BQ24616: Set charge current is not being delivered

sai prakash

Part Number: BQ24616

Tool/software:

Hi,

Thanks in advance,

We have already used BQ24616 in our old previous project where everything works all fine and good. We are using the same design in our new project also. but here the battery is not being charged with the set charge current. everything else other than works all fine and good. The charge current is set of 750mA but the current being delivered is in the range of 290-340 mA. I have attached the calculation values and the schematic for your reference.

can anyone suggest me a solution or let me know where to and what to check.

Regards,

Saiprakash.C.J

8475.schematics.pdf BQ24616.xls

7 months ago

0 Christian Moyer 7 months ago

TI__Mastermind 19810 points

Hello Saiprakash,

What is the measured battery voltage?

What is the measured voltage on the VFB pin?

Best Regards,

Christian.

0 sai prakash 7 months ago in reply to Christian Moyer

Prodigy 60 points

Hi Christian,

Thanks for your reply,

the battery voltage currently it is 16V.

and the voltage at the VFB is 2V.

and the values of R22 and R24 are 680K and 100K.

Regards,

Saipraklash.C.J

0 Christian Moyer 7 months ago in reply to sai prakash

TI__Mastermind 19810 points

Hello Sai,

The programmed charge voltage is 12.3V, but your battery voltage is around 16V?

Have you tried discharging the battery below 11Vand recharging the battery?

What is the charge current at lower battery voltage?

Best Regards,

Christian

0 sai prakash 7 months ago in reply to Christian Moyer

Prodigy 60 points

Hi Christian,

The reason for this is we already have bq24616 working on another project which works at 16.3V, Since it is working there we tried to bench mark it. So the charge voltage in this also is changed to 16.3 for comparing the signals.

will check at lower voltages and let you know.

Regards,

Saiprakash.C.J

0 sai prakash 7 months ago in reply to Christian Moyer

Prodigy 60 points

Hi Christian,

Just for your info,

1) i tried probing my VFB pin on the working and not working board and i am seeing that in the working board the the VFB signal has a flat line and in the not working board there is a 600KHz noise, I have attached an image for your reference. Do you think this is gonna affect my charge current?

2) I tried measuring across the current sense resistor R10 with a multimeter, on the working board it shows 250mV and on non working board it shows 500mV for the same battery.

3) In the not working board what ever charge current i set is getting cut into half for example if i set 750mA only 300-350mA is delivered. So only when i set 1.5A it is delivering 700-750mA.

Regards,

Saiprakash.C.J

0 Christian Moyer 7 months ago in reply to sai prakash

TI__Mastermind 19810 points

Hello Sai,

Is there any difference between the two boards in terms of schematics?

Can you confirm that R10 is 10mohms?

Best Regards,

Christian,

0 sai prakash 7 months ago in reply to Christian Moyer

Prodigy 60 points

Hi Christian ,

No there is no difference in the schematics, it was copied.

yes R10 is 10mohms.

Regards,

Saiprakash.C.J

0 Christian Moyer 7 months ago in reply to sai prakash

TI__Mastermind 19810 points

Hello Sai,

sai prakash said:
yes R10 is 10mohms.

Did you measure 10ohms? Have you tried replacing this sense resistor?

Best Regards,

Christian.

0 sai prakash 7 months ago in reply to Christian Moyer

Prodigy 60 points

Hi Christian,

Good day,

sorry for the late reply,

Yes, i tried replacing as well from a working board.

Nothing changed.

Regards,

Saiprakash.C.J

0 sai prakash 7 months ago in reply to sai prakash

Prodigy 60 points

Dear Christian,

The issue got resolve, the track to R10 sense resistor from inductor L3 to R10 and R10 to J2 was very thin (0.5MM), I had an external wire connecter to it and the problem got resolved.

It was a layout issue.

Regards,

Saiprakash.C.J

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BQ24616: Set charge current is not being delivered