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BQ2980: PTC temperature cutoff

RodneyFarrow
Expert 4010 points
Part Number: BQ2980

HI Guys

The BQ298000 does support a PTC for temperature cutoff, however in order to enable this functionality there is a factory enabled internal pullup resistor that needs to be enabled. The datasheet doesn't give an MPN that corresponds to any of this family of devices having this enabled. I don't care which of the pullups are enabled, as I can select a PTC to match, I obviously just need to know which is enabled.

I am trying to determine if it is actually need the pullup, it seems that without it the pin is still a voltage sensitive pin and so I can use a PTC/NTC to trigger it at it's specific level quite easily. But I am struggling to understand the datasheet regarding if this would be possible. There is a SHUTDOWN mode that it enters if this pin is pulled high for too long without the internal pullup enabled. And I cannot get a clear answer about what the implications of this mode are and whether this will be an issue for my design.

Please can you clarify?

Thanks

  • 0
    TI__Guru* 77283 points

    Hi Rodney,

    I think the problem here is that the CTR pin input range where it switches is quite large (0.4V to 1V) because it is really just a digital input. So the PTC/NTC would need to have a big enough change in resistance right at the temperature needed.

    Regards,

    Matt