BQ25606: When charging at 5V it will always charge at around 500mA.

SANGCHUL KIM

Part Number: BQ25606

Tool/software:

hello
I am currently testing the circuit using the BQ25606.
Basic charging and discharging operations work well.
The oscilloscope waveform looks good too.

1. USB D+/D- is not connected.
2. ILIM is set to 240Ω.
3. ICHAG is set to 220Ω.

The problem is that when 5V is input to the power supply, the charging current is limited to about 500mA.

I adjusted the power supply and got the following results:

0.50A@5V
1.43A@6V
2.13A@7V
1.98A@8V
1.52A@9V
1.31A@10V
1.14A@11V
1.02A@12V

To further verify the circuit, we changed the ILIM to 5000Ω and found that it was limited to 0.1A across all voltage ranges.

I believe that the measured current value in some sections may differ from the set value.

If I shorted D+,D- of the BQ25606, the result will be as shown in the current table above.

No matter what method you use, the charging current will not increase at 5V.

BQ25606_circuit.pdf

2 months ago

0 Michael Emanuel35 2 months ago

TI__Mastermind 33765 points

Hello,

My schematic review is as follows:

1. The required 10 uF BAT capacitance does not appear to be present.

Please add this capacitor as this is required.

Can you please measure the VBUS pin at these specific operating voltages? I am wondering if you are hitting the input voltage limit of 4.3 V.

Regards,

Mike Emanuel

0 SANGCHUL KIM 2 months ago in reply to Michael Emanuel35

Prodigy 10 points

thank you your reply

1. already added. (C14 is close to the battery.)

Isn't it VBAT and not VBUS?

VBAT is 3.8V, VBUS is 4.8V

Regards

0 Michael Emanuel35 2 months ago in reply to SANGCHUL KIM

TI__Mastermind 33765 points

Hello,

That is the issue I believe. We explicitly state in the pin configuration, "Connect a 10-µF capacitor closely to the BAT pin". It does no good to decouple the battery with a 10 uF as the battery already has large effective capacitance. The BAT pin of the charger needs to be decoupled.

Regards,

Mike Emanuel

0 SANGCHUL KIM 2 months ago in reply to Michael Emanuel35

Prodigy 10 points

Hello.

I've already tried attaching and detaching 10uF. However, it has no effect.

Regards,

0 Michael Emanuel35 2 months ago in reply to SANGCHUL KIM

TI__Mastermind 33765 points

Hello,

Can you try and measure the ILIM and ICHG pin resistance to GND when no power is on to the board? Is this happening to multiple boards? Have you performed an ABA test? Was the VBUS measurement done at the pin? What does VBUS look like across the other values in the table?

Regards,

Mike Emanuel

0 SANGCHUL KIM 2 months ago in reply to Michael Emanuel35

Prodigy 10 points

Hello,

I purchased a BQ25606 EVM.

I will ask again after the comparative test with EVM.

Thank you for your continued interest.

0 Michael Emanuel35 2 months ago in reply to SANGCHUL KIM

TI__Mastermind 33765 points

I await your feedback.

0 SANGCHUL KIM 1 month ago in reply to Michael Emanuel35

Prodigy 10 points

I received the EVM board and tested it.
However, the results are almost identical to the table above. (battery voltage : 3.8V )

It seems that 2A charging is not possible at 5V.

It appears that the 2A specification can only be met using high voltage charging. (7v above)

However, looking at DatsSheet <Figure 8-1>, I do not understand this situation.

Based on my analysis, I would like to know your opinion.

Regards,

sangchul

0 Michael Emanuel35 1 month ago in reply to SANGCHUL KIM

TI__Mastermind 33765 points

Hi Sangchul,

Please advise on the VBUS pin measurement of TP1 when this is happening. If you attach an adapter with high input cable resistance the adapter may read 5 V with the VBUS pin of the charger actually being in VINDPM. Can you verify the ILIM/ICHG resistance to GND when the device is powered down? Have you tried adjusting the R10/R11 potentiometers on the EVM? Some level of DPM is being hit, whether it is input voltage DPM or input current DPM. Please provide the requested information.

Regards,

Mike Emanuel

0 SANGCHUL KIM 1 month ago in reply to Michael Emanuel35

Prodigy 10 points

--> Power voltage: 8.5V, measurement voltage: 5V

--> ILIM : 215, ICHAG : 220

I found out what the TP1 measurement means.

It was found that there was a large difference between the power supply voltage and the measured voltage.
But this is the first time I have experienced such a difference.
How is there such a big difference? I don't quite understand.

Does this mean I need to use a higher voltage due to the voltage drop?

0 Michael Emanuel35 1 month ago in reply to SANGCHUL KIM

TI__Mastermind 33765 points

Hello,

What this means is your input connection has high input resistance. Enough to cause a 3.5 V voltage drop. Please reduce the input resistance to the charger. You should not solve this problem by just adding more voltage, the input resistance is the thing to fix.

Regards,

Mike Emanuel

0 SANGCHUL KIM 1 month ago in reply to Michael Emanuel35

Prodigy 10 points

hello,

I'm currently testing with a desktop power supply and am getting the same results using other adapters. I think the maximum supply current for these is sufficient. Ultimately, end users will use this product through adapters. This causes the end user to think that the product is charging slowly.
What power supply do you use when testing evm on Ti?

regard,

sangchul

0 Ning T 1 month ago in reply to SANGCHUL KIM

TI__Guru 50191 points

Hi Sangchul,

Any adapter or lab power suppy is fine. The key is the VBUS pin voltage.

Thanks,

Ning.

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BQ25606: When charging at 5V it will always charge at around 500mA.