W

HAT2165

×2

B0540W

1.2Ω

1/4W

100µF

6.3V

×2

10µF

365k

15k

100k

FDC2512

NDRV GATE IS

VCC

FB/IN+

UVLO LTC3725

1µF

SSFLT

FS/IN–

VSLMT PGND GND

33nF

0.1µF

T2

••

5.1k

162k

L1: PULSE PA1294.910

T1: PULSE PA0815

T2: PULSE PA0297

FCX491A

2.2µF

1µF

FG SW IS–

IS+

PT+

SG VIN NDRV VCC MODE

LTC3706

FB

PT–

GND PGND RUN/SS SLP REGSD FS/SYNC PHASE ITH

33nF

100k

470pF

3.3k

47nF

VOUT+

3.3V

30A

+

220µF

6.3V

VOUT–

2.74k

604Ω

3725 TA01

3725f

1

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