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Low Noise Adjustable Power Supply (30V-4A, CC-CV)

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Power supplies are one of the most popular topics in electronics. There are two major types of regulated power supply: linear and switching. Both power supply types introduce some advantages and disadvantages, however, a linear power supply offers better line and load regulation figures and it handles lower noise at the output, specifically when the power supply is adjustable and the output is under load; although its efficiency is lower than a switching power supply. In this article/video, I introduced an adjustable 30V-4A linear power supply that provides constant voltage and constant current adjustment. The output noise of the power supply is low and has measured using the power analysis feature of the Siglent SDS2102X Plus oscilloscope. All component packages are through-hole, so you don't need any special tool for soldering. Let's get started!

Input Voltage (max): 35V [30V, max-tested]
Output Voltage (min): 1.28V
Output Voltage (max-tested): 27.35V [28.9Vin, no load, 25C]
Output Current: 1.1mA to 4A(max continous)
Output Noise (no load): 6-7mVpp
Output Noise (1A load): 6-7mVpp
Output Noise (2A load): 8-10mVpp



Article: https://www.pcbway.com/blog/technology/30V_4A_Adjustable_Power_Supply__CC_CV_.html
[1]: LM338 datasheet: https://www.mouser.com/datasheet/2/405/lm338-440432.pdf
[2]: IRLZ44 datasheet: https://www.vishay.com/docs/91328/sihlz44.pdf
[3]: LM358 datasheet: https://www.mouser.com/datasheet/2/308/lm358-d-299970.pdf
[4]: 78L09 datasheet: https://www.jameco.com/Jameco/Products/ProdDS/192225.pdf
[5]: LM358 schematic symbol, PCB footprint, 3D model: https://componentsearchengine.com/part-view/LM358N%2FNOPB/Texas%20Instruments
[6]: 78L09 schematic symbol, PCB footprint, 3D model: https://componentsearchengine.com/part-view/MC78L09ACPG/ON%20Semiconductor
[7]: LM338 schematic symbol, PCB footprint, 3D model: https://componentsearchengine.com/part-view/LM338T%2FNOPB/Texas%20Instruments
[8]: IRLZ44 schematic symbol, PCB footprint, 3D model: https://componentsearchengine.com/part-view/IRLZ44NPBF/Infineon
[9]: Electronic designing CAD software plugins: https://www.samacsys.com/library-loader-help
[10]: Altium Designer plugin: https://www.samacsys.com/altium-designer-library-instructions
[11]: Siglent SDS2102x Plus oscilloscope: https://www.siglenteu.com/digital-oscilloscopes/sds2000xp

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A tip: As I mentioned in the video, in the last revision of the PCB board (which is available for you), the distance between electrolytic capacitors and the power resistors has been increased, however, if you still have concerns about this, you can use 470uF-50V capacitors instead of 1000uf-50V capacitors which are smaller in diameter.

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