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Original question:

TPSI2140-Q1: I am using TPSI2140QDWQRQ1 for 150Volts BMS Isolation detection

TPSI2140-Q1: Isolation detection using BQ79731

Nishant Gupta
Prodigy 95 points
Part Number: TPSI2140-Q1
Other Parts Discussed in Thread: TIDA-01513, BQ79731-Q1

Tool/software:

Previous thread that of same IC I have opened. Want to clear that I am using BMS IC bq79731-q1 .And for that I want to clear that I want to do isolation detection for my 150 volts battery pack.I have to use external circuit with TPS12140-q1 solid state relay and OPAM circuit as present in the reference design of TIDA-01513. Or is there any feature in BQ79731-q1 ic to measure high voltage and calculate insulation resistance with tps12140 ICC 

  • 0
    TI__Intellectual 1250 points

    Hello Nishant, 

    Thank you for reaching out with these BQ79731-Q1 specific inquiries. I have reached out to the relevant group responsible for BQ79731-Q1, and they should be in touch soon.

    Best,

    Hussain   

  • +1
    TI__Expert 7636 points

    Hello Nishant,

    At a high level, insulation monitoring is just a big resistor divider used for measuring the insulation resistances in the system. When the insulation changes value, the divider will measure a different voltage. The BQ device should be able to calibrate these values and output warnings and faults when the insulation becomes too low, where it could damage the system or the end-user.

    BQ79731 EVM features insulation monitoring and high voltage measurement circuits so I would imagine it works well for those applications.

    I've also attached the calculator tool requested in your direct message, I think for a max 155 V system, you may want to output at most 3.3 V if one of the insulation resistances is completely shorted. So a 1:46 divider ratio should accomplish that, which is why I have input 460 kΩ for the series resistance and 10 kΩ for the output resistance.

    Anthony should be able to help with further BQ79731 questions.

    BMP_IRM_VCHx_calculator (1).xlsx

    Best regards, 
    Tilden Chen

    Solid State Relays | Applications Engineer