Semiconductor Group

34

TDA 4605

In the different load ranges the switched-mode power supply (SMPS) behaves as follow:

No load operation:

The power supply unit oscillates at its resonant frequency typ. 100 kHz to 200 kHz. Depending upon

the transformator windings the output voltage can be slightly above nominal value.

Nominal operation:

The switching frequency declines with increasing load and decreasing AC-voltage. The duty factor

primarly depends on the AC-voltage. The output voltage is load-dependent only.

Overload point:

Maximal output power is available at this point ot the output characteristic.

Overload:

The energy transferred per operation cycle is limited at the top. Therefore the output voltage

declines by secondary overloading.