I have designed a circuit using a LM317 to provide a 13 V voltage rail. The Vin is 24 V. I have voltage voltage divider networks which supply different voltages to a logic comparator which is connected to the Vin. From this voltage regulator I am simulating a Hall sensor and hence have added a potentiometer. The signal is sent to the same comparator mentioned above. (The comparator is comparing voltage levels from the voltage divider network with the Hall sensor.) The circuit also has a 5 V voltage regulator which is supplying its voltage rail to a few more components.
I noticed that the voltage output from the LM317 fluctuates by about 30 mV depending on the load I have set using the potentiometer. Because of this, the output from the voltage divider network is also fluctuating. This causes the voltage levels to change and hence get a undesired output from the comparator.
My question is:
- Is it normal for the LM317 voltage output to fluctuate by 30 mV?
- If this is not normal, how can I fix this issue? I read that if the load output from the LM317 is not much, then there is a chance that the output voltage may fluctuate (this maybe due to the Iadj current). My guess is it might because of this issue, and connecting the 5 V voltage regulator to the LM317 might solve this issue, but I am not sure.
Edit: I haven't updated the schematics. I changed the resistor values from 5k6, 44k2 and 750R → 220R, 1960R and 100R, respectively.