bq24270 low-power modes

Scott Brenneman

Other Parts Discussed in Thread: BQ24270

I'm trying to understand better the behaviors of the bq24270 in its various low-power modes. The triggers for those modes appear to be the CD input, the level of incoming power (VUSB), and the /CE bit in the Control Register.

1. Are the CD input and the /CE bit identical, or is there a difference?

2. Do CD and /CE have any effect if VUSB is below the undervoltage threshold?

3. Is there any problem with logic high levels being present on SCL, SDA, etc. when VUSB is not present?

Thanks,

Scott

over 9 years ago

0 Jeff F over 9 years ago

TI__Guru**** 173246 points

Regarding 1, no. CD is chip disable causing the charger to enter HiZ, low power mode where battery only powers the system.
Regarding 2, no. If input voltage is below UVLO, the IC is disabled and battery only powers the system. Similar to HiZ but even lower power consumed.
Regarding 3, no.

0 Scott Brenneman over 9 years ago in reply to Jeff F

Genius 3295 points

Hi Jeff,

Thank you for responding. For question 1, I want to make sure I understand: The /CE bit does not result in as low a current as the CD pin disable does, correct?

And, if we don't have a reason to disable charging with charge power supply connected, we can just ignore CD and let UVLO do the job, correct?

Thanks,

Scott

0 Jeff F over 9 years ago in reply to Scott Brenneman

TI__Guru**** 173246 points

/CE only disables charge, not the buck converter. So, if you have a load on SYS, the buck converter will still try to provide power to the SYS output. The battery would only supplement power to SYS if the buck converter's input source could not provide the power.

0 Scott Brenneman over 9 years ago in reply to Jeff F

Genius 3295 points

Okay, I believe I understand the distinction. Thank you for explaining it.
Scott

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bq24270 low-power modes