Enable/Disable USB port using MOSFETs

[Niall Murphy]

I need to simulate plugging and unplugging a USB device. So instead of physically disconnecting the USB cable I want to use something to open the four lines. It miht be sufficient to do the 2 signal lines - I am not sure.

I will be using a GPIO pin from a Raspberry Pi to enable/disable

My first thought is that the control line could drive the gate of a MOSFET and the source of the MOSFET is one of the pins of the USB port.

I have seen optoisolator boards and I could try using one of those, but they seem pricey and I do not need the optoisolation - Apart from my circuit to turn the USB off, the other device connected is an off-the-shelf headset and I do not exect that to damage the USB port.

Is there some other component I could consider here. If MOSFETs are the way to go any tips on selecting the specific MOSFET that would work would be appreciated. The USB traffic will be fast but the gate only gets switched every few seconds.
   
  regards,
           Niall Murphy

[abyrvalg]

What kind of device is it? In most cases it will be enough to switch VBUS line only (an easy task - single MOSFET), but for some kinds of self powered devices w/o VBUS detection it can be a bit tricky.

[mazurov]

You can use a single P-type MOSFET, look here for details -> https://www.circuitsathome.com/camera-control/simulating-cable-disconnect-on-usb-host-shield-2-0  However, it is better to use a dedicated switch, look here for details -> https://www.circuitsathome.com/mcu/vbus-power-control-on-usb-host-shield

[Niall Murphy]

The devices are headsets, so they are not self powered, so it sounds like controlling VBUS with a MOSFET will be sufficient. The links in the second post were very useful. Thank you mazurov.

Now I just need to get soldering!
   Niall

[sacherjj]

Also be aware that there are dedicated USB switching chips for low loss enabling and disabling of USB power, if you have trouble with a dedicated PMOS setup.  Do a search for high side power switch.

[mazurov]

The MIC2004 has very useful feature - when turned off it shorts the output to the ground draining whatever decoupling capacitors may be present on the VBUS on either side of the USB connector. Other "dedicated USB" switches are not that different from P-MOSFETs.