Other Parts Discussed in Thread: TPD1S414
Does the HD3SS3220 use VDD5 supply for anything other than VCONN? If a customer is not interested in supporting active cables on an UFP, can VDD5 be left unpowered? The question results from the following dialog:
HD3SS3220 VDD is only rated to max 6V, but we could see up to 6.4V (we’re using the TPD1S414 VBUS protection chip now). I do not have 5V anywhere else on the system. Can TI give some guidance as to whether I can safety connect VDD5 to VBUS that may see a fault condition of 6.4V? I could use a divider, but the lowest VBUS level is 4V, and VDD has a min of 4.5V (which is also problem connecting to VBUS in general – not sure if that’s a problem either). I really want to avoid adding a 5V supply for something that I’m not really even using.
Also I have a question on the VBUS_DET Pin. This pin is listed as the “5-28V VBUS Input Voltage. One 900k resistor required between system VBUS and VBUS_DET pin” which makes sense. Then later in the datasheet: VBUS_DET: -0.3V min, 4V max and internal pull-down of 95k, which also makes sense as the voltage divider will always bring VBUS down to below 4V on VBUS_DET. However then I see V(BUS_THR) for VBUS_DET is 2.95V to 3.8V. With the resistor divider, I would think VBUS_DET would never actually see 2.95V, and for VBUS of 5V it would see only about half a volt. Am I missing something about the VBUS threshold voltage spec? Seems like it should be a lot lower?
