AN1330 datasheet(27/31 Pages) STMICROELECTRONICS

27 / 31 page

AN1330

Application ideas

27/31

6.3

Dual output voltage with auxiliary winding

When two output voltages are required, it is possible to create a dual output voltage

converter by using a coupled inductor. During the ON phase, the current is delivered to

VOUT while D2 is reverse-biased.

During the OFF phase, the current is delivered through the auxiliary winding to the output

voltage VOUT1. This is possible only if the magnetic core has stored sufficient energy. So, to

be certain that the application is working properly, the load related to the second output

VOUT1 should be much lower than the load related to VOUT.

Figure 27.

Dual output voltage with auxiliary winding

6.4

Synchronization example

Two or more devices (up to 6) can be synchronized simply by connecting the

synchronization pins. In this case, the device with a slightly higher switching frequency value

will work as master and the ones with a slightly lower switching frequency values will work

as a slaves.

The device can also be synchronized from an external source. In this case the logic signal

must have a frequency higher than the internal switching frequency of the device (250 kHz).

Figure 28.

Synchronization example

AN1330 Arkusz danych(PDF) 27 Page - STMicroelectronics