FA5540 Fuji Electric holdings CO.,Ltd, FA5540 Datasheet - Page 22

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

Rev.0 July-2007
(3) Startup circuit and auxiliary winding voltage
In case that the auxiliary winding voltage is higher than 10.2V, the startup circuit operates only at the
startup and operates afterwards as a power supply using the auxiliary winding voltage.
On the other hand, in case that the auxiliary winding voltage is lower than 10.2V, the startup circuit
continues to keep Vcc between 10.2V and 12.4V by switching ON-OFF of the startup circuit.
Fig.6 Startup and shutdown (The auxiliary winding voltage is lower than 10.2V)
Switching
スイッチング
スイッチング
Switching
Start up
Start up
circuit
circuit
12.4V
10.2V
12.4V
10.2V
9.0V
9.0V
Vcc
Vcc
Fig.5 Startup and shutdown (the auxiliary winding voltage is higher than 10.2 V)
FA5540/5541/5542
22
Fuji Electric Device Technology