The **M3H28FBG-R** is a high-performance, radiation-hardened DC-DC converter module developed by **VPT**, designed specifically for space and high-reliability aerospace applications. --- ## 1. Technical Specifications The M3H series represents a milestone in hybrid power conversion, offering high efficiency and extreme durability. | Feature | Specification | | :--- | :--- | | **Input Voltage Range** | 18V to 50V DC (28V Nominal) | | **Output Voltage** | 5V DC (Fixed) | | **Output Power** | Up to 25 Watts | | **Efficiency** | ~80% to 82% | | **Isolation** | 100MΩ @ 500VDC | | **Operating Temp** | -55°C to +125°C | | **Package Style** | Hermetic, Flanged Metal Case | --- ## 2. Key Electronic Characteristics ### Radiation Hardness (Rad-Hard) This is the defining feature of the "M3H" line. It is designed to survive the harsh environment of Earth's orbit and deep space: * **TID (Total Ionizing Dose):** Characterized up to 100 krad(Si). * **SEE (Single Event Effects):** Immune to SEE with LET (Linear Energy Transfer) up to 82 MeV·cm²/mg. ### Protection Circuitry The module incorporates internal features to protect both the source and the load: * **Soft Start:** Limits inrush current during startup. * **Magnetic Feedback:** Uses magnetic coupling instead of optoisolators (which degrade under radiation) to maintain voltage regulation. * **Short Circuit & Overload Protection:** Indefinite protection with automatic recovery. --- ## 3. Pin Configuration & Functionality The module typically uses a multi-pin header system. Below are the primary functional pins found in this series: | Pin Type | Description | | :--- | :--- | | **Input (+/-)** | DC Input power (18-50V). | | **Output (+/-)** | Regulated 5V output power. | | **Inhibit** | Logic level signal to turn the converter ON or OFF. | | **Sense (+/-)** | Remote sensing to compensate for voltage drops in wiring. | | **Adjust** | Allows the user to "trim" the output voltage slightly. | | **Case Ground** | Connection to the metal chassis for EMI shielding. | --- ## 4. Part Number Breakdown The nomenclature `M3H28FBG-R` tells us the exact build: * **M3H:** Series designation (High-density, Rad-Hard). * **28:** Nominal Input Voltage (28V). * **F:** Dual/Single configuration indicator (F usually denotes a specific output variant). * **B:** Screening level (Military/Space grade). * **G:** Package/Mounting style (Flanged). * **-R:** Indicates "Radiation Hardened" certification.