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LM317 control by PWM
tzc:
I am trying to adjust the output of the LM317 by using PWM of microcontroller but I cant get the aspected result that I want ,even the output of the non inverting operation amplifier is wrong.
It is my schematic diagram is wrong?
please give some recommendation and suggestion.
Thanks.
iMo:
What is the value of RV1?
What is your PWM frequency?
Here is something which may work: https://www.eevblog.com/forum/beginners/pwm-for-lm317-how-to-increase-resolution/msg1809224/#msg1809224
The R6/R7 in my schematics is the feedback from the output of the LM317.
What results you get?
Yansi:
Why would one want to use a LM317 for this task? It is one of the worst choices, if there is an opamp available already.
Beef the opamp outputs with a suitable NPN transisotr and let the opamp deal with the regulation. Then just one NPN more to add current limiting.
Zero999:
What's the PWM voltage?
What's the desired output voltage range?
tzc:
--- Quote from: imo on February 01, 2019, 11:32:17 am ---What is the value of RV1?
What is your PWM frequency?
Here is something which may work: https://www.eevblog.com/forum/beginners/pwm-for-lm317-how-to-increase-resolution/msg1809224/#msg1809224
The R6/R7 in my schematics is the feedback from the output of the LM317.
What results you get?
Thanks for your reply
RV1=10Kohm
PWM frequency= 1KHz
PWM Voltage=0-5V peak-peak
--- End quote ---
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