The **MH21FDD-R** is a specific electronic component typically identified as a **Micro-SD Card Connector** or an integrated **Flash Card Reader Interface**. These parts are crucial in devices requiring external storage, such as smartphones, tablets, and embedded IoT systems. --- ### 1. Component Specifications Below are the typical technical characteristics found in the MH21FDD-R series: | Feature | Description | | :--- | :--- | | **Component Type** | Micro-SD (TF) Card Connector | | **Mounting Type** | Surface Mount Device (SMD/SMT) | | **Mechanical Action** | Push-Push (or Push-Pull) Mechanism | | **Number of Pins** | 8 Signal Pins + Ground/Shield Shell | | **Material** | High-temperature Thermoplastic (Housing), Copper Alloy (Contacts) | | **Plating** | Gold over Nickel (on contact area) | --- ### 2. Key Electronic Characteristics * **Contact Resistance:** Generally rated at a maximum of **100mΩ**. Low resistance is vital for high-speed data transfer (UHS-I/II standards). * **Insulation Resistance:** Typically minimum **1000MΩ** at 500V DC to prevent signal leakage between pins. * **Current Rating:** Approximately **0.5A per pin**. While SD cards don't draw much power, stable current delivery is necessary for write operations. * **Voltage Rating:** Rated for **10V to 30V AC/DC**, though standard Micro-SD operation is at 1.8V or 3.3V. --- ### 3. Pinout Configuration While the physical footprint is proprietary, the electronic interface follows the SD standard: 1. **DAT2:** Data Line 2 2. **CD/DAT3:** Card Detect / Data Line 3 3. **CMD:** Command/Response 4. **VDD:** Supply Voltage (3.3V/1.8V) 5. **CLK:** Clock Signal 6. **VSS:** Ground 7. **DAT0:** Data Line 0 8. **DAT1:** Data Line 1 --- ### 4. Physical Layout & PCB Considerations * **Shielding:** The metal "R" (Reverse or Reinforced) shell is usually soldered to the PCB ground plane to reduce Electromagnetic Interference (EMI) and provide structural integrity. * **Switch Detect:** Most MH21FDD-R models include a "Card Insertion Detection" switch, which is a physical lever that closes a circuit when a card is fully seated.