BQ76952: BQ76952 temperature sense issue

Star Xu

Part Number: BQ76952

The customer design with BQ76952. The internal pull-up resistor of the BQ76952 temperature measurement setting is 18K. From the data sheet, we know that the pull-up power supply is 1.8V.

If the outside temperature is 25°C and the resistance of the NTC is 10K, then the divided voltage value of the TS1 (use the TS1 channel to measure the temperature) pin should be 640mV. However, the actual voltage value measured with a multimeter is about 30mV, and this value is unstable.

The TS circuit as below:

Please help check it.

Thanks

Star

over 1 year ago

0 Max Verboncoeur over 1 year ago

TI__Mastermind 25750 points

Hi Star,

Could you get a waveform of the voltage across the thermistor with a scope?

Regards,

Max Verboncoeur

0 Star Xu over 1 year ago in reply to Max Verboncoeur

TI__Genius 9645 points

Hi Maxwell

Thanks for your help.

It can be seen from the following figure that there is a voltage plus.

Please help check it.

Thanks

Star

0 Max Verboncoeur over 1 year ago in reply to Star Xu

TI__Mastermind 25750 points

Hi Star,

The temperature sense on the device pulses so measuring with a multimeter that integrates the measurement won't be a good indicator of the actual voltage across the thermistor during measurements. The peak seems to be about 600mV which is what you were expecting for the correct value, so I believe there is no issue with the device.

Regards,

Max Verboncoeur

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BQ76952: BQ76952 temperature sense issue