AD669 output @ power-down

Dear All,

In my design i used AD669 DAC with unipolar config.

During power down, although LDAC is at ground level and parallel bus is at zero logic DAC output stays 10V while system is shutdown (nearly a few msec).

And since DAC output is 10V the circuit controlled by DAC behaves out of our scope and damage the mechanical parts.

Could you pls help me how can i prevent this?

Regards

Parents
  • Dear Miguel;

    Thank you for response.

    Yes, analog and digital powers are separated.

    During power down firstly 5V goes down, then +-15V and finally +/-HV rails.

    And CS,L1 and LDAC are all at zero level without even any instant glitch. And under this condition we got 10V at the output of DAC, very strange.

    Pls see the schematic below.

    Regards.

Reply
  • Dear Miguel;

    Thank you for response.

    Yes, analog and digital powers are separated.

    During power down firstly 5V goes down, then +-15V and finally +/-HV rails.

    And CS,L1 and LDAC are all at zero level without even any instant glitch. And under this condition we got 10V at the output of DAC, very strange.

    Pls see the schematic below.

    Regards.

Children
No Data