LM337T Adjustable Negative Linear Voltage Regulator — Datasheet, Pinout & Circuit
The LM337T is a negative adjustable linear regulator from Texas Instruments. The LM337T is a three-terminal adjustable negative linear voltage regulator, complementary to the LM317T. Capable of supplying more than 1.5A over an output voltage range of -1.2V to -37V.
What is the LM337T?
The LM337T is a Negative adjustable linear regulator from the LM337 series by Texas Instruments. Primary applications:
- Dual power supplies
- Operational amplifiers
- Audio systems
- Laboratory supplies
- Negative voltage references
Key Specifications
- Output Voltage: -1.2V to -37V (adjustable)
- Maximum Current: 1.5A
- Type: Negative adjustable linear regulator
- Package: TO-220
- Dropout Voltage: 2V
Datasheet and Pinout
Pin configuration of LM337T regulator in TO-220 package
| Pin | Name | Function |
|---|---|---|
| 1 | ADJ | Adjust terminal |
| 2 | OUT | Negative output voltage |
| 3 | IN | Negative input voltage |
📄 Official Datasheet: Download PDF
TO-220 Visual identification: With the flat side facing you and pins pointing down, the pins run left to right as shown in the table above.
Technical Specifications
| Parameter | Value |
|---|---|
| Output Voltage | -1.2V to -37V (adjustable) |
| Maximum Current | 1.5A |
| Regulator Type | Linear |
| Package | TO-220 |
| Dropout Voltage | 2V |
| Manufacturer | Texas Instruments |
| operating Voltage | -1.2V to -37V (output) |
| max Current | 1.5A |
| temperature | -55°C to +150°C |
| package Type | TO-220 |
| dropout | 2V typical |
| regulation | 0.01% typical |
| ripple Rejection | 80dB typical |
Typical Circuit
The LM337T requires minimal external components. The basic circuit includes:
- Input capacitor (C1): 0.1 µF – 1 µF (ceramic or electrolytic) between VIN and GND — filters input noise.
- Output capacitor (C2): 1 µF – 10 µF (electrolytic) between VOUT and GND — stabilizes output and improves transient response.
- Resistor network R1/R2: Sets the output voltage. VOUT = VREF × (1 + R2/R1) + IADJ × R2.
⚠️ Always add a heatsink if current exceeds 500mA or if the Vin – Vout difference is greater than 3V. Power dissipated: P = (Vin – Vout) × Iload.
Variants and Alternatives
| Component | Vout | Imax | Type |
|---|---|---|---|
| LM337 | — | — | Alternative |
| LM337K | — | — | Alternative |
| LM337L | — | — | Alternative |
Applications with Arduino and DIY Projects
The LM337T is ideal for projects requiring a clean, regulated supply:
- Power Arduino from 12V: Converts to -1.2V to -37V (adjustable) for the Arduino VIN pin.
- Breadboard prototypes: Minimal circuit (IC + 2 capacitors) fits any breadboard.
- Audio projects: Adjustable voltage for preamps and audio stages.
- Sensors and modules: Clean supply for DHT11, ultrasonic sensors, etc.
Frequently Asked Questions (FAQ)
What is the LM337T used for? It is a Negative adjustable linear regulator that converts a higher input voltage into a stable -1.2V to -37V (adjustable) output. The LM337T is a three-terminal adjustable negative linear voltage regulator, complementary to the LM317T. Capable of supplying more than 1.5A over an output voltage range of -1.2V to -37V.
How much current can the LM337T supply? Up to 1.5A continuously with an adequate heatsink. Without a heatsink, limit to 100–200 mA to prevent overheating.
Does the LM337T need a heatsink? Yes, when power dissipation P = (Vin – Vout) × I exceeds ~1W. For light loads (under 200 mA) with a small voltage difference, it can operate without a heatsink.
What is the difference between LM337T and its alternatives? The LM337 is a direct pin-compatible alternative. The main difference is usually the manufacturer (TI, Fairchild, ST) and slight variations in datasheet specifications.
Where can I buy the LM337T? At local electronics stores, eBay, Mouser, DigiKey, or AliExpress. For prototyping, breakout modules that include the IC with capacitors already mounted are also available.
What is the LM337T pinout? See the pinout table above. For the TO-220 package: with the flat side facing you and pins pointing down, the pin order is shown left to right in the table. Download the official datasheet for the complete diagram.