Other Parts Discussed in Thread: BQ25100, TIDA-00318
Hi
I'm intending to use the BQ51050B for charging a wearable with a tiny battery (in the order of a few mAh) and I have the following questions:
- Will this chip support charging such small batteries? I put RIlim to 330k which should give us just below 1mA. Could there be any issues within the whole system (Qi Tx to Rx)?
- The standby power drain of the chip is an issue (12uA as per datasheet), which would drain my battery within a few days, therefore I thought about adding an PMOS (Q1) between the BAT terminal and the battery as per schematics below. The datasheet states that the /CHG output is open drain, so this could theoretically work, unless there is a protection diode inside the chip between /CHG and the rail, which would obviously pull CHG low if there's no power to the chip. In this configuration the chip would be powered up once the Tx field is applied, it would think that the battery is depleted since there's no voltage on BAT, it will start with the precharrge, which in turn (I believe) will activate the PMOS connecting the battery to the chip. Could there be any other issue that I haven't thought about?
Thanks
Reto
