Can't find the right device to use.. please help?!

Thread Starter


Joined Mar 5, 2008
Hi folks. I am new to the group and I am very happy to have found it. Someone might be able to help me and make a reccomendadtion on what type of device I should use for the following:

I am trying to find a transistor to use as a switch to handle some pretty hefty current and can’t seem to find one. I need to find a way to switch +200VDC at around 3 Amperes, (possibly 5 Amperes surge). I can only drive it with a + 5V TTL 24 mA source or 64 mA ground sink max. I haven’t had any luck finding a PNP transistor that will let me do that. Is there something better then a transistor to use? I don't really want to use a relay because of the reliability of the mechanical contacts at that voltage, and it would be cost prohibitive since I need to build many of these for my project. This is a personal project and is not for profit. If you have any suggestions, I would really appreciate the help. Thanks so much!


Joined May 16, 2005
There are oodles of MOSFET switches able to handle the voltage and current, but the requirement of being driven by TTL is a big challenge. Would you consider driving a transistor or MOSFET driver with the TTL, and in turn driving the MOSFET with the driver or transistor?


Joined Jun 20, 2007
you'd definately have to have a driver in between the ttl and the high voltage/current switching device.

maybe you could drive a darlington from ttl but in essence a darlington is a monolithic device of the above i'd say.