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!