Negative Bias for Graphics Displays

Hello Neil,

here is a schematic which should do the job.
Please note that there is no feedback/control loop. So the output voltage depends on the load current. With a nearly static load current the AVR can read the negative voltage with the help of two resistors and the ADC and then can control the PWM by the ADC results.

rolf

but please note also that with such an inverter the max. duty cycle is 50%

rolf