Kind of a dumb question, but Im making a little gadget that has a connector with a limited number of pins available. I want to have the one pin be "dual-purpose" +12v high side driver OR low-side driver, based on what I configure it as in the Arduino software.
Yes, I realize I can break things if I accidentally set both outputs of the Arduino "high" at the same time, Im not worried about that.
I do not need much current sink/source capability, only 50-70 mA would be plenty.
So basically, when I set pin 1 on the arduino "high" (and pin 2 low)...the circuit outputs +12volts
....and when I set pin 2 on the arduino "high" (and pin 1 low).....the circuit is driven low to ground to act as a low-side-driver.
The circuit needs to be as compact/simple as possible, as space is very limited on the PCB Im going to be using. SOT-23 components at the largest, even smaller would be better....
Here is a picture of basically what Im trying to accomplish.
What you are describing is a half-bridge. There are a few things missing from your diagram needed to make it work.
Since your source voltage is 12v the p channel FET needs 12v at its gate to turn off.. the Arduino can only output 5v so it would not be able to turn off. A transistor would be needed to switch the 12v gate voltage.
The low side can work (as long as you have a logic level FET) from the 5v Arduino out.
Gate resistors and pull-down ( or pullup) resistors are needed for the FETs too.
alka:
What you are describing is a half-bridge. There are a few things missing from your diagram needed to make it work.
Since your source voltage is 12v the p channel FET needs 12v at its gate to turn off.. the Arduino can only output 5v so it would not be able to turn off. A transistor would be needed to switch the 12v gate voltage.
The low side can work (as long as you have a logic level FET) from the 5v Arduino out.
Gate resistors and pull-down ( or pullup) resistors are needed for the FETs too.
Great thanks!
I sort of thought it might be a half-bridge, but all of the half-bridge circuits I could find only used one single output from the Arduino to drive both N-channel and P-channel mosfets.........so I wasnt sure if my "dual input, single general-purpose/reconfigurable-via-software output" setup was different than a half bridge.
That chip would work for maybe up to 100ma or so just fine. On digikey under MOSFET arrays and you can find lots of n-p dual MOSFETs but you get the idea.
Remember although the mosfets are rated up to 20v the gates are rated to 12. Don't try and pull down the top gate to ground to turn on beyond 12v.