BQ25792: BQ25792 SDRV

SWENGWOO LEE

Part Number: BQ25792
Other Parts Discussed in Thread: TPS25750

BQ25792 There is something strange in operation, so please inquire.

I am using a SHIP FET configuration.

However, if the SHIP FET is used and the BATTERY is connected, the SDRV voltage is output abnormally.

Also, when I connect the adapter, it doesn't recognize it.

However, when the USB type c adapter is connected, If I remove the battery and plug it back in, it works normally.

The SDRV pin voltage is also output normally.

Can you tell me why?


<Abnormal SDRV PIN Voltage Output>




<Normal SDRV PIN Voltage Output>

over 1 year ago

+1 Jeff F over 1 year ago

TI__Guru*** 143870 points

Hi Swengwoo,

The SDRV pin is the output to a charge pump that is intended only to drive capacitance at the gate of a FET. When battery only is connected, it turns on and off at a fixed duty cycle so simply adding a 10Megohm scope probe is too much load and it will collpase the output. If VBUS is attached, the SDRV pin can drive slightly more power. I recommend using either a powered, JFET scope probe with high impedance or a DMM set to 1Gohm impedance.

I do not understand your question about attaching the adapter. If you connect a USB BC1.2 compatible adapter or many legacy HVDC adapters to VUBS and D+/D- lines, the converter should recognize them for setting IINDPM. The converter does not have CC1/CC2 lines so it cannot recognize a USB type C adapter but will default to unknown adapter and set IINDPM to the highest setting.

Regards,
Jeff

0 SWENGWOO LEE over 1 year ago in reply to Jeff F

Intellectual 270 points

Thank you for answer.

When a fixed duty cycle is output from the SDRV pin, the USB C Type is not recognized.

Is there a way to make the SDRV voltage come out normally when only the battery is connected?

0 Jeff F over 1 year ago in reply to SWENGWOO LEE

TI__Guru*** 143870 points

HI Swengwoo,

I do not expect USB Type C to be recognized ever since the charge has no CCx lines. There is no way to change the SDRV voltage output.

Regards,

Jeff

0 SWENGWOO LEE over 1 year ago in reply to Jeff F

Intellectual 270 points

I'll ask the question again.

If only the battery is connected to the BQ25792 and VBUS is input, it will not charge.


However, if the battery is removed and reconnected while the battery and VBUS are input, it will be charged.

Can you tell me why?

0 SWENGWOO LEE over 1 year ago in reply to SWENGWOO LEE

Intellectual 270 points

8400.BQ25792.pdf

The circuit is also attached.

+1 Jeff F over 1 year ago in reply to SWENGWOO LEE

TI__Guru*** 143870 points

Hi Swengwoo,

I do not see any issues with the charger schematic. The TPS25750 is handling the communication with the USB port and also communicating with the charger. I will send this over to the TPS25750 team.

Regards,

Jeff

0 SWENGWOO LEE over 1 year ago in reply to Jeff F

Intellectual 270 points

Thank you

Power management

Power management forum

BQ25792: BQ25792 SDRV