LT1950

1

sn1950 1950fs

s

Wide Input Range: 3V to 25V

s

Programmable Volt-Second Clamp

s

Output Power Levels from 25W to 500W

s

Auxiliary Boost Converter Provides 10V Gate Drive

s

Programmable Operating Frequency (100kHz to

500kHz) with One External Resistor

s

Programmable Slope Compensation

s

Programmable Leading Edge Blanking

s

±2% Internal 1.23V Reference

s

Accurate Shutdown Pin Threshold with

Programmable Hysteresis

s

60ns Current Sense Delay

s

2.5V Auxiliary Reference Output

s

s

Current Mode Control

s

Small 16-Pin SSOP Package

s

Telecom Power Supplies

s

Automotive Power Supplies

s

Portable Electronic Equipment

s

Isolated and Nonisolated DC/DC Converters

Single Switch PWM

Controller with Auxiliary

Boost Converter

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

SLOPE

BOOST

BLANK

SYNC

GND

FB

SHDN

GATE

PGND

COMP

LT1950

1950 TA01a

0.1

µF

249k

4.99k

4.7k

0.022

µF

1

µF

470k

18k

100k

MBRB20200

47

µH

47

µF

26V

5A

0.015

Ω

Si7450

2.5V

Efficiency vs Load Current

LOAD CURRENT (A)

0.5

95

90

85

80

75

70

4.5

1950 TA01b

1.5

2.5

3.5

5.5

36V to 72V DC to 26V/5A (Single Switch) Forward Converter

The LT

and SEPIC controller that drives an N-channel power

MOSFET with few external components required.

A resistor programmable duty cycle clamp can be used to

generate a volt-second clamp for forward converter appli-

cations. An internal boost switcher is available for creating

a separate supply for the output gate driver, allowing 10V

gate drive from input voltages as low as 3V. The LT1950’s

operating frequency can be set with an external resistor

over a 100kHz to 500kHz range and a SYNC pin allows the

part to be synchronized to an external clock. Additional

programmability exists for leading edge blanking and

slope compensation.

A fast current sense comparator achieves 60ns current

sense delay and the error amplifier is a true voltage mode

error amplifier, allowing a wide range of compensation

networks. An accurate shutdown pin with programmable

hysteresis is available for undervoltage lockout and shut-

down. The LT1950 is available in a small 16-Pin SSOP

package.

APPLICATIO S

FEATURES

DESCRIPTIO

TYPICAL APPLICATIO