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USB Hosts Hubs Transceivers

SuSh_1535366
Contributor

Hello,

 

If 3.3V is applied to D+ (or D-) without supplying power to VCC (VCC_D/VCC_A), will the device be damaged?

Please tell me about the downstream and upstream ports respectively.

 

Regards,

Shimamura

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1 Solution
MallikaK_22
Moderator
Moderator

Hi Shimamura,

As you might be knowing, D+ is pulled up to 3.3V. As per USB spec, the voltage source on the pull-up resistor must be derived from or controlled by the power supplied on the USB cable such that when VBUS is removed, the pull-up resistor does not supply current on the data line to which it is attached. So, in absence of VBUS 9VCC), there shouldn't be current on the data lines.

Regards,

Mallika

Mallika

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MallikaK_22
Moderator
Moderator

Hi Shimamura,

As you might be knowing, D+ is pulled up to 3.3V. As per USB spec, the voltage source on the pull-up resistor must be derived from or controlled by the power supplied on the USB cable such that when VBUS is removed, the pull-up resistor does not supply current on the data line to which it is attached. So, in absence of VBUS 9VCC), there shouldn't be current on the data lines.

Regards,

Mallika

Mallika

View solution in original post

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