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I am driving a solenoid with a DRV103 (a driver for inductive loads by TI), but I need to allow more current to flow to the solenoid than the DRV103 can output. Initially, I tried a simple common source amplifier like this:

enter image description here

Ignore the component values, that's just to show topology. I couldn't get that to work though and wasn't seeing any amplification of the original signal. I feel like there's a really simple solution to this problem, but it's bugging me that I can't figure it out. Also, is there anything special I need to take in account when trying to drive an inductive load with a MOSFET?

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What is the purpose of PWM to solenoid? trying to make an linear flip flip? or just burn out your drivers? or trying to make the solenoid quieter? It's just a matter of Ohm's Law. – Tony Stewart Apr 18 '12 at 3:52
In your present circuit, the current will always flow through the coil and the diode, no matter what MOSFET is doing. (How does that feel?) – Nick Alexeev Apr 18 '12 at 4:04
The schematic doesn't bear any relationship to your question – stevenvh Apr 18 '12 at 6:19
@stevenvh, I think that is the heart of the question. It is not functional and to you the schematic makes no sense, but that is because that is what is stopping function. – Kortuk♦ Apr 18 '12 at 6:33

1 Answer

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Connect the diode in parallel with the coil. Leave the anode as is and move the cathode from the battery's neg terminal to the positive terminal.

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