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Original question:

bq34z100 TS pin pull-down

BQ34Z100-G1: TS pin internal pull down resistor

Milan Djordjevic
Prodigy 60 points
Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: BQ34Z100-R2

Tool/software:

Dear Sir/Madam,

I would like to use your BQ34Z100-R2 chip for measuring battery parameters. I have some questions regarding temperature measurement using an NTC thermistor. Does this measurement directly factor into various calculations of the chip, or is it used for battery overheating protection or something else? Does the P6/TS pin have an internal pull-down resistor, and if so, what is its value? Since the NTC measuring the battery temperature is quite far, can I emulate the voltage value on this pin using a DAC if there is an internal resistor to ground from this pin, so that the DAC generates a voltage equivalent to the temperature of the NTC located far on the batteries?

Best regards!

Milan

  • 0
    TI__Mastermind 26995 points

    Hi Milan,

    Accurate voltage, current, and temperature reading are required for accurate gauging. The thermistor should be placed on the battery pack.

    There is an internal LDO on the TS pin that is used to read the thermistor, I recommend using the device as intended.

    Regards,

    Diego

  • 0 in reply to Diego
    Prodigy 60 points

    Dear Sir/Madam,

    As I understand, the LDO output is on the reg25 pin, which provides 2.5V at the output, and an NTC is connected to it, with the other end connected to the TS pin. Our system is not designed to have a thermistor here. Is there an internal pull-down on this pin, and if so, what is its value? Since this is far from the batteries, using an NTC with 10m wires will create significant problems during EMC testing. We have a unit that reads voltages on 18 cells and one temperature. We have several such units for reading, and all are connected to ISO SPI. Thus, we have multiple temperature measurements across the entire string. Therefore, with a short cable, we measure the temperature and cell voltages because these units are directly on the batteries. Since we measured the temperature there, we will transfer it via ISO SPI to the MCU, and it will command the DAC to generate a voltage that is adequate for each temperature value, ranging from 50mV to 1V, which is the measurement range of the TS pin. If it has a pull-down, we can certainly do it this way. Is there a resistance to ground, and what is its value?

  • 0 in reply to Milan Djordjevic
    TI__Mastermind 26995 points

    Hi,

    There is an internal resistor, I will need to ask design for the exact value, pleaser allow me sometime.

    Regards,

    Diego

  • 0 in reply to Diego
    Prodigy 60 points

    Ok, thank you very much. I look forward to your response.

  • 0 in reply to Milan Djordjevic
    TI__Mastermind 26995 points

    Hi,

    There is a 5K ohm internal resistor on the TS pin connected to gnd.

    Regards,

    Diego