The **M5R78RH-R** is a high-performance, radiation-hardened (Rad-Hard) voltage regulator, typically used in aerospace, satellite, and military applications. It belongs to the STMicroelectronics family of radiation-hardened components. --- ### 1. General Specifications The device is designed to provide a stable 5V output even in environments exposed to high levels of ionizing radiation. | Parameter | Specification | | :--- | :--- | | **Output Voltage** | +5V (Fixed) | | **Input Voltage Range** | 7V to 12V | | **Output Current** | Up to 1.5A | | **Package Type** | TO-257 (Hermetic Metal Package) | | **Operating Temp Range** | -55°C to +125°C | --- ### 2. Key Electronic Features * **Radiation Hardness:** * **TID (Total Ionizing Dose):** Capable of withstanding up to 300 krad(Si). * **SEL (Single Event Latch-up):** Immune to SEL up to 110 $MeV \cdot cm^2/mg$. * **Low Dropout (LDO):** It is a positive voltage regulator characterized by a relatively low dropout voltage for its power class. * **Internal Protection:** * **Thermal Overload Protection:** Automatically shuts down if the internal temperature exceeds safety limits. * **Short-Circuit Protection:** Limits current to prevent damage during a fault. * **Hermetic Sealing:** The "R" suffix and the TO-257 package indicate it is hermetically sealed to prevent moisture and gas ingress, which is critical for vacuum environments (space). --- ### 3. Pinout Configuration The TO-257 package typically utilizes three pins. While you should always consult the specific datasheet for the current revision, the standard layout is: | Pin Number | Function | Description | | :--- | :--- | :--- | | **1** | **INPUT** | Unregulated DC input voltage | | **2** | **GROUND** | Common ground (Case is often connected) | | **3** | **OUTPUT** | Regulated +5V DC output | --- ### 4. Typical Application Circuit To ensure stability, especially in high-reliability environments, external capacitors are required. ```c // Simplified Schematic Concept [Input Voltage] ----+----[ IN M5R78RH-R OUT ]----+---- [5V Output] | [ GND ] | Cin (0.33uF) | Cout (0.1uF) | | | Ground --------- Ground --------- Ground ``` --- ### 5. Why use the M5R78RH-R? This part is chosen over standard consumer regulators (like the LM7805) when the system will be deployed in: 1. **Low Earth Orbit (LEO) Satellites:** Protection against solar protons and cosmic rays. 2. **Scientific Probes:** Long-duration missions where component degradation must be predictable. 3. **Nuclear Instrumentation:** High-radiation terrestrial environments.