I got a problem related the circuit below.

I wanted to make DAC (0-80V) using a pwm input (6 kHz). You might ask why I did not make it with a single n-mos. The reason for it, I used a single as well. But power dissipation could be a very big problem, if I need more than 100 DAC channel in a circuit.

So I decided to use c-mos , to get away this problem. Since I need high voltage, I chose PHC2300 and built up the circuit.

The problem starts hier. I tried at the beggining with 24 volt. it seems to be working. But afterwards, If I increase the voltage till 80V, the complimantary mosfet does not work anymore. I tried several time. İt happens againg and again.

Do you have any idea, what the reason could be ?

^{simulate this circuit – Schematic created using CircuitLab}