# LD1085D2T80-R Electronic Components & Specifications The **LD1085D2T80-R** is a low-drop positive voltage regulator capable of providing up to **3A** of output current. It is manufactured by **STMicroelectronics** and belongs to the LD1085 series, which are high-efficiency alternatives to standard linear regulators. --- ### ## 1. Key Technical Specifications The part number indicates a specific fixed output voltage and package type. | Feature | Specification | | :--- | :--- | | **Output Voltage** | 8.0V (Fixed) | | **Output Current** | 3.0 A (Maximum) | | **Dropout Voltage** | 1.3V (Typical at 3A) | | **Input Voltage (Max)** | 30V | | **Package Type** | D2PAK (TO-263) | | **Operating Temp** | -40°C to 125°C | | **Voltage Tolerance** | ±1% at 25°C | --- ### ## 2. Core Functional Parts The internal circuitry of the LD1085D2T80-R consists of several critical stages: 1. **Series Pass Element:** A large NPN transistor that handles the heavy current flow from input to output. 2. **Voltage Reference:** A stable internal bandgap reference used to compare the actual output against the target 8V. 3. **Error Amplifier:** Constantly adjusts the base current of the pass transistor to maintain the fixed 8V output under varying loads. 4. **Protection Circuitry:** * **Internal Current Limiting:** Protects the device during short circuits or overloads. * **Thermal Overload Protection:** Shuts the device down if the junction temperature exceeds safe limits. --- ### ## 3. External Implementation To ensure stability and reduce noise, specific external passive components are required. ```c // Typical Application Circuit [Input Voltage] ----(In)--[LD1085]--(Out)---- [8.0V Output] | (Gnd) | [Ground] // Required Capacitors: // Input: 10µF Tantalum or Electrolytic (if far from power source) // Output: 10µF Tantalum (Required for stability) ``` --- ### ## 4. Pin Configuration (D2PAK) The D2PAK is a surface-mount package designed for high power dissipation. * **Pin 1 (Adjust/GND):** Connected to ground for this fixed 8V version. * **Pin 2 (Output):** The regulated 8V supply. (Also connected to the large metal tab). * **Pin 3 (Input):** The unregulated DC supply voltage. --- ### ## 5. Advantages of the LD1085 Series * **Low Dropout:** Unlike standard regulators (like the 7808) which require ~2-3V overhead, this only requires ~1.3V, allowing it to work with lower input voltages. * **High Current:** Supporting 3A makes it suitable for high-power logic, motor controllers, and communication modules.