TPS22965: TPS22965TDSGTQ1 Leakage Current

Hi Menghai, 

Could you send me a scope shot of this occurrence showing Vin, ON, VOUT, and IOUT?

The VOUT signal should fall when ON drops below 0.5V. Once this threshold is passed, the output should discharge across the QOD resistance. The fall time will be purely based on the output capacitance and how quickly the output loading can pull it down. 

Best Regards, 

Elizabeth 

Dear Expert,

    The scope shot is as following picture, whose yellow line is the ON signal with about 0V, purple line is the VOUT signal with about 0.9V and  blue line is the VIN signal with about 3.3V.

Hi Menghai, 

Could you explain why there is so much ringing on the output? 

We would not expect this behavior to be caused by the device especially due to it's integrated quick output discharge which prevents the output from floating while the switch is disabled

Do you have anything on your output node VDD_TDA4_MCUIO_3V3 which could be pulling the node high?

Best Regards, 

Elizabeth 

Dear Expert,

1. The ringing on the output is because there is some prolem with this channel of scope prober. Now I use another channel to measure as following blue line.

2. The VDD_TDA4_MCUIO_3V3 is used to power other devices and no node to pull up except for itself.

Hi Menghai, 

Could you confirm from your plot Vin is yellow, EN is pink, and Vout is blue?

There are two options here:

• There is some unexpected pullup on the output 
• The device is broken 

To route out whether there is some unexpected pullup on the output, I would recommend putting Vin low and see what you measure on the output when TPS22965 is disabled. If there is voltage on the output, it must be coming from another source. 

Is this failure happening across your boards? If you have a known working board, a broken IC could be the issue. To find out if your device is broken, I would recommend placing a new TPS22965 IC on the board and see if you experience the same issue. 

Best Regards, 

Elizabeth 

Dear Expert,

    Thank you for your reply. I will further check.

Dear Expert,

    Because the Vout on my board is connected directly to a big copper foil I could not isolate this pin from other network. So I am not sure how other network would affect it. And I would follow it in the future.