The **M3H28TDD-R** is a high-performance, radiation-hardened (RadHard) isolated DC-DC converter specifically designed for space and satellite applications. It is manufactured by International Rectifier (now part of Infineon Technologies). --- ## 1. Core Technical Specifications The "M3H" series represents a specific class of high-reliability converters. Below are the primary electronic characteristics: | Feature | Specification | | :--- | :--- | | **Input Voltage Range** | 18V to 50V DC (28V Nominal) | | **Output Voltage** | Dual Outputs (typically ±12V or ±15V depending on config) | | **Output Power** | Up to 40 Watts | | **Efficiency** | Up to 82% | | **Isolation** | 100MΩ @ 500VDC | | **Operating Temp** | -55°C to +85°C (Case) | --- ## 2. Key Electronic Components & Architecture The device utilizes a sophisticated internal topology to ensure stability in harsh environments: ### A. Magnetic Feedback Unlike commercial converters that use optoisolators (which degrade under radiation), the M3H28TDD-R uses **magnetic feedback**. This ensures long-term reliability and prevents loop gain shifts caused by Total Ionizing Dose (TID). ### B. Radiation Hardening (RadHard) * **TID (Total Ionizing Dose):** Guaranteed performance up to **100 krad(Si)**. * **SEE (Single Event Effects):** Rated for Heavy Ion environments; immune to Single Event Latch-up (SEL) up to an LET of **82 MeV·cm²/mg**. ### C. Protection Circuitry 1. **Input Undervoltage Lockout (UVLO):** Prevents the unit from operating during brown-out conditions to protect the internal MOSFETs. 2. **Overload/Short Circuit Protection:** Features a "hiccup" mode or current limiting to prevent thermal runaway. 3. **Soft-Start:** Minimizes inrush current during startup to prevent bus voltage drops. --- ## 3. Physical & Mechanical Parts The construction is as critical as the electronic design for space survival. * **Package:** Hermetically sealed, low-profile metal case. * **Lead Finish:** Gold-plated leads to prevent "tin whiskers" in vacuum environments. * **Weight:** Approximately 110 grams. --- ## 4. Pin Configuration Overview The "TDD" suffix usually denotes a triple or dual output configuration. Common pins include: | Pin Type | Description | | :--- | :--- | | **Vin / Vout** | Main power input and regulated output rails. | | **Share** | Allows for parallel operation with other units. | | **Inhibit** | A logic-level input to turn the converter ON or OFF remotely. | | **Adjust** | Allows the user to trim the output voltage slightly (±10%). |