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BQ24192: Solution to short term data logger battery + charger

stomp
Genius 4675 points
Part Number: BQ24192
Other Parts Discussed in Thread: MSP430F5529, , TPS61291, TPS22860, BQ25892

Hi,

Designing a product running from one 700mAh Li-Ion cell.  MSP430F5529 and some sensors, device has to wake up every 15 min, take a sample and go back to sleep. Run time is 2 weeks (336 hours). USB connector is provided for charging and data. Power budget for the rest of the system is not set yet.

Looking at the BQ24192 device, it seems that in its lowest power mode it will consume 4mA.  This alone yields only 175hrs on a 700mAh pack.

So the next option I have is to use a system timer like a TLP5111 to power everything up, but the BQ24192 seems to lack a 'power off" control signal.

If I could somehow switch off the BQ24192  I would still need a TPS61291 as a boost converter to power the TLP5111 timer to drive a TPS22860 load switch power the BQ24192....  which is just messy.

Does anyone know of a device like a BQ24192 that would be more suitable for use as a Li-Ion battery interface in a short term data-logging solution that could be powered off, put to sleep or has an integrated lowIq LDO for a system timer?

Thanks

Stomp!

  • 0
    TI__Expert 8230 points

    Hello,

    stomp said:
    If I could somehow switch off the BQ24192

    By this, do you mean to turn off the system (SYS =0V) or keep the SYS powered by battery but cut off the power from the converter.

    The bq24192 allows the host to turn off the internal BATFET via I2C to cut off the power from the battery to the system. The problem with this is, that if you do this, your host will power off as well and the only way to turn on the FET would be to apply the VBUS.

    You could power the LDO for the MSP430 and the I2C pull-ups directly from the battery, but this will affect performance since your battery will always be discharging. You could place the MSP430 in LPM3.5 or similar and the test the runtime of your battery in these conditions.

    If you wanted to cut off the power from the adapter, you can use the host to place the device in HIZ, which turns off the internal LDO and places the device in a low quiescent state.

    I recommend also reviewing the bq25892, which is very similar to the bq24192 but has lower quiescent currents than the 192.

    Hope this helps.

  • 0 in reply to Fernando Lopez
    Genius 4675 points
    Thanks very much.

    The BQ25892 seems much better for the job.

    Regards.