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BQ20Z655-R1: No LCD display

Part Number: BQ20Z655-R1

I'm able to communicate to my prototype board with BQ evaluation software, but I have a few problems that I've encountered as follows:  

1. I can't get the LCD to display any bars.  I’ve set the LCD mode in the Cfg C bits and the LCD appears to be wired correctly. 

2. I don’t have any voltage on the pack output pins.

3. The temperature measurement is extremely high and I see OT Discharge (OT1D) Flag bit set.  I don’t have any TS circuitry so this is coming off the IC internal reading.

  • Hi Kyle,

    Thanks again for posting this. Please check your Operation Cfg A settings for the thermistors. TEMP1, TEMP0 should be set to 0, 0 to use the internal temperature sensor only. If the external thermistor setting is used, it will read a very high value if not populated.

    Looking at the screenshot you shared via email, I think you have the default setting (external TS1 input used) which would result in the high temp that you are seeing.

    As the the LCD issues, are you able to share your schematic?  Please share via email if needed.  

    Thanks,

    Phil

  • Phil,

    That worked for the temperature setting and cleared the OT1D.

    Thank you,
    Kyle
  • Hi Kyle,

    Great. To close this thread out, adding pullup resistors to the LCD lines got the display working.

    Let us know if you have any further questions or are running into any additional issues.

    Thanks,

    Phil