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BQ76942: How do I wake up or bring out of shutdown on a BQ76942.?

William Meyer
Prodigy 100 points
Part Number: BQ76942

Tool/software:

Hello TI: I want totally struggling trying to get this bq76942 to operate. On the EVM, I set up all of the registers, verified proper operation and programmed the monitor IC. I replaced my part with the programmed part from the EVM. But I can't get the monitor to wake up or come out of shutdown. I am at a loss! Here is my schematic.

   

I am in need of some expert help. 

Thanks!

Bill 

  • 0
    TI__Genius 17835 points

    Hello Bill,

    Just from a quick glance at your schematic, I noticed that you had a thermistor on your TS2 pin. If the device is intended to enter SHUTDOWN mode, the TS2 pin should be left floating or else when you try to enter SHUTDOWN, it will get stuck in the SOFT SHUTDOWN state. That may be what is occurring. Do you mind following the FAQs below to see if that is potentially what you're seeing?

    1. Shutdown Mode FAQ
    2    . Soft Shutdown FAQ

    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Prodigy 100 points

    Hello Alexi:

    I have tried to remove the TS2 and let it float in an attempt to avoid shutdown. But the monitor still acts like it's in shutdown or sleep. Do I need a Wake button on TS2 like the EVM?  I was curious if my design inherently is connected in a way that makes exiting shutdown or sleep mode impossible. I just don't see it! I followed the EVM for nearly all of the design. 

    I will follow the FAQ looking for answers. 

  • 0 in reply to William Meyer
    TI__Genius 17835 points

    Hello William,

    If you can pull the TS2 low, it should also work to wake up the device. 

    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Prodigy 100 points

    Hello Alexis: I followed your links and found out I was not in shutdown because Reg18 was at 1.8V.  Further digging, I discovered I was missing a pull-down resistor on RST. Now, I'm able to get the monitor to activate Charge and Discharge FETs. But the FETs are turned on ONLY in charging mode. I'm not able to get the monitor to turn on the FETs in discharge mode. 

    This monitor IC worked fine while mounted on the EVM. In fact, while on the EVM I noticed the two FETs were turned on as soon as I loaded the GG file.

  • 0 in reply to Alexis_H
    Prodigy 100 points

    Hello Alexis: I followed your links and found out I was not in shutdown because Reg18 was at 1.8V.  Further digging, I discovered I was missing a pull-down resistor on RST. Now, I'm able to get the monitor to activate Charge and Discharge FETs. But the FETs are turned on ONLY in charging mode. I'm not able to get the monitor to turn on the FETs in discharge mode. 

    This monitor IC worked fine while mounted on the EVM. In fact, while on the EVM I noticed the two FETs were turned on as soon as I loaded the GG file.