BQ24392: CHG_DET output is high even if DPDM are open and vbus is >3.5V

Krunal K

Intellectual 280 points

Part Number: BQ24392

Hello,

I am using BQ24392RSER for the charger detection application. This IC is working fine except for following scenario,

VBUS is 5V,

DP and DM (pin #7 and 8) are open.

Pin 2 and 3 are connected with the MCU DP and DM.

I have used boost circuit which is generating 5V output and connected with VBUS of this IC. Now problem is that, when Boost circuit is ON, then this IC is giving indication of charger insertion. Hover there is nothing at input, i.e at pin #7 and #8.

So I am not getting condition where VBUS>3.5V, DP-DM are Open and CHG_DET output = low as mentioned in detection table-1.

Can anyone please help me on this. Please find attached image for circuit and table.

over 7 years ago

0 JMMN over 7 years ago

TI__Guru 60870 points

Hi Krunal,

Can you put scope probes on DP and DM? If there is any kind of loading on those pins the BQ24392 may interpret as a charging port connection. Can you provide the schematic from the BQ24392 to the connector?

Regards,
JMMN

0 Krunal K over 7 years ago in reply to JMMN

Intellectual 280 points

Thank for the response.

I probed DP and DM and both are at 0V. Please find updated schematic.

Then I removed power and measured resistance between DP/DM to GND it is >200K.

0 JMMN over 7 years ago in reply to Krunal K

TI__Guru 60870 points

Hi Krunal,

If the DP/DM lines are unconnected, the resistance to ground should be at least 500K. A resistance to ground of ~200K will be enough for the BQ24392 to think there is something connected to the lines.

Regards,
JMMN

0 Krunal K over 7 years ago in reply to JMMN

Intellectual 280 points

When DP and DM are unconnected, resistance to ground is nearly 600K. I tried replacing IC and removed the resistors as well but same behavior so I am not sure where is the exact problem. I am struggling since last two week.

It would be really helpful if you guide me, do you see any problem in diode circuitry or 3V circuitry?

0 Krunal K over 7 years ago in reply to Krunal K

Intellectual 280 points

It was datasheet problem TI has changed diode position in latest datasheet, which fixed my problem.
Thanks for the support.

Interface

Interface forum

BQ24392: CHG_DET output is high even if DPDM are open and vbus is >3.5V