BQ25895: Source of logic high for OTG pin

Tishampati Dhar

Part Number: BQ25895

The recommended approach to enabling OTG is to pull the pin high and write the OTG register. I would like to know the source of the logic high on battery based systems. Will a 10k resistor to PMID suffice ? Are there additional considerations ? Datasheets note that this pin can handle upto 7v and PMID should at least output battery voltage - mosfet voltage drop. So tying OTG to that should achieve a logic high for 5v output on PMID purposes.

over 5 years ago

0 Tishampati Dhar over 5 years ago

Prodigy 40 points

I have tested with pulling OTG pin to PMID and 5v output activates. However powering the load from OTG seems unreliable, as opposed the previous approach I had using VUSB and VBAT directly using a pair of Schottky diodes in Power OR configuration. Currently removing the VUSB causes load to lose power, when VUSB is plugged back it load does not power back on. All power has to be removed and re-connected to allow powering the load from PMID. The load expects a 3.3v power and uses a TLV1117-3.3v LDO between PMID and load.

0 Ning T over 5 years ago in reply to Tishampati Dhar

TI__Guru 57781 points

Hi,

Referring to the BQ25895 EVM design (https://www.ti.com/lit/ug/sluuba2b/sluuba2b.pdf), the OTG pin is pulled up by SYS or BAT pin.

Thanks,

Ning.

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BQ25895: Source of logic high for OTG pin