BQ25606: Pulsed ICHG

Hirotsugu Kobayashi

Mastermind 9540 points

Part Number: BQ25606

Hi, team.

When the battery voltage reaches VSYS_MIN, the charging current will be pulsed.

Is this going back and forth in supplement mode?

Is there any way to improve it?

The measurement is done by EVM.

bq25606EVM.pptx

Best Regards,

over 5 years ago

0 Ning T over 5 years ago

TI__Guru 57591 points

Hi,

Could you please provide the followings?

What are the test conditions such as VBUS (voltage at VBUS pin), IVBUS, VBAT (voltage at BAT pin), IBAT, VSYS, ISYS when the behavior happens?
What are all the register values when the behavior happens?

Thanks,

Ning.

0 Hirotsugu Kobayashi over 5 years ago in reply to Ning T

Mastermind 9540 points

Hi, Ning.

The VBAT, VSYS, and IBAT waveforms are attached.

ISYS is 0A because only the charging function is used.

VBUS is 12V. ICHG is 2A, ILIM is 3A, Vset is 4.208V.

Best Regards,

0 Hirotsugu Kobayashi over 5 years ago in reply to Hirotsugu Kobayashi

Mastermind 9540 points

Hi, team.

Do you have any updater?
Is it a phenomenon when BATFET switches from LDO mode?

0 Ning T over 5 years ago in reply to Hirotsugu Kobayashi

TI__Guru 57591 points

Hi,

1. Are you testing with real battery or battery simulator?

2. What are all the register values when the behavior happens?

Thanks,

Ning.

0 Hirotsugu Kobayashi over 5 years ago in reply to Ning T

Mastermind 9540 points

Hi, Ning.

1.Used a real battery
I tried 3 kinds of capacities (4900mAh, 18650mAh, 3500mAh), but all had the same phenomenon.

2. Bq25606 is a standalone type, so there is no register.

Best Regards,

0 Ning T over 5 years ago in reply to Hirotsugu Kobayashi

TI__Guru 57591 points

Hi,

It should be related to BATFET transitioning from LDO mode to fully on mode. It usually does not show up when charging real battery with high capacitance.

Please note that this behavior is “cosmetic”, i.e. it won’t affect the battery and charger performances. The battery will be charged as desired.

Thanks,

Ning.

0 Hirotsugu Kobayashi over 5 years ago in reply to Ning T

Mastermind 9540 points

Ning-san,

Is there any countermeasure?
Is it effective to increase the capacity of the BAT terminal or reduce the impedance to the battery?

Bets Regards,

0 Ning T over 5 years ago in reply to Hirotsugu Kobayashi

TI__Guru 57591 points

Hi,

Adding significant capacitance at BAT pin should help.

Thanks,

Ning.

0 Hirotsugu Kobayashi over 5 years ago in reply to Ning T

Mastermind 9540 points

Thank you.

I will try it.

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BQ25606: Pulsed ICHG