July 1996

Product Highlights

Low Cost Replacement for Discrete Switchers

• 20 to 50 fewer components - cuts cost, increases reliability

• Source-connected tab and Controlled MOSFET turn-on

reduce EMI and EMI filter costs

• Allows for a 50% smaller and lighter solution

• Cost competitive with linears above 5 W

Up to 90% Efficiency in Flyback Topology

• Built-in start-up and current limit reduce DC losses

• Low capacitance 350 V MOSFET cuts AC losses

• CMOS controller/gate driver consumes only 6 mW

• 70% maximum duty cycle minimizes conduction losses

Simplifies Design - Reduces Time to Market

• Supported by many reference designs

• Integrated PWM Controller and 350 V MOSFET in a

industry standard three pin TO-220 package

• Only one external capacitor needed for compensation,

bypass and start-up/auto-restart functions

System Level Fault Protection Features

• Auto-restart and cycle by cycle current limiting functions

handle both primary and secondary faults

• On-chip latching thermal shutdown protects the entire

system against overload

Highly Versatile

• Implements Buck, Boost, Flyback or Forward topology

• Easily interfaces with both opto and primary feedback

• Supports continuous or discontinuous mode of operation

• Specified for operation down to 16 V DC input

Description

The TOPSwitch family implements, with only three pins, all

functions necessary for an off-line switched mode control

system: high voltage N-channel power MOSFET with controlled

turn-on gate driver, voltage mode PWM controller with

integrated 100 kHz oscillator, high voltage start-up bias circuit,

bandgap derived reference, bias shunt regulator/error amplifier

for loop compensation and fault protection circuitry. Compared

to discrete MOSFET and controller or self oscillating (RCC)

switching converter solutions, a TOPSwitch integrated circuit

can reduce total cost, component count, size, weight and at the

same time increase efficiency and system reliability. These

®

PI-1704112995

AC

IN

DRAIN

SOURCE

CONTROL

TOPSwitch

Figure 1. Typical Application.

TOP100-4

TOPSwitch

Family

Three-terminal Off-line PWM Switch

ORDER

PART

NUMBER

OUTPUT POWER RANGE

TOPSwitch SELECTION GUIDE

FLYBACK

TOP100YAI*

0-20 W

0-30 W

TOP101YAI*

15-35 W

25-50 W

TOP102YAI*

20-45 W

35-70 W

TOP103YAI*

25-55 W

45-90 W

TOP104YAI*

30-60 W

55-110 W

®

* Package Outline: Y03A

devices are intended for 100/110 VAC off-line Power Supply

applications in the 0 to 60 W range and power factor correction

(PFC) applications in the 0 to 110 W range. They are also well

suited for Telecom, Cablecom and other DC to DC converter

applications in the 0-25 W range (see Design Note DN-16).

100/110 V

VAC

0-6.8 W

6-12 W

8.5-17 W

11-22 W

12-25 W

PFC/

BOOST

100/110

VAC

48 V

DC