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USB hosts hubs transceivers

TeMa_2997106
Level 6
250 replies posted 250 sign-ins 100 replies posted
Level 6

In CY4609, the supply of VBUS_US is changed from 5V to 2.5V by the resistance voltage divider of R16 and R17.

HX3_VBUS_US_10K.jpg

What is the reason for this? What is R16 needed for?

Thanks,
Tetsuo

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Ajeethkumar
Moderator
Moderator 100 sign-ins 25 solutions authored 5 likes given
Moderator

Hi Tetsuo-san,

The resistors R16 and R17 in CY4609 are connected to the VBUS_US pin, to discharge VBUS faster in case of a disconnection event.

Also, VBUS_US is used for VBUS detection from the US port. VIH of HX3 is 0.7 × VDD_IO = 2.31V. As 2.5V(at VBUS_US pin) is greater than VIH, HX3 would be able to detect VBUS presence with these resistors present.

Thanks,
Ajeeth

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Ajeethkumar
Moderator
Moderator 100 sign-ins 25 solutions authored 5 likes given
Moderator

Hi Tetsuo-san,

The resistors R16 and R17 in CY4609 are connected to the VBUS_US pin, to discharge VBUS faster in case of a disconnection event.

Also, VBUS_US is used for VBUS detection from the US port. VIH of HX3 is 0.7 × VDD_IO = 2.31V. As 2.5V(at VBUS_US pin) is greater than VIH, HX3 would be able to detect VBUS presence with these resistors present.

Thanks,
Ajeeth

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