The **DM3N-R** is a specific model of microSD card connector manufactured by **Hirose Electric Co., Ltd.** It is widely used in mobile devices, embedded systems, and consumer electronics due to its extremely compact form factor and robust design. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Connector Type** | microSD Card (TransFlash) | | **Mounting Type** | Surface Mount (SMT), Right Angle | | **Ejection Mechanism** | Push-Push (Manual push to insert, manual push to eject) | | **Number of Contacts** | 8 Pins + 1 Switch (Card Detection) | | **Current Rating** | 0.5A | | **Voltage Rating** | 125V AC | | **Durability** | 5,000 mating cycles | --- ### 2. Major Electronic & Structural Components #### A. Contact Terminals The connector features 8 signal pins made of a copper alloy with **gold plating** over nickel. Gold is used to prevent oxidation and ensure stable electrical conductivity over thousands of insertions. #### B. Push-Push Mechanism Unlike "Push-Pull" connectors, the DM3N-R uses a spring-loaded mechanical heart-cam system. * **Insertion:** The card clicks into place and is held by a latch. * **Ejection:** Pushing the card again releases the spring, partially ejecting the card for easy removal. #### C. Card Detection Switch The "R" suffix often denotes specific configurations including a **Normally Open (NO)** detection switch. This is a small internal mechanical lever that closes a circuit when a card is fully inserted, sending a signal to the microcontroller (MCU) to initialize the SD interface. #### D. Shielding and Grounding The outer shell is made of stainless steel. It serves two purposes: 1. **EMI Shielding:** Protects the high-speed data signals from electromagnetic interference. 2. **Structural Integrity:** Multiple solder tabs (SMT leads) on the shell provide mechanical "anchors" to the PCB to prevent the connector from being ripped off during rough handling. --- ### 3. Pinout Configuration (Standard microSD) | Pin No. | Name | Description | | :--- | :--- | :--- | | 1 | DAT2 | Data Line 2 | | 2 | CD/DAT3 | Card Detect / Data Line 3 | | 3 | CMD | Command/Response | | 4 | VDD | Supply Voltage (2.7V - 3.6V) | | 5 | CLK | Clock | | 6 | VSS | Supply Voltage Ground | | 7 | DAT0 | Data Line 0 | | 8 | DAT1 | Data Line 1 | --- ### 4. Application Hardware Design When integrating the DM3N-R into a circuit, engineers typically include: * **Decoupling Capacitors:** Usually 0.1µF and 10µF placed near the VDD pin to stabilize voltage during high-speed data bursts. * **Pull-up Resistors:** Generally 10kΩ to 100kΩ resistors on the CMD and DAT lines to maintain high logic levels when the lines are idle.