BQ24192I: Input current is large without battery

user6074007

Part Number: BQ24192I

Hi Jeff,

As we have discussed here

https://e2e.ti.com/support/power-management/f/196/t/845657

Improper values of switching inductor and output capacitors will cause large input current of about 30mA when there is no battery being charged.

As the datasheet says, To get good loop stability, the resonant frequency of the output inductor and output capacitor should be designed between 15 kHz and 25 kHz. With 2.2-µH inductor, the typical output capacitor value is 20 µF.

Now in my design, I use 1uH+44uF, but sometimes the current is about 30mA, could you help to investigate further to explain such situation?

Thanks.

over 5 years ago

0 Ning T over 5 years ago

TI__Guru 57321 points

Hi,

We are checking and will get back to you.

Thanks,

Ning.

0 Ning T over 5 years ago in reply to Ning T

TI__Guru 57321 points

Hi,

The device still tries to charge even if the battery is absent (i.e. VBAT pin open) . Please disable charge, then the VBUS current should be much lower.

Thanks,

Ning.

0 user6074007 over 5 years ago in reply to Ning T

Prodigy 130 points

Ning,

Actually, I've found this issue when the chip is disable, that meas /CE pin is high.

Wolf

0 Ning T over 5 years ago in reply to user6074007

TI__Guru 57321 points

Wolf,

When /CE is high, what are the VSYS and ISYS? Please provide all register values under the condition.

Thanks,

Ning.

0 user6074007 over 5 years ago in reply to Ning T

Prodigy 130 points

Hi Ning,

We don't connect any load to the VSYS pin, so the current of VSYS is 0mA.

After powered up, all the register settings are:

reg[00]=0x3d

reg[01]=0x1b

reg[02]=0x00

reg[03]=0x00

reg[04]=0xb2

reg[05]=0x8a

reg[06]=0x03

reg[07]=0x4b

reg[08]=0x85

reg[09]=0x05

reg[0a]=0x1b

I believe it's easy for you to reproduce such issue in the lab.

0 user6074007 over 5 years ago in reply to user6074007

Prodigy 130 points

By the way, maybe you need cycle the power several times to catch such situation, because it doesn't occur every time.

0 Ning T over 5 years ago in reply to user6074007

TI__Guru 57321 points

Hi,

I was unable to duplicate the 30mA input current you described on the BQ24192I EVM. Your GUI shows NTC "both cold", so charge is disabled anyway. Please double check your board.

Thanks,

Ning

0 user6074007 over 5 years ago in reply to Ning T

Prodigy 130 points

Hi,

It shows "both cold", because I don't put the battery in and thus NTC is not connected. If you change the output capacitor to 10uF, it's easier to duplicate it.

Wolf

0 Ning T over 5 years ago in reply to user6074007

TI__Guru 57321 points

Wolf,

Still unable to duplicate the behavior you observed.

Thanks,

Ning.

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BQ24192I: Input current is large without battery