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Lm317T power supply diagram


Lm317t power supply diagram. Power supply ON lm317. Schemes and calculations

The microcircuit has been a hit among novice radio amateurs for more than a decade due to its simplicity and reliability. Based on this microcircuit, you can assemble an adjustable power supply unit based on LM317, a current stabilizer, an LED driver and other power supplies. This will require several external radio components, for the LM317 the switching circuit works immediately, no configuration is required.

Microcircuits LM317 and LM317T datasheet are completely identical, differ only in the case. There is no difference or difference, not at all.

I also wrote reviews and datasheet for other popular ICs,. With good illustrations, clear and simple diagrams.

  • 1. Characteristics
  • 2. Analogs
  • 3. Typical connection schemes
  • 4. Calculators
  • 5. Connection diagrams
  • 6. Radio constructors
  • 7. Datasheet


The main purpose is to stabilize the positive voltage. The regulation takes place in a linear way, in contrast to pulse converters.

The LM317T is also popular, I have not met with it, so I had to look for the correct datasheet for it for a long time. It turned out that they are completely identical in parameters, the letters "T" at the end of the marking indicate the TO-220 package at 1.5 Amperes.

Download datasheets:

  1. full ;


Even with integrated protection systems, it should not be exploited to the limit. If it fails, it is not known how many Volts will be at the output, it will be possible to burn an expensive load.

I will give the main electrical characteristics from the LM317 datasheet in Russian. Not everyone knows the technical terms in English.

The datasheet indicates a huge scope, it is easier to write where it is not used.


There are many microcircuits that have practically the same functionality, domestic and foreign. I will add more powerful analogs to the list in order to avoid including several in parallel. The most famous analogue LM317 is the domestic KR142EN12.

  1. LM117 LM217 - extended operating temperature range from -55 ° to + 150 °;
  2. LM338, LM138, LM350 - analogs for 5A, 5A and 3A, respectively;
  3. LM317HV, LM117HV - output voltage up to 60V, if standard 40V is not enough for you.

Full analogs:

  • GL317;
  • SG317;
  • UPC317;
  • ECG1900.

Typical connection schemes

 Regulator 1.25 - 20 Volt with adjustable current


To make the calculations as easy as possible on the basis of the LM317T, many LM317 calculator programs and online calculators have been developed . By specifying the initial parameters, you can immediately calculate several options and see the characteristics of the required radio components.

Program for calculating voltage and current sources, taking into account the LM317 characteristics of the LM317T. Calculation of switching circuits for powerful converters using transistors, TL431, M5237. Also IC 7805, 7809, 7812.

Connection diagrams

The LM317 stabilizer has established itself as a universal microcircuit capable of stabilizing voltage and amperes. Over the decades, hundreds of LM317T switching circuits have been developed for various applications. The main purpose is a voltage stabilizer in power supplies. To increase the strength of the number of Amperes at the output, there are several options:

  1. parallel connection;
  2. installation at the output of power transistors, we get up to 20A;
  3. replacement for powerful analogues LM338 up to 5A or LM350 up to 3A.

To build a bipolar power supply, negative voltage stabilizers LM337 are used.

I think that parallel connection is not the best option due to the difference in the characteristics of the stabilizers. It is impossible to adjust several pieces to exactly the same parameters in order to distribute the load evenly. Due to the spread, one load will always be more than others. The probability of failure of a loaded element is higher, if it burns out, then the load on others will sharply increase, which may not withstand it.

In order not to connect in parallel, it is better to use transistors at the output for the power section of the DC-DC voltage converter. They are designed for high current and heat dissipation is better due to their large size.

Modern pulse microcircuits are inferior in popularity, its simplicity is difficult to surpass. The current stabilizer on lm317 for LEDs is easy to configure and calculate, currently it is still used in small production of electronic components.

Bipolar power supply unit LM317 and LM337, for obtaining positive and negative voltage.

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