TS5USBC41: nFLT always active when nOE deasserted

Tom Rice

Part Number: TS5USBC41

Hello,

We've implemented the TS5USBC412 in one of our designs to provide a way to switch the USB data lines on/off, with OVP protection. IN is connected to a host PC, out is connected to a downstream device. The schematic is below:

We've evaluated our first batch of prototypes and almost everything seems to work well. Without an OVP condition, when nOE is driven low, nFLT goes Hi-Z and we can enumerate devices over USB no problem. However, when the nOE pin is driven high (3.3V logic), the nFLT pin seems to always be driven low, even without an OVP condition on the data lines. This happens both with and without downstream USB devices plugged in.

The Function Table doesn't seem to call out any kind of behavior on the nFLT pin:

Is this the expected behavior?

Thanks,
Tom

5 months ago

+1 Nir Gilgur 5 months ago

TI__Mastermind 24525 points

Hello Tom,

Yes, this an expected behavior.
The FLT pin is an active low open drain pin.
It activates when OE is activated as well.
The logic control is tied to the I/Os and the FLT pin.

Thanks,

Nir

0 Tom Rice 5 months ago in reply to Nir Gilgur

Prodigy 20 points

Hi Nir,

Thanks for the reply. I suppose we will then implement our fault LED as active low (nOE OR nFLT).

Would it be possible to note this behavior of the nFLT pin in the datasheet, maybe in the Function Table?

Thanks again,
Tom

Interface

Interface forum

TS5USBC41: nFLT always active when nOE deasserted