BQ25601: Strange current drop for BQ25601 while charging...

Peter Tseng

Mastermind 6470 points

Part Number: BQ25601

Tool/software:

Hi Team,

May I have your help to check the strange current drop as red circled?

It seems not the pre-charge current waveform.

Thanks.

over 1 year ago

0 Michael Emanuel35 over 1 year ago

TI__Mastermind 42665 points

Hello,

Can you please provide a schematic? What are the registers doing at this time? Is there a system load? Can you plot VBUS, IBAT, BAT, and ISYS? Please provide more information.

Regards,

Mike Emanuel

0 Peter Tseng over 1 year ago in reply to Michael Emanuel35

Mastermind 6470 points

Hi SIr,

After checked with customer, the issue occurred after pre-charge finished and changed to CC mode.

there is the current drop problem.

Is there any idea about current drop issue while mode changed?

The waveform already included VBUS, IBAT, BAT. The system load is DSP and working after power on.

Since the customer wants to monitor the total charging cycle, the time scaling is very long(1Ks).

The schematics as attached.

dc354_BQ25601.pdf

0 Michael Emanuel35 over 1 year ago in reply to Peter Tseng

TI__Mastermind 42665 points

Hello,

We require a 10 uF capacitor on BAT pin close to pin.

Unfortunately there is nothing that we can observe at this time scale. Please zoom in on the moment of concern with the requested waveforms so we can further debug.

Regards,

Mike Emanuel

0 Peter Tseng over 1 year ago in reply to Michael Emanuel35

Mastermind 6470 points

Hi Sir,

I already discussed this with customer and asked for the proper time scale waveform.

Please wait and I will update it once got it.

Thanks.

0 Peter Tseng over 1 year ago in reply to Peter Tseng

Mastermind 6470 points

Hi Sir,

The zoom-in captured waveform as below.

BTW, the customer mentioned this is the moment of mode change from pre-charging to normal charing.

Please help to review it again.

Thanks.

0 Michael Emanuel35 over 1 year ago in reply to Peter Tseng

TI__Mastermind 42665 points

Hello,

Unfortunately this shares no new information to me. The time scale is still 1.00 ks/div, just triggered on a later edge. Please zoom in on a meaningful time scale.

Regards,

Mike Emanuel

0 Peter Tseng over 1 year ago in reply to Michael Emanuel35

Mastermind 6470 points

Hi Sir,

Please refer to the below chart!

The mean charging current in this 200sec section is around 713mA then will increase to 724mA.

Why is there a period of lower charging current after the pre-charging change to normal charging mode?

0 Michael Emanuel35 over 1 year ago in reply to Peter Tseng

TI__Mastermind 42665 points

Hello,

What is the minimum system voltage setting threshold set to here? When operating in MINSYS the BATFET operates in linear mode. In other words it is not fully on. This leads to more power dissipated in the BATFET and can cause lower charge current until out of MINSYS and fully on.

Regards,

Mike Emanuel

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BQ25601: Strange current drop for BQ25601 while charging...