TOP242-250
2
H
9/02
Design Tools .........................................................................................................................................................33
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................................................................................................................................................9
High-Voltage Bias Current Source........................................................................................................................10
Using Feature Pins
.................................................................................................................................................... 11
FREQUENCY (F) Pin Operation........................................................................................................................... 11
LINE-SENSE (L) Pin Operation............................................................................................................................ 11
EXTERNAL CURRENT LIMIT (X) Pin Operation ................................................................................................. 11
MULTI-FUNCTION (M) Pin Operation ..................................................................................................................12
Typical Uses of FREQUENCY (F) Pin
......................................................................................................................15
Typical Uses of LINE-SENSE (L) and EXTERNAL CURRENT LIMIT (X) Pins
.......................................................16
Typical Uses of MULTI-FUNCTION (M) Pin
.............................................................................................................19
Application Examples
...............................................................................................................................................21
A High Efficiency, 30 W, Universal Input Power Supply........................................................................................21
A High Efficiency, Enclosed, 70 W, Universal Adapter Supply..............................................................................22
A High Efficiency, 250 W, 250 - 380 VDC Input Power Supply.............................................................................23
Multiple Output, 60 W, 185 - 265 VAC Input Power Supply..................................................................................24
Processor Controlled Supply Turn On/Off ............................................................................................................25
Key Application Considerations
..............................................................................................................................27
TOPSwitch-II
vs.
TOPSwitch-GX..........................................................................................................................
27
TOPSwitch-FX vs. TOPSwitch-GX .......................................................................................................................
28
TOPSwitch-GX
Design Considerations ................................................................................................................29
TOPSwitch-GX
Layout Considerations.................................................................................................................31
Quick Design Checklist.........................................................................................................................................31
Product Specifications and Test Conditions
..........................................................................................................34
Typical Performance Characteristics
......................................................................................................................41
Part Ordering Information
........................................................................................................................................45