High Side Switching

I am using my 5V Mini Pro Arduino to send a 12v signal to vehicles PCM. I can’t do a Low side switch because I have to activate 12v to the computer. I was able to use a 2n2222 NPN transistor and a A838 PNP transistor to activate the the 12v signal successfully. Attached is the schematic I modeled mine after.

I need to do this across 3 different wires though. So i have 6 transistors and 9 resistors to make this all work.

Is there a IC chip that does what l’ve done here? I am trying to fit this into a very small enclosure with other electronics and am also looking to make around 100 of these, so a smaller and cheaper option is desired.

I am also looking into an opto-isolator/opto-coupler instead of these transistors. Would this be a better route to go?

OehwI.png

You can get by with just one npn transistor per channel

  • resistorvto the base
  • emitter to gnd
  • collector to 12v via a resistor
  • feed to pcm from the collector.

You can buy packages containing 4 or possibly 6 transistors

Are you saying that I have a Pull-up resistor to put 12v to the PCM, then use the arduino to pull the signal to ground? Would this work?

borntoski:
Is there a IC chip that does what l’ve done here? I am trying to fit this into a very small enclosure with other electronics and am also looking to make around 100 of these, so a smaller and cheaper option is desired.

223d03cbc517410e8e319dc12a05ef3f797a941a.png
OK, the chip used to be called a UDN2983, but is now an A2982.

Opto isolators are very flexible tools for this sort of signal switching too.

Historically, you could do this with a Texas Instruments LMD18400.

Data Sheet

However, I think these have gone obsolete.

You can also get high side load switch packages which appear to be appropriatefor this sort of application e.g. :

Yes, assuming the input circuit has a reasonably hi impedance .

hammy:
Yes, assuming the input circuit has a reasonably hi impedance .

Good point. He didn't say what the load is but the 2n3906 he selected is good for 200 mA.
If the load is small, of the order of a few mA, then the open collector solution depicted in post #2 is also appropriate. The logic has to be inverted so switching the transistor ON switches the target device OFF.