FA5540 Fuji Electric holdings CO.,Ltd, FA5540 Datasheet - Page 24

• Manufacturer Part Number: FA5540
• Description: Fuji Switching Power Supply Control Ic
• Manufacturer: Fuji Electric holdings CO.,Ltd

Rev.0 July-2007
■FA5541 (auto restart type)
If an overload condition continues more than 200ms, switching is forced to shutdown using an internal timer.
In addition the startup circuit is possible to operate within 1600ms from beginning of an overload condition.
If an overload condition continues, switching is done for 200ms and after that Vcc is provided by a startup
circuit for 1400ms and the operation halt condition is maintained.
When 1600ms passes after beginning of an overload condition, a startup circuit stops its operation and Vcc
begins to drop. When Vcc decreases to 9.0V, IC is once reset and restarted. Since then startup and shutdown
are repeated if an overload condition continues. If load returns to normal, IC returns to an ordinary operation.
However, the output voltage must rise up to the setting value within 200ms settled by the timer at the startup.
Timer
output
FB pin
Vcc
Switching
operation
Start up
circuit
Timer
1600ms
200ms
12.4V
10.2V
9.0V
3.3V
Normal load
200ms
Fig.8 Operation at overload (FA5541)
200ms
FA5540/5541/5542
1600ms
24
Over load
Fuji Electric Device Technology
Normal load