I am looking to replace a classic 50Hz transformer/rectifier circuit with an SMPS. The input is to be 230VAC (EU) compliant and the output should be 5V/0.2A minimum while 5V/0.5A is a nice to have. An external adapter is not accepted (the apparatus also has a 230VAC output for pump control).
The cost of the current circuit is less than 2€ (50Hz transformer (1.05€), rectifier, regulator).
I've started by looking in to the lowest cost SMPS controller to find that the total BOM is quickly exceeding the origincal circuit's cost (100kHz transformer 1.1€, controller 0.2€, rectifier, optocoupler).
So the bigger transformer costs less than the smaller 100kHz transformer.
Should I be looking for an SMPS controller with higher switching frequency (does that exists) to get a smaller (cheaper) transformer or is it currently hopeless to design an SMPS that is cheaper that the classic 50Hz transformer centered design?
What is the best approach. Example: find the transformer first and then the controller?
Where's the state of the art of Isolated AC/DC SMPS at today ?
- looking at pricings for volumes of 2k to 10k/annum.
- The current power solution parts cost $2.5 (50Hz 220V/1.5VA transformer, bridge, caps and LDO).
- Must I conclude that the best AC/DC SMPS solutions are using around 100kHz, 15x15x15mm transformers, and that smaller (/cheaper) solutions using 1MHz for instance, a smaller transformer do not exist/are not available?
My conclusion after consulting several sources: - For a custom design the cost of an isolated SMPS is higher than simply rectifying and regulating the transformer output.
Thanks to all contributers for your feedbacks!