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BQ76PL455A: How bq76PL455 calibrate internal temperature sensor?

Part Number: BQ76PL455A

Dear Sir/Ms.

Q1: How to calibrate the temperature measurement of the internal chip of the PL455?
Q2: Passively balanced resistance, how to adjust and calculate the resistance value? Is there a formula?

Best Regards,

Kami Huang

  • Inside the IC there are 4 sensors. The analog and Digital each have (a) Thermal Shutdown circuit(TSD) and separate Sensor. TSD are FIXED and cannot be changed. To measure cell temp via NTC, the measurement are performed thru AUX0-AUX7 and set in the AUX OV/UV threshold registers. the threshold need to be programmed.

    refer to the VSENSE connections for selection of the top stack and bottom cell configuration. Please refer to the Fig 38 of the d/s. also please refer to the SLUA791 Application note, " bq76PL455A-Q1 design recommendations". document is downloadable from the ti.com web site from the product folder in Ti.COM.
  • Hello Vish,

    just confirmed with RD that their problem has not been solved? The customer said that the situation they encountered was that the temperature measurement was not accurate. Temperature measurement on the customer's own PCBA. Use TI's GUI to measure the customer's PCBA. The room temperature is 27 degrees C but the PL455A returns is 42 degrees C. Whether it is Digital Temp or Analog Temp. Excuse me, where is the customer's inspection?

    Best Regards,

    Kami Huang

  • the temp measurement of the anlaog-die is programmable as part of the ADC seq. SET CHANNELS[CMD_HTSEL] The report value is the voltage from temp sensor, NOt the actual temp. Use VADC = [2 * VREF/65535] * READ_ADC_VALUE.
  • Hello Vish,

    Confirm with the customer this morning whether the problem is solved. The customer follows the NTC connection on the DETASHEET of BMS 455.

     

    There is no way to measure the required temperature message. How can I modify it?

    The customer tried to connect the NTC to the PL455A Vref pin and found that the correct problem could be measured. The customer wants to connect to the NTC using VREF.

    There is no VREF Iout written in the datasheet. How much current can be supplied from the IC VREF of the PL455?

    Best Regards,

    Kami Huang

    DEAR KAMI
            如電話所問,我們依照BMS 455 DETASHEET 上的NTC接法
    沒辦法量測到需要的溫度訊息,請問要怎麼修改呢???
    還有我們BMS 455 的這顆IC VREF這支腳的電流可以供到多少呢???

  • Hello Vish,

    Confirm with the customer this morning whether the problem is solved. The customer follows the NTC connection on the DETASHEET of BMS 455.
     
    There is no way to measure the required temperature message. How can I modify it?
    The customer tried to connect the NTC to the PL455A Vref pin and found that the correct problem could be measured. The customer wants to connect to the NTC using VREF.


    There is no VREF Iout written in the datasheet. How much current can be supplied from the IC VREF of the PL455?

    Best Regards,

    Kami Huang

  • Hi Kami,
    the VREF is output filter pin. It is used internally and we *do not* recommend connecting any circuits off the VREF pin and to pull current out of it. Thus we do not spec a load current for VREF.

    hope this helps,
    regards
    vish
  • question replicated twice. Please refer to previous post for answer.
    txs
    vish
  • Hello Vish,

    The key point is that the customer can't connect VREF, and then DATASHEET tells us that the following Fig 30 connection can be accurately measured, but the customer can't get the similar value according to the following formula. What should the customer debug direction do? Would you please help the revew circuit diagram? Can I email the customer's circuit diagram to you? The customer now uses the GUI to read the temperature. How can I read the scratchpad Read_ADC_value?

    Best Regards,

    Kami Huang

  • INT_TEMP is fixed; its not for sensing cell temperatures.

    Digital die temp can be measured via the ADC by setting CHANNEL[CMD_TSEL] bit.IN

    the conversion formula Internal Die temp is given by the equation (4) in the same section.

    INT_OT_THRES. Is written at test in the register address x550-x551 in the EEPROM.

    If the internal temp exceeds this value, INT_TEMP_FAULT will be set.

    The internal register is being set @ 0xAB68.  In decimal, 43889

    5V full scale is, 0xFFFFà65535 ; so 0xAB68,

     

    VADC = (43889/65535)* 5V = 3.3478V…

     

    From d/s equation #4,

     

    INT DIE temp C = (3.3478-2.287) *131.944 =139.9C……..

  • Hello Vish,
    Thank you allow me check with my customer.
    Best Regards,
    Kami Huang
  • OK will close this old string of email.