![]() This cookie is set by GDPR Cookie Consent plugin. These cookies ensure basic functionalities and security features of the website, anonymously. Necessary cookies are absolutely essential for the website to function properly. : CAD Plugins: Current Power Supply Regulator If you plan to use any of these two circuits, design a proper PCB for it, then replace the probe’s ground lead with a ground spring, then you can re-examine the output noises.įigure 4: Oscilloscope capture from the current booster output (read the text) The circuit has been built on the prototyping board and the oscilloscope’s probe ground connection has been made through the ground lead, so these high-frequency noises are normal. Figure 4 shows the output noise/ripple of the MJ2955 current boosting circuit. I intended to measure the possible output ripple of the circuit. I used the Siglent SDS1104X-E oscilloscope that offers a nice low noise front end. You can watch the complete test process in the video, however, I also put an oscilloscope captured image from the circuit output. There is an option to purchase/compare the prices of the original components from authorized distributors as well.įigure 3: Boosting circuit implementation using an MJ2955 To install the libraries, you can either manually download/install the libraries, or directly install them using the provided CAD plugins. If you want to quickly design a PCB layout for the schematics, you can use the free SamacSys component libraries that follow industrial IPC footprint standards. I decided to test the figure 1 (MJ2955 boosting). The schematic diagrams are simple, so I decided to implement them on a prototyping board to test and show the operation. Here 2N3055 plays the role of pass-transistor also.įigure 2: LM317 current boosting circuit using 2N3055 The 10K resistor at the output draws a small amount of current to avoid the floating output and it helps to stabilize the output voltage. Don’t forget to install the transistor on a big heatsink.Ĭurrent Boosting Using an NPN Power Transistor (2N3055)įigure-2 shows the schematic diagram of the circuit. 1000uF, 10uF, and 100nF capacitors have used to reduce noises. As mentioned earlier, the 5K potentiometer defines the output voltage. 1N4007 is a protective diode and 270R resistor provides the necessary ADJ pin’s current. Based on this parameter, the power rate of the resistor must be calculated. The 10R resistor defines the Turn-On time of the pass-transistor and by the way, it defines how much current should passe through the LM317 and MJ2955. This is an adjustable high current regulator circuit that the output voltage can be adjusted using a 5K potentiometer.įigure 1: LM317 current boosting circuit using MJ2955 This problem can be solved using a pass power transistor.Ĭurrent Boosting Using a PNP Power Transistor (MJ2955)įigure-1 shows the schematic diagram of the circuit. This information proves to us that this cheap 3-terminal device is suitable for many applications but it comes with a drawback for power applications and that is the limitation of the regulator’s output current handling (1.5A in the best conditions). Overload protection remains functional even if the ADJUST terminal is disconnected.” It includes current limiting, thermal overload protection, and safe operating area protection. The device features a typical line regulation of 0.01% and a typical load regulation of 0.1%. ![]() It requires only two external resistors to set the output voltage. ![]() In this article, I will discuss two methods of LM317 current boosting, using power PNP and NPN pass transistors.Īccording to the LM317 datasheet: “The LM317 device is an adjustable three-terminal positive-voltage regulator capable of supplying more than 1.5 A over an output-voltage range of 1.25 V to 37 V. However, the chip can deliver currents up to 1.5A which is not enough for some power applications. The output voltage of the regulator can be adjusted from 1.25V to 35V. LM317 is one of the most popular adjustable regulator chips.
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