HVPS Code for an AVR

I'm wanting to use an AVR to generate the 180 volts to drive some nixie tubes. My thought is to set up a timer to generate a PWM signal which drives a MOSFET in a maner like the MAX1771. When the voltage gets above the threshholld, the CPU turns off the PWM signal until the voltage drops below the threshhold.

Does this sound like a reasonable aproach?

Yup. Works fine. I started with TimerOne.cpp from the Arduino. I arrived at the best period and duty cycle through experimentation.

I use the circuit below. Besides the usual buck-boost power mosfet (w/a driver), I have 220V TVS to protect for overvoltage. In addition, I sample the voltage with one of the adc channels and shut things down in case it goes over-voltage.