🔧 LM317LZ – Adjustable Linear Voltage Regulator (TO‑92, 100 mA)
A miniature, three-terminal adjustable regulator in a TO‑92 package. Delivers up to 100 mA over a wide adjustable range from 1.2 V to 37 V, making it ideal for portable electronics, sensor modules, and DIY power supplies.
📊 Technical Specifications
| Parameter | Value & Notes |
|---|
| Output Voltage Range | 1.2 V – 37 V (programmable via resistor divider) |
| Output Current | Up to 100 mA |
| Line Regulation | ≈0.01% per volt |
| Load Regulation | ≈0.1% |
| Quiescent Current | ~5 mA |
| Thermal/Short-Circuit Protection | Built-in |
| Ripple Rejection | ~80 dB @120 Hz |
| Operating Temp Range | 0 °C to +125 °C (junction) |
| Max Input Voltage | ≤ 40 V |
| Pinout (TO-92) | 1 = Adj, 2 = Input, 3 = Output |
🔌 Arduino Wiring & Usage
Adjustable Power Supply Circuit
Connections:
Vin → Input power (e.g. 9 V battery)
Vout → Load / Arduino 5 V input
Adj → Resistor divider: R1 (240 Ω) to Vout and R2 from Vout to GND
Example Resistors (for ~5 V output):
CopyEdit
R1 = 240 Ω
R2 = (Vout/1.25 – 1) * R1 ≈ 720 Ω
Optional Capacitors:
🎥 YouTube Tutorial :
https://www.youtube.com/watch?v=L9Yo2nllYcc
"LM317 Voltage Regulator Tutorial | How to use?" — Covers pinout and applications for adjustable supply up to 37 V.
Another practical guide for Arduino power supply:
https://www.youtube.com/watch?v=rMVs1-FCP1k
"Make 5 volt power supply for Arduino using LM317"
📄 Datasheet & Resources
Official PDF:
