TOP242-250
2
K
9/03
Design Tools .........................................................................................................................................................32
Package Outlines
......................................................................................................................................................45
Section List
Functional Block Diagram
......................................................................................................................................... 3
Pin Functional Description
........................................................................................................................................ 4
TOPSwitch-GXFamily 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 DC
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..............................................................................21
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-IIvs. TOPSwitch-GX..........................................................................................................................26
TOPSwitch-FX vs. TOPSwitch-GX .......................................................................................................................27
TOPSwitch-GXDesign Considerations ................................................................................................................28
TOPSwitch-GXLayout Considerations.................................................................................................................30
Quick Design Checklist.........................................................................................................................................30
Product Specifications and Test Conditions
..........................................................................................................33
Typical Performance Characteristics
......................................................................................................................40
Part Ordering Information
........................................................................................................................................45