The **79D12AL-TM3-R** is a specific part number for a negative voltage regulator. This component is part of the standard "79xx" series, which is designed to provide a stable, fixed negative output voltage from a fluctuating DC input. ### General Specifications | Feature | Details | | :--- | :--- | | **Part Family** | 79xx Series (Negative Voltage Regulator) | | **Output Voltage** | -12V (Fixed) | | **Output Current** | Typically up to 1.0A or 1.5A (depending on thermal dissipation) | | **Polarity** | Negative | | **Package Type** | TO-251 (IPAK) or TO-252 (DPAK) variants (TM3 often refers to TO-251) | | **Mounting Type** | Through-hole or Surface Mount (model dependent) | --- ### Key Technical Characteristics 1. **Fixed Output:** The "12" in the part number indicates a fixed **-12V** output. It is not adjustable. 2. **Protection Features:** * **Internal Thermal Overload Protection:** Shuts down the device if it gets too hot. * **Short Circuit Current Limiting:** Prevents the device from burning out if the output is shorted to ground. * **Safe-Area Compensation:** Ensures the internal transistor operates within safe limits. 3. **Dropout Voltage:** This is a linear regulator, meaning the input voltage must be at least 2V–3V more negative than the output (e.g., an input of -14.5V to -15V is required for a stable -12V output). --- ### Pin Configuration For most TO-251/TO-252 packages in the 79xx series, the pinout is different from the positive (78xx) series. **Always verify with the specific UTC (Unisonic Technologies) datasheet:** 1. **Pin 1 (GND):** Ground reference. 2. **Pin 2 (IN):** Negative Input voltage. 3. **Pin 3 (OUT):** Regulated -12V Output. *Note: The metal tab is usually connected to the Input (Pin 2).* --- ### Application Example The 79D12AL is frequently used in **Dual Power Supplies** to provide the negative rail for operational amplifiers (Op-Amps). ```c // Typical Dual Rail Setup Positive Rail: 7812 (+12V) Common: Ground (0V) Negative Rail: 79D12AL (-12V) ``` --- ### Decoding the Suffixes (UTC Standards) * **79D12:** Negative 12V Regulator. * **L:** Lead-free/Halogen-free. * **TM3:** Package code (usually TO-251). * **R:** Tape & Reel or specific packing method.