Rapidly turning on/off a 6V power source

Hello,

I'm working on a project where I want to use an Arduino board to act as a switch for a 6V 500mA power source which is connected to another device. Basically, I just want to be to open and close the 6V circuit via the output of one of Arduino's digital pin.

I have very low latency constraints though: Ideally, it shouldn't take more than a couple of uSeconds (not milliseconds) to turn the 6V circuit on or off.

I'm confident with the software part, but not the hardware. What type of circuit should I use to accomplish this. I have looked at relays (latency too high, usually in the millisecond range), optocouplers and thyristors, but I can't seem to figure it out (my knowledge of electronics is very limited).

I'd appreciate any pointers. Thanks in advance!

You should be able to achieve high-speed switching with a MOSFET.

It depends on if you want to source or sink the current you are switching. I assume you want to source it. In that case you will need p-channel mosfets like the ones I used in this LED matrix project to turn on the rows:- http://www.thebox.myzen.co.uk/Hardware/Mini_Monome.html

Here’s my circuit concept for what you want to do:

Generally, a high-side driver circuit is what you need. They have these in a single chip, like this one:

http://www.st.com/stonline/products/literature/ds/10891.pdf

It's kind of like the above circuit, all-in-one, but with built-in overcurrent protection and a few other things.

-Paul