# Controlling USB connections using a BeagleBone

Hi,

I'm trying to prototype an automated testing solution to plug in and unplug
USB devices using software control. At a very high level, the system would
look like this:

why not try to use GATE like 4053 - SPDT

Quoting fanfan <fkpwolf@gmail.com>:

why not try to use GATE like 4053 - SPDT

Because its resistance is too high for this job.

Dave

Why not MOSFET? Rdson can be quite low… And power consumption is not very high. Does the Rdson (can be quite low) distort the data lines?

2012/5/18 dave higton <davehigton@dsl.pipex.com>

Quoting E V <eviala.es@gmail.com>:

Why not MOSFET? Rdson can be quite low... And power consumption is not very
high. Does the Rdson (can be quite low) distort the data lines?

If you look at the USB spec, the signal levels on the two lines are
quite tightly defined, and the bus is terminated. The resistances
you can expect from those families of analogue switch are enough to
change the signal levels quite a lot, and put them out of spec.

MOSFETs are a possibility, but you have to remember that a discrete
MOSFET normally has a diode between source and drain, so it may not
behave quite the way you expect. The diode may or may not be shown
explicitly in the symbol in the data sheet, but it normally exists.

Dave