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Original question:

BQ76930: Balancing over 2 cells causes balancing in another

BQ76930: TS1 Temp measuring

Js H
Prodigy 10 points
Part Number: BQ76930

Hi： Dear   TI's   engineer &everyone,thanks  for   reading

        Now  I'm  using  Bq76930   for   BAT  Vol &temp   measuring,But  Temp   measuring  is  not   correct  when   i   pull  out   thermistor   resistor   to   simulate   open  wire.

        After   pulling  out   thermistor   resistor, the waveform  on   TS1  pin   is  a   periodic   pulse   signal, and   the   platform  is  3.3V， there's  no    abnormal   phenomenen.But  the   data  read  from  register   is   not match  with   3.3V, the  data  can  be   1.5V   and   other  value   smaller    than   3.3V.

        the  circuit   of   TS1  pin   is   simple, only  a   4.7 nF  cap  is   put    between   TS1  pin  and   ground,the   boot  signal   is   sent   through   a  diode   to   TS1   pin. 

        I  can't  figure  out    the  key  point  and  how  to  solve  this   problem,looking  forward  your  replying

   best    regards!

        

     

  • 0
    TI__Guru* 81034 points

    Hi JS,

    The pulse signal is normal - the TS pins are sampled every 2 seconds to get a temperature reading (see Temperature Measurement Interval on page 13 of the datasheet). I'm not sure I understand why you are removing the thermistor resistor from TS1 - I don't think you should expect a valid reading in this case.

    The SYS_CTRL1 register has a bit, TEMP_SEL. By default this bit is set to zero - this means that temperature sensor readings will be from the internal temperature sensor and not from the external thermistors. Make sure to set this bit if needed.

    Best regards,

    Matt