## LM317ML-TN3-R: Electronic Specifications and Overview The **LM317ML-TN3-R** is a specific variant of the widely used LM317 family. It is an adjustable 3-terminal positive voltage regulator capable of supplying in excess of 100mA over an output voltage range of 1.2V to 37V. ### 1. Part Number Breakdown The suffixing on this specific part (likely manufactured by **UTC - Unisonic Technologies**) defines its package and delivery method: * **LM317ML**: The "M" typically denotes the medium-current version (100mA to 500mA range depending on thermal management). * **TN3**: Refers to the **TO-252 (D-PAK)** surface-mount package. * **R**: Indicates **Tape & Reel** packaging for automated assembly. --- ### 2. Key Technical Specifications | Parameter | Value | | :--- | :--- | | **Output Voltage Range** | 1.2V to 37V | | **Output Current** | 100mA (Minimum guaranteed) | | **Input-Output Differential** | 40V (Maximum) | | **Line Regulation** | 0.01% / V (Typical) | | **Load Regulation** | 0.1% (Typical) | | **Reference Voltage ($V_{ref}$)** | 1.25V | | **Operating Temperature** | -40°C to +125°C | --- ### 3. Pin Configuration (TO-252) When looking at the front of the component (leads pointing down): 1. **ADJ (Adjust)**: The feedback pin used to set the output voltage via a resistor divider. 2. **Vout (Output)**: The regulated output voltage (internally connected to the large thermal tab). 3. **Vin (Input)**: The unregulated input voltage. --- ### 4. Typical Application Circuit To set the output voltage, two external resistors ($R1$ and $R2$) are required. The formula is: $$V_{out} = V_{ref} \left(1 + \frac{R2}{R1}\right) + (I_{adj} \times R2)$$ ```python # Standard Resistor Values Example: # R1 = 240 Ohms (connected between Vout and ADJ) # R2 = Potentiometer or Fixed Resistor (connected between ADJ and Ground) # Vref = 1.25V ``` --- ### 5. Notable Features * **Internal Protection**: Includes current limiting, thermal overload protection, and safe-area compensation. These remain functional even if the adjustment terminal is disconnected. * **Floating Operation**: The regulator "floats" on the output voltage. As long as the input-to-output differential does not exceed 40V, it can regulate high-voltage supplies. * **Elimination of Stockpiling**: By using an adjustable regulator, designers do not need to stock multiple fixed-voltage regulators (5V, 9V, 12V, etc.).