Low Cost 1W Power Supply Solution


Some industry applications (like isolated CAN transceivers) need a low powered isolated power supply. In such situations, a flyback converter can help thanks to their low cost and simple implementation.


You can build this flyback custom power supply using a non-synchronous reduced voltage boost converter. Next, it is time to design the transformer for the flyback converter.


Embedded engineers have two options here. You can use a maximum duty cycle in the pulse width modulation controller. Or you can use the secondary side’s reflected voltage. If you want to reduce cost further, use an auxiliary winding on the transformer’s primary side. It will do away with the optocoupler.


Note that when you use the auxiliary winding technique, you will have to contend with a reduced output load transition. On the opposite end, a secondary side control improves the output load transition. So a custom power supply has both advantages and disadvantages.


However, for the kind of industry applications we are looking at, this reduced output won’t make much of a difference. This shows an isolated custom power supply is possible without sacrificing efficiency. If you don’t want this, there is always an alternative- using a secondary side control with an optocoupler.