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| LM317 control by PWM |
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| 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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