Need PIC16F872 5VDC Regulator Circuit Suggestions

[dougm]

We have a 12VDC - 2 Amp Heating system for small animals. The PIC16F872 is controlling temperature. We are buffering the PIC from the heater with a MOSFET driver IC and an IRL540. The heater does generate noise when it is switched ON/OFF - we installed a 1N5822 freewheeling diode across the heating element to help reduce switching noise.

My question is: How do I best protect the PIC from voltage spikes generated by the heater? We currently are using a LM7805 w/ a 4.7 ufd tantelum cap, and a 0.10 ufd ceram mono cap at the 5VDC output. Are there any better suggestions? Should I include a TVS device or any other parts to properly protect the PIC?

[SimpleAsPossible]

You could throw together a simple low-power isolated switching supply with linear post-regulation for the PIC, then drive your MOSFET driver with an isolated switch (optocoupler, perhaps?).

There should be many app notes describing circuits that are close to this....