BQ25628: REG0x14 Q1_FULLON bit and OTG operation

Gregor Christandl

Part Number: BQ25628
Other Parts Discussed in Thread: BQ25622, BQ25620

Datasheet section 8.3.10.3.1 states that

When the BQ25628 is in OTG mode, Q1 is off to block power from PMID to VBUS.

in section 8.6.2.9, REG0x14 bit 7 'Q1_FULLON' is described as

Forces RBFET (Q1) into low resistance state (26 mΩ) , regardless of
IINDPM setting.
0h = RBFET RDSON determined by IINDPM setting (default)
1h = RBFET RDSON is always 26 mΩ

can Q1 be forced into the low resistance state doring OTG operation, effectively allowing power to be sourced via the VBUS pin (instead of PMID)?

over 1 year ago

+1 Garrett Kreger over 1 year ago

TI__Mastermind 31510 points

Hi Gregor,

Thank you for reaching out via E2E. Please see my comments below.

On BQ25628 you are unable to force Q1 on during OTG operation. The device is specifically designed for PMID pin as output of OTG mode operation.

If you are looking for power to VBUS in OTG mode I recommend looking at the BQ25622 IC from the same product family. The BQ25622 does not turn off Q1 for OTG mode.

Best Regards,

Garrett

0 Gregor Christandl over 1 year ago in reply to Garrett Kreger

Prodigy 10 points

Hi Garrett,

thank you for pointing out the BQ25622! The BQ25620 seems to be the best part for my application since I do not need USB support.

+1 Garrett Kreger over 1 year ago in reply to Gregor Christandl

TI__Mastermind 31510 points

Hi Gregor,

To clarify BQ25620 has D+/D- pins for USB input type detection, whereas BQ25622 does not. Based on your description I believe BQ25622 will be the best option.

Best Regards,

Garrett

0 Gregor Christandl over 1 year ago in reply to Garrett Kreger

Prodigy 10 points

Hi Garrett,

you are right, thanks for the hint!

regards,

Gregor

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BQ25628: REG0x14 Q1_FULLON bit and OTG operation