This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADC1175: Problem when unpluging the 5V supply

Part Number: ADC1175

Hello all,

To try to save energy, I turned off the 5V supply on the ADC1175. However, through the 3V3 input supply, the ADC was generating (I do not know how) 1.9V at the 5V power rail. This 1.9V would then feed the remaining circuits connected to the 5V rail.

What is causing this problem? Is there any way to turn off the ADC completely?

Regards,

João Rego

  • Hi João,

    We don't have any of this device in our lab so I cannot test unfortunately. Can you share the left side of the schematics which are cut off regarding the VRT, etc. My guess is that some of the VRT is leaking. Instead of powering off only the 5V, powering off all supplies to the ADC will be the only way to properly power down this device. Once powered back on, give the device 2 clock cycles before data is valid. The device mentions some power saving technique by leaving the clock at a logic low after a conversion cycle, please see the section THE ADC1175 CLOCK 

    Thanks, Chase

  • Hi Chase,

    Here is the left side of the schematic.

    I understand that, due to this problem when powering off the 5V, I need to power off also the 3V3. This was my first thought.

    Thank you.

  • Hi Joao,

    Does this solve your issue?

    Thanks,

    Rob

  • Hi Rob,

    Yes, turning off both supplies (5V and 3V3) solved the issue. To turn off these supplies I will use a P-MOSFET.

    Thanks.