### LD1085D2M90-R Electronic Component Overview The **LD1085D2M90-R** is a high-performance, low-dropout (LDO) positive voltage regulator produced by STMicroelectronics. It is designed to provide a stable, fixed output voltage while maintaining high current capability. --- ### 1. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Output Voltage** | Fixed 9.0V | | **Output Current** | Up to 3.0A | | **Dropout Voltage** | Typically 1.3V at 3A | | **Input Voltage (Max)** | 30V | | **Package Type** | D2PAK (TO-263) | | **Operating Temperature** | -40°C to 125°C | | **Line Regulation** | 0.015% (Typical) | | **Load Regulation** | 0.1% (Typical) | --- ### 2. Functional Characteristics The LD1085 series is an evolution of the industry-standard 1085 series, offering enhanced efficiency and thermal stability. * **Low Dropout Performance:** Unlike standard linear regulators (like the LM7809) that require 2-3V of "headroom," the LD1085 can function with a significantly smaller difference between input and output voltage. * **High Current Delivery:** Capable of delivering up to 3 Amperes, making it suitable for high-power digital circuits and motor drivers. * **Protection Circuitry:** * **Current Limiting:** Protects the device during short-circuit conditions. * **Thermal Overload Protection:** Shuts down the regulator if the internal junction temperature exceeds safe limits. --- ### 3. Pin Configuration (D2PAK) The device typically utilizes three main connections: 1. **Pin 1 (Adjust/Ground):** Connected to ground for this fixed 9.0V version. 2. **Pin 2 (Output):** The regulated 9.0V output (also connected to the large metal tab for heat dissipation). 3. **Pin 3 (Input):** The unregulated DC supply voltage. --- ### 4. Implementation Example To ensure stability, the LD1085 requires specific capacitors on the input and output. ```c // Typical Application Schematic Requirements Input Voltage (Vin) > 10.3V (9V + 1.3V Dropout) Components: - Cin: 10µF Tantalum or Electrolytic (removes high-frequency noise) - Cout: 10µF to 22µF Tantalum (essential for loop stability) ``` --- ### 5. Common Applications * **Post-regulators for Switching Supplies:** To filter out high-frequency ripple. * **Battery Chargers:** Efficiently managing charging currents. * **Microprocessor Power Supplies:** Providing clean power to high-draw embedded systems. * **Industrial Automation:** 9V logic supply for sensors and actuators.