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TPD4S014 on the Host ??

Jonathan Jank
Intellectual 1045 points
Other Parts Discussed in Thread: TPD4S014

I’m looking at TPD4S014 and thinking that it may work.  But, I am confused by the typical application drawings in the datasheet.

 

Our situation is we want to have a USB host port on our product.  It is host-only for this design.  I think we can use a standard USB switch with current limit  (but normally are not over-voltage tolerant), and then between that and the USB connector, we can use a TPD4S014 to provide the over-voltage and ESD protection.

 

In the case of a fault, we could have 5V on the internal side applied to VBUSOUT and up to 28V applied to the external side (VBUS), and we would like the TPD4S014 to switch off then and protect our product.

 

Is figure 12 also valid for a USB Host port?  In our case, the battery charger block would be replaced by our 5V power supply in combination with a USB power switch with integral current limit.  In the case when there is no fault, current would flow from the VBUSOUT pin to the VBUS pin, which seems like it might be backwards of what was intended.  The datasheet really doesn’t talk about Host mode at all as far as I can tell, but isn’t a charger port usually a host port?  Figure 16 confuses me even more because of the placement of the current limit switch.

 

It seems like it will work, but I am so confused by the diagrams that it leaves me with some questions.  Can you verify that it will work as I described?

thanks!

  • 0
    TI__Genius 12190 points
    Jonathan,

    With TPD4S014, due to the body diode of the nFET switch, if there is a short to ground on VBUS the system is expected to limit the current to VBUSOUT. Yes, a charger port can be a host, but a charger port may also be a stand alone charger, so that is is not a host.

    Figure 12 can be adapted to a host with a 5V supply where the battery charger is. You will need to have a current limiter to protect against a short on VBUS.

    Figure 16 shows how the TPD4S014 works with a current-limit protected OTG system.

    Regards,