Hi Guys,
I'm designing a low-power isolated supply (3.3V, Max ~50mA) and am keen to steer clear of transformers as EMI is critical to the design and I've had some noise issues with my previous transformer-based design.
I have been looking at using a capacitively-coupled circuit plus bridge rectifier as per Maxim's AN4553 app note - see below (or a similar charge-pump type circuit which will allow me to get ~150mW of power across the isolation caps) but their MAX256 chip is far overspec'd from a power (and size/cost) point of view (3W) for my requirements.
Do you have any suggestions for a driver to replace the max256 here, which would differentially drive a square wave into a circuit like this at <2 MHz? Or is there an alternative way to achieve a capacitively coupled low power supply? I've had a look at some cmos drivers, even 555 timers, but nothing seems to provide the combination of (a) required source/sink output power and (b) dual, complimentary square wave output I require to drive into the capacitor/bridge circuit.
Since it is such a low power application, am hoping there is a cheap, small, quiet way to do this easily, but so far I haven't found it.
Thanks in advance,
Dave
