LM317 Current Limit not changing in LTspice sim with changes to resistor value

Thread Starter

mike__MecE

Joined Feb 20, 2022
45
I step R5 and scope LM317 out and there is no change. I tried a handful of different LM317 spice models found in various forums.

Background - I am trying to limit the average power dissipation in the solenoid. 9W is 100% duty cycle so this circuit is intended to limit to 9W average, but allow the cap to charge up and deliver over 80W pulses. I believe 3.2 Ohm is the correct value for the LM317 resistor.

The circuit overall seems to be working similarly to as intended, but the LM317 current output is not changing so I cant fine-tune the average power of the solenoid. Its now at 8.35W which is coincidentally pretty close to what I want.ckt2022-03-26.PNG pl35.PNGpulses.PNG
 

Attachments

Top