3 pin regulator LM317 constant current calculator
| This is a constant current circuit with the 3 pin regular "LM317". The constant current property can be achieved by inserting a single resistor between "out" and "adj" pin. According to data sheet, voltage between LM317's "out-adj" will be "1.25V±0.05V". The resistor "R" will control the amount of current output. To stablize the circuit 0.1μF capacitor will be added to input, and 1μF or larger for output. | ||
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Constant Current (mA) = 1.25V÷R (Ω) |
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Credit: http://www15.plala.or.jp/gundog/index.html
LM350T output 3A, LM338T output 5A, different between LM317 is the maximum current can handle, other parameter's almost the same. |
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| 定電流値 (constant current) | 抵抗値 (resistor value) | 合成使用抵抗値 (resistor in parallel) |
| 265mA | 4.7Ω | - |
| 250mA | 5Ω | 10Ω+10Ω |
| 152mA | 8.2Ω | 10Ω+47Ω |
| 125mA | 10Ω | - |
| 53.2mA | 23.5Ω | 47Ω+47Ω |
| 49.0mA | 25.5Ω | 51Ω+51Ω |
| 33.3mA | 37.5Ω | 75Ω+75Ω |
| 26.5mA | 47Ω | - |
| 25.0mA | 50Ω | 100Ω+100Ω |
| 24.5mA | 51Ω | - |
| 20.8mA | 60Ω | 120Ω+120Ω |
| 16.7mA | 75Ω | - |
| 12.5mA | 100Ω | - |
| 10.4mA | 120Ω | - |
| 10.0mA | 125Ω | 150Ω+750Ω |
| 8.3mA | 150Ω | - |