TPS254900-Q1: [TPS254900IRVCRQ1] Inquiry about the cause of output drop

MJ Jeon

Genius 5240 points

Part Number: TPS254900-Q1

Hi, TI Experts

This is a problem that occurred during the review due to a bad USB recognition in the customer company.

The level connected to VBUS from the output port (15th, 16th pin) is lowered to 4V.

Even if there is no load on the output port, the output level is 4V.

1. What causes the output level to drop?

2. Is there a problem with the circuit below?

3. If the VBUS level is lowered, does the USB recognition problem occur?

Please confirm.

Thanks.

Regards,

0 Bing Hwang over 1 year ago

Hi MJ,

So with no load, the VBUS also keeps at 4V? Did you check the status of EN pin?

Thanks.

Bing

0 Bing Hwang over 1 year ago in reply to Bing Hwang

And what is the level of input voltage?

Thanks.

Bing

0 MJ Jeon over 1 year ago in reply to Bing Hwang

Genius 5240 points

Hi, Bing Hwang

Sorry for the late reply.

Vin=5V

Symptoms are intermittent.

Vout maintains 4V and EN is operating normally.

Have there been any previous reports of these symptoms?

Are there any predictions about the cause of the symptoms?

Thanks.

Regards,

0 Bing Hwang over 1 year ago in reply to MJ Jeon

Hi MJ,

I didn't see this behaviors before.

If the issue is with fail rate, in what kind of test condition will the issue occur?

And I don't see the complete schematic, where does "5V_USB_HOST_VBUS" net towards as shown below? R5212, where does the PCB layout connected to?

Thanks.

Bing

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