• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 46 subscribers
  • Views 249 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

ADS122C14: The way to cut off the bridge current during power down

Shinichi Inoue
Guru 22481 points

Part Number: ADS122C14
Other Parts Discussed in Thread: ADS1220

Dear Specialists,

My customer is interested in ADS122C14 as a successor to ADS1220 and have a question.

I would be grateful if you could advise.

---

We are cousidering to use ADS122C14 for a battery application, for example solar of wireless charging. And bridge sensor is used.

When using the ADS1220, the low-side power switch in the device was set to automatically open during POWERDOWN. This turned off the bridge current and reduced power consumption.
image.png
The ADS122C14 no longer has a low-side power switch. Instead, by using REFOUT for bridge excitation, as in the circuit on the right, it seems possible to turn off the bridge current during POWERDOWN. Is this usage intended, or is it possible to implement it without any problems? 

image.png

 

Or could you please advise another way to off bridge current at powerdown.

---

I appreciate your great help in advance.

Best regards,

Shinichi 

  • +1
    TI__Mastermind 25035 points

    Hi Shinichi-san,

    your proposal will work with the ADS122C14. The voltage reference is powered down in power-down mode so that no voltage is driven on the REFOUT pin. You just need to take the reference voltage start-up time into account when you are coming out of power-down mode.

    Another option would be to leverage one of the GPIOs and control an external switch (e.g. FET) placed between GND and the bridge that can then disable the bridge. 

    Regards,
    Joachim Wuerker

  • 0 in reply to Joachim Wuerker
    Guru 22481 points

    Hi Joachim,

    Thank you for your reply.

    I talked about your suggestion with the customer.

    They wouldn't like to add external switch, so they'll think to use REFOUT.

    When the customer has an additional question, I consult you with another thread,

    I appreciate your great help and cooperation.

    Beat regards,

    Shinichi

  • 0 in reply to Shinichi Inoue
    TI__Mastermind 25035 points

    Sounds good Shinichi-san.

    Another option would be to use the integrated excitation current sources to excite the bridge with a constant current instead of a constant voltage.
    You can enable and disable the current sources through the register settings.

    Regards,
    Joachim Wuerker