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BQ76952: How to understand the value about CFETOFF pin in temperature ADC mode

Miles Li1
Intellectual 1640 points
Part Number: BQ76952

Team,

Customer is using CFETOFF pin as temperature sampling pin. In order to improve the temperature, they have set the CFETOFF register as :00111011, which means that they use this pin as temperature measurement, choosing 18k as pull up, but they don't use the thermal algorithm of BQ76952.

At this time, they have read value of 455. My questions is:

1) What does this value mean?

2) What is the relationship between this value and actual voltage on NTC?

Wish to get your reply, thanks!

  • 0
    TI__Guru 54715 points

    Hi Miles,

    The technical reference manual shows all bit combinations, but they don't all result in meaningful values.

    1. Its value is unknown.

    2. The value is some calculation based on a ratiometric measurement with the supply.

    If you want to measure the voltage of the input you should use a setting of 0xB3.  Enabling the pull up puts the part in some temperature measurement mode.