BQ24090: verify the charging circuit ,When i implement the design their is humming sound from IC

anusha M U

Other Parts Discussed in Thread: BQ24090

his schematic was verified by forum. But the physical board design has some issue . Its making the humming sound from the charge IC

Few this thing we absorbed while testing.

when the sound absorbed above 4.67 above, and above 5.18V the humming stops.
Input Voltage @ Vin pin of bq24090 will 4.8 and 4.67 as the input voltage vary from 4.9 to 8.8
with input voltage 4.67,4.8 and 4.90 output voltage is not reaching up-to 4.2.

Th following are few design change in with schematic

RISET IS 1K Draw 0.55A
Instead of Nchannel MOSFET I M USING P channel Mosfet with BJT to gate control from the controller.

Please refer the attachment below for the schematic.

Please help me understand the issue, and help me solve it. Please revert us as soon as soon possible we have on the priority. Please revert for further quires.

over 6 years ago

0 Bill Johns over 6 years ago

TI__Guru 69216 points

Hello
I have downloaded the schematic and removed it from the post.
The noise may be caused by the unit turning on and off due to OVP. With input voltage above 6.6V the unit will turn output off.
Do you have a scope capture of the output voltage and current?

0 anusha M U over 6 years ago in reply to Bill Johns

Intellectual 275 points

Hi Bill,

Thanks for the reply....

The input voltage never exceed 4.9....

Yes I checked it via multimeter the voltage is never reached 4.2 it was always below 4.

Yes made some provision to check the output current and is. About .55 Amps as per the calculation.

Please help me to find the solution for the chartering of PCB.

Please revert asap

0 Bill Johns over 6 years ago in reply to anusha M U

TI__Guru 69216 points

The humming sound is probably from an input or output capacitor and would be due to changing voltage on the cap. Can you check the capacitor voltage at in IN and OUT, should be a DC level with no ripple.

0 Bill Johns over 6 years ago in reply to anusha M U

TI__Guru 69216 points

Output capacitor C2 is isolated from OUT by a D3 and Q2, this could cause stability issues with the regulator circuit. Can you test with 1uF cap located near OUT.

0 anusha M U over 6 years ago in reply to Bill Johns

Intellectual 275 points

Thanks Bill

I ll check that

And one more quire regarding the out voltage, as i said in my previous quires voltage is not reaching the above 4.2? can you please help me with that?

0 Bill Johns over 6 years ago in reply to anusha M U

TI__Guru 69216 points

Any update on this problem?
"Voltage is not reaching 4.2V" -- Bill J -- If the capacitor on OUT is causing stability problems for the current regulator in CC mode or voltage regulator in CV mode it is very possible output will not reach 4.2V.

0 anusha M U over 6 years ago in reply to Bill Johns

Intellectual 275 points

Hey bill

sorry for the late reply

yes, I have tried your suggestion still I can hear the noise.

But I added an extra 1uf capacitor at the output pin noise reduced. But again I could hear the noise from 4.4 to 4.6v input voltage to the battery.

Is there any chance of increasing the value of the decoupling capacitor at the input and output IC? Please verify on this?

My question is, this due to the mosfet at the input? Mofset does give accurate DC output always added with noise?

Please help me with this...

0 Bill Johns over 6 years ago in reply to anusha M U

TI__Guru 69216 points

Hi --- Sorry for the late reply
Adding decoupling capacitor is not a problem.
If the MOSFET on the input in turning on or off that could be a noise source.

This is very unusual.

0 anusha M U over 6 years ago in reply to Bill Johns

Intellectual 275 points

As u seen my the humming sound is stopped as I added extra capacitor at the output charger is not able charge even when the battery voltage is 3.8.... please help with this.

0 Bill Johns over 6 years ago in reply to anusha M U

TI__Guru 69216 points

Working this problem off line

Power management

Power management forum

BQ24090: verify the charging circuit ,When i implement the design their is humming sound from IC