Digital switch

Big_Valven · Joined: 26 Jun 2007 Posts: 24

Hi all,
I am using a MEGA8 and need to control 4 different data lines, a quad bilateral switch is what I am looking for but I need one that uses 3.3v TTL control, and the big crunch is I need to switch a maximum of 12v at 300ma (peak current). Is there anything people know of that will do the job? I am looking at something like a MAX4066 but I cant find any devices with current specifications. I want to keep the circuit as simple and compact as possible hence my desire to have one chip to do the job.

thanks.

Big_Valven · Joined: 26 Jun 2007 Posts: 24

*nudge* anyone?

lpa · Joined: 12 Dec 2006 Posts: 27 Location: Oreokastro, Greece

I think that you are asking for too much power.

300ma X 12V X 4 switches = 14.4 VA = 14.4 W

That is too much power to control from a single device.

You may use 4 solid state relays instead : http://www.futurlec.com/RelSS.shtml

PatM · Joined: 25 Oct 2004 Posts: 104

What about the ULN2803? It handles 500mA @ 50V DC so 300mA @ 12V shouldn't be a big problem.

While it is listed as a 5V device it should work at 3.3V also. Looking at the datasheet it appears to be fully on somewhere around 2.7V.

Of course, this chip is an open collector (sinks to ground) so you would basically have power on whatever you are switching at all times but cut off the ground to turn it off.