Rev. F 01/09

3

TOP252-262

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Section List

Functional Block Diagram ....................................................................................................................................... 4

Pin Functional Description ...................................................................................................................................... 6

TOPSwitch-HX Family Functional Description ....................................................................................................... 7

CONTROL (C) Pin Operation .................................................................................................................................... 8

Oscillator and Switching Frequency.......................................................................................................................... 8

Pulse Width Modulator ............................................................................................................................................ 9

Maximum Load Cycle .............................................................................................................................................. 9

Error Amplifier .......................................................................................................................................................... 9

On-Chip Current Limit with External Programmability ............................................................................................... 9

Line Under-Voltage Detection (UV).......................................................................................................................... 10

Line Overvoltage Shutdown (OV)............................................................................................................................ 11

Hysteretic or Latching Output Overvoltage Protection (OVP)................................................................................... 11

Line Feed-Forward with DC

Remote ON/OFF and Synchronization.................................................................................................................... 13

Soft-Start ............................................................................................................................................................... 13

Shutdown/Auto-Restart ......................................................................................................................................... 13

Hysteretic Over-Temperature Protection ................................................................................................................. 13

Bandgap Reference ............................................................................................................................................... 13

High-Voltage Bias Current Source .......................................................................................................................... 13

Typical Uses of FREQUENCY (F) Pin ...................................................................................................................... 15

Typical Uses of VOLTAGE MONITOR (V) and EXTERNAL CURRENT LIMIT (X) Pins .......................................... 16

Typical Uses of MULTI-FUNCTION (M) Pin ........................................................................................................... 18

Application Examples .............................................................................................................................................. 21

A High Efficiency, 35 W, Dual Output – Universal Input Power Supply..................................................................... 21

A High Efficiency, 150 W, 250-380 VDC Input Power Supply............................................

...................................... 22

A High Efficiency, 20 W Continuous – 80 W Peak, Universal Input Power Supply ................................................... 23

A High Efficiency, 65 W, Universal Input Power Supply ........................................................................................... 24

Key Application Considerations .............................................................................................................................. 25

TOPSwitch-HX vs.TOPSwitch-GX

....................................................................................................................... . 25

TOPSwitch-HX Design Considerations .................................................................................................................. 26

TOPSwitch-HX Layout Considerations ................................................................................................................... 27

Quick Design Checklist .......................................................................................................................................... 31

Design Tools .......................................................................................................................................................... 31

Product Specifications and Test Conditions .......................................................................................................... 32

Typical Performance Characteristics .................................................................................................................... 39

Package Outlines .................................................................................................................................................... 43

Part Ordering Information ........................................................................................................................................ 47