I'm designing a programmable bench power supply (PS) that has multiple isolated channels (each powered by a separate transformer winding). I like the idea of isolated channels so that multiple channels can be connected in series to generate dual-polarity output (like -15/0/+15 V). The idea was to use a microcontroller (MCU) to set the output voltage and current limits of each channel using analog voltages from the MCU's DAC (or an external DAC IC controlled by the MCU). Given that channels are able to float with respect to one another, what would be the best way to ensure that the control voltages sent from the MCU to each PS output channel are properly referenced to the channel's voltage level?
The options that I've come across so far are to either:
- (analog approach) use an isolation amplifier between the DAC and each PS channel
- (digital approach) use a separate DAC IC for each PS channel and digital isolators to interface each DAC with the MCU.
I'm curious to know if there is a standard approach to this type of problem as I imagine that this comes up in many bench supply designs. Thanks!