BQ25606: Precharge issue.

Sanghyun Chang

Prodigy 60 points

Part Number: BQ25606

Hi everyone!

I designed like a circuit.

Vin : 5V (USB)

Charging Currnet (ICHG) : 1A =K (Rset = 670R)

Input Current Limit : 1.99A (Rlim = 240R)

Battery : 4.2V 3000mAh.

When Battery is discharged about 2.615V, connect external power 5V USB type-C connector.

There is 3 states charging states.

1) 2.615 ~ about 3V : about 4~50mA constant charging about 13 minutes . (No problem)

2) about 3V ~ about 3.23V

- There is any Problem ! ! !

- LED D12(STAT) is blink per 1 sec and takes 2 hours to exit this charging state.

※ Here I checked value

- VBUS : 5.08V.

- VREGN : 5.08V (when fast charging 4.36V downed)

- VTS : 2..94V (I didn't use NTC, I used fixed resitor 10kOhms at J7 connector.)

==> Please suggest me where can I check it?

3) above 3.23V

- charging 1A (No problem)

- state led is no blink, no heat in pcb & battery.

over 4 years ago

0 Sanghyun Chang over 4 years ago

Prodigy 60 points

Oops, I missed circuit.

Thanks lot~!

0 Ning T over 4 years ago in reply to Sanghyun Chang

TI__Guru 57721 points

Hi,

Please visit https://e2e.ti.com/support/power-management/f/196/t/890626 for BQ25606: Schematic Review and PCB Layout Design Tips. Additional Information including FAQs is available http://www.ti.com/lit/an/slva924/slva924.pdf Designing A Standalone Single Cell 3-A Charger with the bq25606.

Please check if STAT pin indicate any faults and debug from there. STAT pin blinks 1Hz when Charge suspend (input overvoltage, TS fault, timer fault or system overvoltage).

Please also check if the input source is over-loaded, either the current exceeds the input current limit or the VBUS pin voltage falls below the input voltage limit.

Thanks,

Ning.

0 Sanghyun Chang over 4 years ago in reply to Ning T

Prodigy 60 points

Dear Ning.

I understand this issue when I read slva924.pdf.

Thanks lots~!

Battery charging mode has 3 state.

2.6 ~ 3.0V : Trickle charging (100mA)

3.0 ~ 3.2V : Precharging ( 5% of ICHG(1A) : In my case 50mA)

3.2~ 4.2 : Fast charging (1A)

In Precharging states, it take much time

It is normal.

So I will apply Undervoltage Lockout circuit to prevent discharging below 3.2V.

Thanks for your comments.

0 Ning T over 4 years ago in reply to Sanghyun Chang

TI__Guru 57721 points

Hi,

It is great that your questions are addressed. The thread is closed.

Thanks,

Ning.

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BQ25606: Precharge issue.