simple current control circuit

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judehue

Joined Apr 20, 2010
8
Does anyone have any ideas for a relatively simple circuit that could take 0-3.3v input and drive 0 to 1.5 Amps into a solenoid with current feedback
 

SgtWookie

Joined Jul 17, 2007
22,230
See the attached.

The curved line (green trace) shows the power dissipation in the MOSFET; it peaks when current through the load (your solenoid) is about 3/4A. You will need to use a heat sink on the MOSFET.
The red trace is the input voltage (0v-3.3v)
The blue trace is the current through the load (0A-1.5A)

This is presuming that your supply is 9v; a minimum of 8.5v is required. If your supply voltage is higher, power dissipation in the MOSFET will be substantially higher.

If you're going to use this in an automotive application, you'll need some way to provide clean power.
 

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SgtWookie

Joined Jul 17, 2007
22,230
You could use the same schematic with an IRFZ10.
But, sense resistor goes between the source and ground. Otherwise, it gets to be a hassle to determine the current. Having Rsense connected right to ground makes it easy.

One thing I omitted was a reverse-EMF protection diode across the load. You should include one. Even a 1N4004 would work. Connect cathode to V+, anode to the drain.
 
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