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
  • I am using AD669 in bipolar and we are facing the issues . 

    following are the details of the circuit

    1. /CS, /L1 and LDAC are all tied each other.

    2. To write data we are following timing diagram of figure 1b from datasheet

    3. /CS, /L1 and LDAC (control signals) we are making initially  high then Low-> data -> control signals high -> control signal low.

    4. Negative output voltage we are getting as per data but positive voltages we are not getting.

    5. Some time negative output voltages also we are not getting

    6. Schematic is 

    Kindly help us to resolve this issue. Any care should be taken while power on and power off condition?

Reply
  • I am using AD669 in bipolar and we are facing the issues . 

    following are the details of the circuit

    1. /CS, /L1 and LDAC are all tied each other.

    2. To write data we are following timing diagram of figure 1b from datasheet

    3. /CS, /L1 and LDAC (control signals) we are making initially  high then Low-> data -> control signals high -> control signal low.

    4. Negative output voltage we are getting as per data but positive voltages we are not getting.

    5. Some time negative output voltages also we are not getting

    6. Schematic is 

    Kindly help us to resolve this issue. Any care should be taken while power on and power off condition?

Children
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