BQ24610: Charge current problem at 12V input.

O2inSpace

Part Number: BQ24610

Tool/software:

Hello, i designed a charged desk lamp but i have a problem. My circuit doesn't work at 12V. I set the battery charge current to 4A. It charges with 1.2 amps at 12V. I tried to gradually reduce the input voltage. When it reached 6V, I saw 3.9 amps(i measured 0.039V on the 10mohm resistor) but different sounds are coming from the circuit(like saturation sound). I want to charge it with 4 amps at 12V. What am I doing wrong? I added my circuit schematic below.

PCB LAYOUT;

Oscilloscope images;

The signals on the oscilloscope shows the signal coming to the input of the inductor.

12V (1.3A Charge current):

8V (1.3A Charge current):

6V (3.9A Charge current):

Inductor Datasheet;

5 months ago

0 O2inSpace 5 months ago

Prodigy 20 points

I forgot to write. The signal on the oscilloscope shows the signal coming to the input of the inductor.

0 Christian Moyer 5 months ago in reply to O2inSpace

TI__Mastermind 32246 points

Hello O2inSpace,

What is your input voltage?

What is your max battery voltage?

Best Regards,

Christian

0 O2inSpace 5 months ago in reply to Christian Moyer

Prodigy 20 points

Hello Christian,

Input voltage is 12V,

I'm using 5 parallel 18650 li-ion battery. Nominal 3.7V, maksimum charge voltage is 4.2V.

Best regards.

0 O2inSpace 5 months ago

Prodigy 20 points

Is there anyone who can help?

0 Christian Moyer 4 months ago in reply to O2inSpace

TI__Mastermind 32246 points

Hello O2inSpace,

Thank you for your patience. TI was out of office because of holiday.

There is a high ringing noise on the SW signal

Do you see any change if you add a gate reistor 2-10ohm?

Do you see any changes if you add a RC snubber circuit between SW and PGND( 10ohm resistor, 330pF-1nF capacitor)?

Best Regards,

Christian.

0 O2inSpace 4 months ago in reply to Christian Moyer

Prodigy 20 points

Hello Christian,

I addet 6.8 ohm to gate of mosfets and i added the snubber (10 ohm and 470 pF) then i measured the charge current. The charge current increased from 1.2 amps to 2.1 amps. I had set it to 4 amps normally. I measured the inductor input with an oscilloscope, the signal is a little better.

Best regards.

0 Christian Moyer 4 months ago in reply to O2inSpace

TI__Mastermind 32246 points

Hello O2inspace,

O2inSpace said:
I addet 6.8 ohm to gate of mosfets and i added the snubber (10 ohm and 470 pF) then i measured the charge current. The charge current increased from 1.2 amps to 2.1 amps. I had set it to 4 amps normally. I measured the inductor input with an oscilloscope, the signal is a little better.

I think increasing the cap on the snubber circuit should further increase the charge current. My concern is the ringing on the switch node.

Best Regards,

Christian.

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BQ24610: Charge current problem at 12V input.