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USB Hosts Hubs Transceivers

KevinBenstead
New Contributor

Hi

I'm designing a USB hub with CY7C65632 in the 28 pin package.

My hub will be self powered.

Each of my downstream ports has a power switch/monitor which will detect an over current on the port and turn off the power to that port.

I can connect the fault outputs to the OVRn# pins of the chip which will inform the hub of the fault condition.

My question is what does the #PWR pin on the device do when one of the ports detects a fault.  I have the GANG pin set to individual mode.

Does the PWR pin  go high when the  a fault is detected on any one of the ports.  If I then use that signal to control the power switch won't that mean it will turn off the power to all the downstream ports?

I understand that if I set the GANG pin to GANG mode only OVR1# is active (the rest are ignored) but what happens in individual mode.

Lastly.  OVRn# pins are listed as having pull ups.  to which supply pin are these pull up resistors connected?

Thanks

Kevin

 

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1 Solution
Sananya_14
Moderator
Moderator

Hi Kevin,

Individual mode would mean that the power is switched on a per port basis so when one of the ports have a OCP fault condition, only that port is disabled. Your implementation is correct if each port has a PWR# pin corresponding to it like we have in the 48-pin package. But in the 28-pin package, since only one PWR# pin is present, it corresponds to Port 1 so it will only be de-asserted when OVR1# is asserted. The other OVR2#, OVR3#, OVR4# pins would indicate OCP fault condition to the hub but it wont cause the hub to toggle the PWR# pin. 

So, the way to implement individual mode power control in the 28-pin package would be through polyfuses as done in the CY4608 DVK.

The internal pullups are connected to 3.3V VCC supply.

Best Regards,

Sananya

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2 Replies
Sananya_14
Moderator
Moderator

Hi Kevin,

Individual mode would mean that the power is switched on a per port basis so when one of the ports have a OCP fault condition, only that port is disabled. Your implementation is correct if each port has a PWR# pin corresponding to it like we have in the 48-pin package. But in the 28-pin package, since only one PWR# pin is present, it corresponds to Port 1 so it will only be de-asserted when OVR1# is asserted. The other OVR2#, OVR3#, OVR4# pins would indicate OCP fault condition to the hub but it wont cause the hub to toggle the PWR# pin. 

So, the way to implement individual mode power control in the 28-pin package would be through polyfuses as done in the CY4608 DVK.

The internal pullups are connected to 3.3V VCC supply.

Best Regards,

Sananya

View solution in original post

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KevinBenstead
New Contributor

Hi Sanayana

Thanks for your reply.

That information is most useful.

I was confused by the CY4608DVK circuit as it has both poly fuses and AIC1526-0 power switches.

Thanks again

 

 

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