TUSB522P: Differential input absolute maximum ratings when unpowered

Sergio Celiento

Part Number: TUSB522P

Hello

I would like to know if it's possible to apply the USB signals to the differential inputs of the TUSB522P when the device is unpowered without damages.

Thank you very much for your feedback

Sergio

over 5 years ago

0 Malik Barton57 over 5 years ago

TI__Guru 64326 points

Hi Sergio,

In typical applications, when TUSB522P is not powered the RX terminations will be disabled and the USB link will not connect so no USB traffic will be seen by TUSB522P. However if signal is seen TUSB522P, while not powered, has high impedance inputs at the USB receivers. Does this answer your question?

0 Sergio Celiento over 5 years ago in reply to Malik Barton57

Prodigy 40 points

Hi Malik

Thank you for your reply. So you are confirming me that the if the device is unpowered and the the USB signals are applied, then the TUSB522P will be not be damaged in any way?

Thank you very much

Sergio

0 Malik Barton57 over 5 years ago in reply to Sergio Celiento

TI__Guru 64326 points

Hi Sergio,

As I mentioned when powered no USB signals should be transmitted without RX termination. Since TUSB522P is not powered, not terminations are present and "USB signal" should not be present. Are you seeing this in your application or design?

0 Sergio Celiento over 5 years ago in reply to Malik Barton57

Prodigy 40 points

Hi Malik

In our application there is the chance that the usb signals is applied to pins 9 (RX1P) and 8 (RX1N) of TUSB522P also when the device is unpowered. Is this condition allowed or the device will be damaged?

Thank you very much

Sorry if I haven't been so clear in my precedent questions

Sergio

0 Malik Barton57 over 5 years ago in reply to Sergio Celiento

TI__Guru 64326 points

Hi Sergio,

The USB Host should not be transmitting signal in this case since there is not receiver termination, this is a USB spec violation. TUSB522P RX is high impedance when un-powered, if signal is present the will be some leakage current however it should not damage the part. This assumes that this input signal does not violate the Abs Max table listed in the datasheet.

0 Sergio Celiento over 5 years ago in reply to Malik Barton57

Prodigy 40 points

Hi Malik

Thank you for your support. Now it's all clear.

Sergio

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TUSB522P: Differential input absolute maximum ratings when unpowered