BQ76920: Alert period accuracy

Jeffrey Wright

Part Number: BQ76920

Hello;

When does the 920 raise the ALERT signal in response to an OCD or SCD event, relative to the normal (synchronous) 250 ms CC conversion period ?

That is, is it asynchronous to the 250 ms CC conversion period?, or is the ALERT signal period always 250 ms, and an OCD/SCD event will not asynchronously raise the ALERT signal?

I assume that the accuracy of the 78350 Fuel Gauge depends upon the accuracy of a known, constant ALERT period for CC...

Thanks

over 5 years ago

0 Matt Sunna over 5 years ago

TI__Guru* 81034 points

Hi Jeff,

The measurement loop for the BQ76920 is on a 250 ms period and the ALERT signal will assert when new measurements are ready. OCD and SCD are not triggered by ADC measurement, but by hardware comparators so the ALERT signal will be asserted independently.

The OCD timer is synchronized to a 2.5 ms tick, so there is a 0-2.5 ms delay before it is first detected.

Best regards,

Matt

0 Jeffrey Wright over 5 years ago in reply to Matt Sunna

Expert 2875 points

Ok, thanks Matt;

Will the 78350 continue to do gauging during an OCD event? For ex., my OCD trigger is 250A for 30 seconds. So during that 30 seconds prior to opening the discharge FET, does the fuel gauge continue to collect CC data?

Thanks

0 Matt Sunna over 5 years ago in reply to Jeffrey Wright

TI__Guru* 81034 points

Hi Jeffrey,

Yes, it should still continue gauging.

Matt

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BQ76920: Alert period accuracy