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 DC
MAX
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
2
M
12/04
POWERINT [ POWER INTEGRATIONS, INC. ]
