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BQ24640: when is supercap fully charged?

Renan Santos Adriano
Genius 16540 points
Part Number: BQ24640
Other Parts Discussed in Thread: TLV840

Hello Team,

Posting on behalf of my customer:

Hi - I'm trying to finish a bq24640 design but...

The datasheet table 2 says STAT goes on (OC low) when CE is high and blinks on fault condition or CE off.
Figure 7 shows STAT goes low and stays low (after initial glitch at turn-on).

However, what I (and most folks using supercap for ride-through) need is to know when supercap is charged,
as it must be fully charged before I can start IO activity that requires ride-through (ie writing to flash).
How do I determine supercap is fully charged?

Regards,

Renan

  • 0
    TI__Guru*** 143950 points

    Hi Renan,

    Unlike a LiIon battery that requires terminate, supercaps don't require terminate so the charger operates more like a dc/dc converter and constant refreshes (tops offs) the cap voltage.  If you need to know then the supercap is charged, you can monitor the FB pin voltage.  When V(FB)=2.1V, with MCU ADC or SVS like TLV840, the supercap is charged.

    Regards,

    Jeff