The **ATR2805S** is a high-reliability, radiation-hardened (RadHard) DC-DC converter designed specifically for space and aerospace applications. It belongs to a family of hybrid microcircuit converters known for their compact size and extreme environmental tolerance. --- ### 1. Key Technical Specifications The "2805S" nomenclature typically breaks down as follows: **28** (28V nominal input), **05** (5V output), and **S** (Single output). | Feature | Specification | | :--- | :--- | | **Input Voltage Range** | 16V to 40V DC (Standard 28V Bus) | | **Output Voltage** | 5.0V DC | | **Output Power** | Up to 30 Watts | | **Efficiency** | ~75% to 80% (Typical) | | **Isolation** | 100MΩ @ 500VDC (Input to Output) | | **Operating Temp** | -55°C to +125°C | --- ### 2. Internal Electronic Components & Design The device is a **Hybrid Microcircuit**, meaning it combines discrete components with semiconductor dies on a ceramic substrate. * **Power Stage:** Utilizes high-frequency switching (typically ~400kHz to 500kHz) to minimize the size of inductors and capacitors. It uses a flyback or forward converter topology. * **Magnetic Feedback:** To maintain galvanic isolation between the input and output while providing tight regulation, it uses an internal transformer for feedback rather than optocouplers (which degrade in radiation environments). * **Input/Output Filters:** Contains internal EMI filters to meet MIL-STD-461 requirements, reducing conducted emissions back into the power bus. * **Protection Circuitry:** * **Under-Voltage Lockout (UVLO):** Prevents operation if the input voltage is too low. * **Short Circuit Protection:** Features pulse-by-pulse current limiting and "hiccup" mode for permanent shorts. * **Overvoltage Protection:** Ensures sensitive downstream electronics (like FPGAs or CPUs) are not damaged. --- ### 3. Radiation Hardness (RadHard) Features Unlike commercial converters, the ATR2805S is built to survive the harsh environment of space: 1. **Total Ionizing Dose (TID):** Usually rated for **100 krad(Si)** or more, ensuring long-term survival against cosmic radiation. 2. **Single Event Effects (SEE):** Designed to be immune to "Latch-up" (SEL) and resilient against "Burnout" (SEB) caused by heavy ions. 3. **Hermetic Packaging:** The electronics are housed in a seam-welded, metal-leaded package to prevent outgassing and protect against the vacuum of space. --- ### 4. Application Use Cases * **Satellites:** Powering command and data handling (C&DH) systems. * **Launch Vehicles:** Providing regulated power to telemetry and guidance systems. * **Deep Space Probes:** Where high efficiency and reliability are non-negotiable over long missions.