TUSB320: CC output failing.

Hi,

could you help me understand your application? Is TUSB320 in DFP mode. What is the steady state voltage your see?

Default mode. Failed devices read 1.4V steady state. Working devices output a 15hz square wave 5v peak. What is the square wave's purpose?

Hi,

The square wave you see is actually TUSB320 trying to advertise either UFP or DFP mode. The default mode is actually Dual Role Port (DRP) mode. The connection is actually detected via CC1 or CC2. ID can be thought of a GPIO (not configurable) that signals when connect is mad in DRP or DFP mode. Could you describe this USB failure more? Does this mean there is no USB enumeration? What device is being used? 

Our device is a mobile computer with exposed pins to the USB interface. Our device is in host mode when connecting to a USB flash drive, and this is when we are experiencing failures. Replacing the controller IC resolves the issue. The CC1 square wave returns and the USB flash drive functionality returns. Is there a way to assign the CC1 as an input until a physical connection is made? I suspect failures occur because CC1 is initially an output and exposed to ESD.

Is there a way to assign the CC1 as an input until a physical connection is made? This will reduce the ESD vulnerability of this port.

Unfortunately, the pin is not configurable in such a manner. Do you have eternal ES on the CC lines? 

What is an eternal ES? Does TI have an application note on how to protect a constant output that is exposed to ESD such as this CC signal?

My apologies for the typo. I meant to ask if there is external ESD in your design. We do not have a specific document on this. Keep in mind that CC1 and CC2 pins are not constant outputs but I/O pin.

Is your question "Is there external ESD protection in the design?" If so, yes. A transient suppressor. I am seeing a constant square wave output on the CC signal. 5V peak, 15Hz. This signal is exposed to the outside world and next to a GND pin. 

HI,

Sorry for late reply. Are you still seeing this issue? The ESD protection may be turning on and causing issues

What issue are you asking about? My original question was "Should the CC1 signal only be active after a connection is detected via the ID pin? If so, is this function user programmable?"

Sorry for the confusion on my part. To answer your question. Yes, CC1 will be active before ID is asserted. ID is asserted on a connection is made and port roles are defined (DRP mode). The TUSB320 ID pin is not user programmable and the function cannot be changed.