The **M3H28FAG-R** is a high-performance, radiation-hardened (Rad-Hard) isolated DC-DC converter specifically designed for space, aerospace, and high-reliability defense applications. It is manufactured by **VPT Inc.** (part of HEICO Electronic Technologies). --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Input Voltage Range** | 18V to 50V DC (28V Nominal) | | **Output Voltage** | Single 5V DC (Adjustable) | | **Output Power** | Up to 25 Watts | | **Efficiency** | Typically 80% to 84% | | **Isolation** | 100MΩ @ 500VDC | | **Operating Temp** | -55°C to +125°C | --- ### 2. Functional Electronic Components The internal architecture of the M3H28FAG-R utilizes several critical electronic systems to ensure stability in harsh environments: * **Magnetic Feedback Loop:** Unlike commercial converters that use optocouplers (which degrade under radiation), this unit uses a proprietary magnetic feedback system to maintain galvanic isolation and long-term reliability. * **Input/Output Filters:** Integrated LC filters reduce conducted emissions and output ripple, ensuring high power quality for sensitive satellite payloads. * **Protection Circuitry:** * **Under-Voltage Lockout (UVLO):** Prevents the device from operating until the input voltage is high enough for stable regulation. * **Current Limiting:** Protects the internal power MOSFETs and the load from short-circuit conditions. * **Soft Start:** Gradually increases output voltage to prevent high inrush currents during startup. --- ### 3. Radiation Hardness & Reliability The "R" suffix in the part number often denotes specific radiation testing levels. * **TID (Total Ionizing Dose):** Characterized to withstand radiation levels typically up to **100 krad(Si)**. * **SEE (Single Event Effects):** Designed to be immune to Single Event Latch-up (SEL) and resilient against Single Event Upsets (SEU) and Burnout (SEB) up to an LET of **82 MeV-cm²/mg**. * **Packaging:** Housed in a hermetically sealed, low-profile metal case to prevent outgassing in vacuum environments. --- ### 4. Pin Configuration and Control Features The device features specialized pins for system integration: 1. **Inhibit:** Allows the converter to be turned on/off remotely with a logic signal. 2. **Sync:** Allows the internal switching frequency to be synchronized with an external clock to manage EMI. 3. **Trim:** Permits the user to adjust the output voltage slightly (e.g., from 5V to 5.2V) to compensate for line drops. ---