BQ40Z60 SMB Backfeed

Steve Widener

Other Parts Discussed in Thread: BQ40Z60

If there is unpowered logic "hanging" on the SMBC and SMBD lines of the BQ40Z60, will this cause any problem with the operation of the device? (Another way of putting this -> Is a buss isolation switch required when there is unpowered logic on the SMBC and SMBD lines).

over 9 years ago

0 Benjamin Lough over 9 years ago

TI__Mastermind 27105 points

Hi Steve,

The device should be fine without a bus isolation switch as long as the resistance and capacitance on your SMBC/SMBD lines is compliant to the SMB 2.0 spec.

Best Regards,
Ben Lough

0 Steve Widener over 9 years ago in reply to Benjamin Lough

TI__Genius 11010 points

Thanks Ben -

Just to be clear - if the BQ40Z60 is charging and then the SMBC & SMBD line are shorted to ground, the charger will continue to charge & operate properly - correct?

Steve

0 Benjamin Lough over 9 years ago in reply to Steve Widener

TI__Mastermind 27105 points

Steve,

You will want to make sure CHRGR_EN and CHG FET are both enabled in order to satisfy the conditions needed for charging. Page 56 of the reference manual goes into detail on this: www.ti.com/.../sluua04c.pdf.

Could you also elaborate on what is happening to your SMBC and SMBD lines? Are both lines being set to logic low? Are you trying to idle the SMBus?

Best Regards,
Ben Lough

Power management

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BQ40Z60 SMB Backfeed