BQ25710: Input current limit during REGN drop mode

Tamio Yokokura

Part Number: BQ25710

According to my evaluation, the actual input current limit is lower than the setting value if REGN in during the drop mode.

- Setting value = 3.25A

- Actual value = 2.8A

The condition is VBUS=5V, CELL_BATPRESZ=2-cells, MinSystemVoltage=6.144V(Default and without BatteryPack.

If VBUS or MinSystemVoltage >7V, the actual input current limit is set to the expected value.

The input current limit is affected by REGN voltage because the the internal ADC doesn't use the ratio metric.

Is my thought correct?

If YES, can you share the data of the actual input current limit during REGN drop mode when the setting value is 3250mA?

Thanks

Tamio

over 6 years ago

0 Joel Hernandez II over 6 years ago

TI__Mastermind 25800 points

Hey Tamio,

The cause of this is likely the ILIM_HIZ pin voltage decreases.

On the EVM, the ILIM_HIZ resistor divider is pulled up to VDDA, whose voltage is derived from the REGN voltage.

When REGN is in drop out, the effective voltage on ILIM_HIZ also drops. Please disable the EXT_ILIM bit in ChargeOption2 and see if the behavior persists.

Regards,

Joel H

0 Tamio Yokokura over 6 years ago in reply to Joel Hernandez II

TI__Expert 3960 points

Hi, Joel,

Thank you for your advice.

I will confirm if ILIM performance is improved by EXT_ILIM setting. next Monday.

I already confirmed that ILIM performance was improved by EN_ILIM=Disable.

Thanks

Tamio

0 Joel Hernandez II over 6 years ago in reply to Tamio Yokokura

TI__Mastermind 25800 points

No problem Tamio.

Let me know what you find.

Regards,

Joel H

0 Tamio Yokokura over 6 years ago in reply to Joel Hernandez II

TI__Expert 3960 points

Hi, Joel,

I confirmed that the input current limit at VBUS=5V was improved by setting REG0x31(ChargeOption2) [7] (EN_EXTILIM)=0b (Input current limit is set by REG0x3F).

Thanks

Tamio

Power management

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BQ25710: Input current limit during REGN drop mode