Electronics > Projects, Designs, and Technical Stuff
LM317 digital control
Maobuff:
--- Quote from: Liv on May 22, 2016, 10:22:24 pm ---Using LM317 beyond its standard features is a bad idea. I recently made a PSU adjustable 0..±15 V and 0..+5 V based on LM317/337. The number of auxiliary parts was larger. In addition, it was necessary to add the supervisor scheme, since the power is turned off at the output there was a voltage surge. If you need a power supply with CC and CV modes, properly do it on discrete components. Here is a good example of a simple power supply with the processor control.
--- End quote ---
Nice PSU there. Actually its ok to use lm317 as CC, there a circuit in datasheet. But its hard to control it digitally.
ZeTeX:
--- Quote from: Maobuff on May 23, 2016, 09:57:04 am ---
--- Quote from: Liv on May 22, 2016, 10:22:24 pm ---Using LM317 beyond its standard features is a bad idea. I recently made a PSU adjustable 0..±15 V and 0..+5 V based on LM317/337. The number of auxiliary parts was larger. In addition, it was necessary to add the supervisor scheme, since the power is turned off at the output there was a voltage surge. If you need a power supply with CC and CV modes, properly do it on discrete components. Here is a good example of a simple power supply with the processor control.
--- End quote ---
Nice PSU there. Actually its ok to use lm317 as CC, there a circuit in datasheet. But its hard to control it digitally.
--- End quote ---
Using LM317 As constant current and other LM317 as CV is using it standard features, they give you a schematic with CC + CV in the datasheet.
ZayneTech:
http://www.circuitstoday.com/few-lm317-voltage-regulator-circuits
Check out this picture
RES:
Another idea.
Zero999:
--- Quote from: ZeTeX on May 23, 2016, 11:46:40 am ---
--- Quote from: Maobuff on May 23, 2016, 09:57:04 am ---
--- Quote from: Liv on May 22, 2016, 10:22:24 pm ---Using LM317 beyond its standard features is a bad idea. I recently made a PSU adjustable 0..±15 V and 0..+5 V based on LM317/337. The number of auxiliary parts was larger. In addition, it was necessary to add the supervisor scheme, since the power is turned off at the output there was a voltage surge. If you need a power supply with CC and CV modes, properly do it on discrete components. Here is a good example of a simple power supply with the processor control.
--- End quote ---
Nice PSU there. Actually its ok to use lm317 as CC, there a circuit in datasheet. But its hard to control it digitally.
--- End quote ---
Using LM317 As constant current and other LM317 as CV is using it standard features, they give you a schematic with CC + CV in the datasheet.
--- End quote ---
Yes that works, but a big downside of using two LM317s in series is the huge drop-out voltage, as they both add together. The CC circuit will need the usual 3V of headroom plus 1.25V, giving 4.25V, plus the CV circuit requiring the usual 3V: a total of 7.25V!
--- Quote from: ZayneTech on February 02, 2019, 10:02:52 pm ---http://www.circuitstoday.com/few-lm317-voltage-regulator-circuits
Check out this picture
--- End quote ---
The base resistors are missing.
It works better with MOSFETs.
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