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BQ77216: BQ77216

Ankur Kushwaha
Prodigy 20 points
Part Number: BQ77216

Tool/software:

1. While testing bq77216 we have observed the following condition for OT error ( Multiple test)  :

a) Both COUT and DOUT goes high ( 7.23V) when resistance drops below 1525R 
b) Both COUT and DOUT goes low when resistance rises above 1950R 
 
2.However in the datasheet hysteresis given is 4186R and 3530R. Please confirm if it is correct.
 
3. What is the voltage used for the internal pullup resistor ( 20K) ?
  • 0
    TI__Mastermind 40090 points

    Hello Ankur, 

    I would recommend to measure the resistance after the trigger point. Usually connecting a probe or DMM during the measurement may cause some error on the trigger. I remember I had the same problem before. Once I started measuring after the trigger point, I saw it was very accurate.

    Now, the pull-up voltage is 1.5-V.

    Best Regards,

    Luis Hernandez Salomon

  • 0 in reply to Luis H. S.
    Prodigy 20 points

    Hi Luis,

    1. DMM is disconnected during the experiment till the trigger point is hit for both event ( low to high and high to low ) . Once the trigger point is hit, I turned off the power supply and connected the DMM.

    2. It seems hysteresis is also given in terms of temperature. For temperature it is given -10°C which corresponds to 1950R ( 73°C)  as given in the datasheet of NTC ( 103AT) used in EVM of BQ77216 and is found to be correct for device with OT of 83°C ( our device) 

    3. It seems 4186R corresponds to 52°C (-10°C hysteresis)  for device with OT of 62°C and is not for device with OT of 83°C . Since the datasheet is common, I think hysteresis in terms of resistance is given for device with minimum OT of 62°C only.  Snippet attached for reference.

  • +1 in reply to Ankur Kushwaha
    TI__Mastermind 24260 points

    Hi Ankur,

    You're correct. The hysteresis values in the hysteresis section that are in ohms are just for the 62C and 65C trigger options. For the other settings, you would just use the resistance listed for the trigger point that the hysteresis value lines up with, i.e. for an 80C or 1651 ohms trigger, the hysteresis would be at 70C or 2195 ohms.

    Looking at your original post, it seems like you were seeing the expected behavior.

    Regards,

    Max Verboncoeur