TOP242-250
Section List
Functional Block Diagram ....................................................................................................................................... 3
Pin Functional Description ...................................................................................................................................... 4
TOPSwitch-GX Family Functional Description ....................................................................................................... 5
CONTROL (C) Pin Operation.................................................................................................................................. 6
Oscillator and Switching Frequency........................................................................................................................ 6
Pulse Width Modulator and Maximum Duty Cycle.................................................................................................. 7
Light Load Frequency Reduction............................................................................................................................ 7
Error Amplifier ......................................................................................................................................................... 7
On-Chip Current Limit with External Programmability ............................................................................................ 7
Line Under-Voltage Detection (UV)......................................................................................................................... 8
Line Overvoltage Shutdown (OV) ........................................................................................................................... 8
Line Feed-Forward with DCMAX Reduction .............................................................................................................. 8
Remote ON/OFF and Synchronization ................................................................................................................... 9
Soft-Start................................................................................................................................................................. 9
Shutdown/Auto-Restart........................................................................................................................................... 9
Hysteretic Over-Temperature Protection................................................................................................................. 9
Bandgap Reference.............................................................................................................................................. 10
High-Voltage Bias Current Source........................................................................................................................ 10
Using Feature Pins ................................................................................................................................................... 10
FREQUENCY (F) Pin Operation........................................................................................................................... 10
LINE-SENSE (L) Pin Operation ............................................................................................................................ 10
EXTERNAL CURRENT LIMIT (X) Pin Operation.................................................................................................. 11
MULTI-FUNCTION (M) Pin Operation .................................................................................................................. 11
Typical Uses of FREQUENCY (F) Pin ...................................................................................................................... 14
Typical Uses of LINE-SENSE (L) and EXTERNAL CURRENT LIMIT (X) Pins ...................................................... 15
Typical Uses of MULTI-FUNCTION (M) Pin ........................................................................................................... 17
Application Examples .............................................................................................................................................. 20
A High Efficiency, 30 W, Universal Input Power Supply........................................................................................ 20
A High Efficiency, Enclosed, 70 W, Universal Adapter Supply.............................................................................. 20
A High Efficiency, 250 W, 250-380 VDC Input Power Supply............................................................................... 22
Multiple Output, 60 W, 185-265 VAC Input Power Supply.................................................................................... 23
Processor Controlled Supply Turn On/Off............................................................................................................. 24
Key Application Considerations ............................................................................................................................. 26
TOPSwitch-II vs. TOPSwitch-GX.......................................................................................................................... 26
TOPSwitch-FX vs. TOPSwitch-GX ....................................................................................................................... 28
TOPSwitch-GX Design Considerations ............................................................................................................... 28
TOPSwitch-GX Layout Considerations................................................................................................................. 30
Quick Design Checklist......................................................................................................................................... 32
Design Tools ......................................................................................................................................................... 32
Product Specifications and Test Conditions ......................................................................................................... 33
Typical Performance Characteristics .................................................................................................................... 40
Part Ordering Information ....................................................................................................................................... 46
Package Outlines ..................................................................................................................................................... 47
M
2
12/04
POWERINT [ Power Integrations ]
