## Overview of LD1085CDT-R The **LD1085CDT-R** is a high-performance **Low Dropout (LDO)** voltage regulator. It is designed to provide a stable output voltage even when the input voltage is only slightly higher than the desired output. It is part of the LD1085 series produced by STMicroelectronics. --- ### 1. Key Technical Specifications | Parameter | Value / Range | | :--- | :--- | | **Regulator Type** | Positive Adjustable | | **Output Current** | Up to 3.0 Amperes | | **Dropout Voltage** | Typ. 1.3V at 3A | | **Input Voltage (Max)** | 30V | | **Output Voltage Range** | 1.25V to 28V | | **Package Type** | DPAK (TO-252) | | **Operating Temperature** | -40°C to 125°C | --- ### 2. Main Features * **High Current Capability:** Capable of delivering up to 3A, making it suitable for high-power logic circuits and microprocessors. * **Internal Protection:** Includes internal current limiting and thermal shutdown protection to prevent damage during overloads. * **Low Dropout:** Compared to standard regulators (like the LM317), it requires less "headroom" between input and output voltage. * **Stability:** Specifically designed to be stable with low ESR electrolytic or tantalum capacitors. --- ### 3. Pin Configuration (DPAK) The LD1085CDT-R usually follows the standard 3-pin layout for power regulators: 1. **ADJ / GND:** The adjustment pin for setting the output voltage (or ground for fixed versions). 2. **Vout (Tab):** The regulated output voltage (connected to the large thermal tab). 3. **Vin:** The unregulated input voltage. --- ### 4. Typical Application Circuit To set the output voltage, a resistive divider is used between the output, the adjustment pin, and ground. ```c // Calculation for Output Voltage: Vout = Vref * (1 + R2/R1) + (Iadj * R2) // Components: - C1 (Input): 10µF (Tantalum recommended) - C2 (Output): 10µF to 22µF (Ensures stability) - R1, R2: Precision resistors for voltage setting ``` --- ### 5. Common Use Cases * **Post-regulators** for high-efficiency switching power supplies. * **Battery Chargers:** Due to high current and thermal protection. * **Microprocessor Power:** Providing stable 1.8V, 2.5V, or 3.3V rails from a 5V source. * **Adjustable Power Supplies:** Ideal for benchtop DIY power modules.