BQ24295: Input Current Limit

Chuchen Wang

Part Number: BQ24295
Other Parts Discussed in Thread: BQ25895, BQ24297, BQ24296

Hi,

My customer has below questions:

For BQ25895 and BQ24295 - Is the input current limit enforced between VBUS and PMID pins?
For example, if I set the input current limit to 500mA and then load PMID with 600mA, will the input current be enforced?

My understanding from datasheet is: When there is input detected, input current limit is enforced. But when there is no input and boost current is sourcing from battery via PMID, then there is no current limit. Can you verify this is correct? I see we have bq24296 and bq24297 options which offers current monitoring.

Thanks,

Chuchen

over 7 years ago

0 Jeff F over 7 years ago

TI__Guru**** 166006 points

Hi Chuchen,

The FET between VBUS and PMID will not enforce the current limit setting. Charger input current is detected by the FET between VBUS and PMID. Input current limit is "enforced" by changing the duty cycle of the buck converter. So, the enforcement is only see by reduced output power at the SYS output of the buck converter.

0 Chuchen Wang over 7 years ago in reply to Jeff F

TI__Expert 3470 points

Hi Jeff,

My customer would like to understand:

How can we configure D+/D- pins to get the fastest response time between when 5V is present and the charger start pulling current?

We don't care about the D+/D- detection. We just want the charger to start charging as soon as possible.

Thanks,

Chuchen

0 Jeff F over 7 years ago in reply to Chuchen Wang

TI__Guru**** 166006 points

Chuchen,

The detection time is fixed but will conclude more quickly if D+ is tied to D-.

0 Chuchen Wang over 7 years ago in reply to Jeff F

TI__Expert 3470 points

How long is the detection time? I didn't see it in the datasheet.

0 Jeff F over 7 years ago in reply to Chuchen Wang

TI__Guru**** 166006 points

BC1.2 spec is 900ms max.

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BQ24295: Input Current Limit