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Bill, help!! About BQ500211 and BQ500211A

D kolar
Prodigy 20 points
Other Parts Discussed in Thread: BQ500211, BQ500211A

hi Bill,

    I have a BQ500211 transmitter and it works well.  Now,i want to change the BQ500211 replace into BQ500211A, but the transmitter works not well.

i know the 211 and 211A is pin to pin ,  also i add a resistor  connected between LOSS_THR (pin43) and GND ,and then put my phone NOKIA 920(or LG NEXUS4) on the transmitter,at first charge ok,  after about 5s .the transmitter red LED fast blink keep about 10s,the BUZ works once time,and red LED keep light--i am sure this mean is PMOD/FOD warning.

  At the beginning ,  I thought that maybe the LOSS_THR resistor value is too small,so i change the value from 42.2K to 200K, but the problem is same.  if i Take away the LOSS_THR (pin43) resistor ,leave this pin open , the  transmitter works well.

maybe the LMV931 and INA199A have Some of the differences,but i measured the voltage of I_SENSE ,the value about the same.

alse maybe some anyother circuit need to adjust,

so Bill, i need your help,, thanks !!

  • 0
    TI__Guru 69136 points

    When converting from the bq500211 to bq500211A three changes need to be made in the circuit.  Ref  bq500211A EVM for reference designators.

     

    1.)    R14 changes to 12.1k ohms. This will change Comm + bias voltage from 1V to 1.5V.

    2.)    U7 changes from LMV931 to INA199A1.  I_SENSE must be very accurate for FOD and the INA199A1 is better device for this purpose.

    3.)    Add resistor to set FOD threshold, pin 43 LOSS_THR.  Recommended starting value is 56.2k for 400mW.

  • 0 in reply to Bill Johns
    Prodigy 20 points

    hi Bill.

    Thanks again!