The **MAH21FAA-R** is an axial cooling fan manufactured by **Nidec Copal Electronics** (now often part of Nidec Advanced Motor). It is designed for high-performance thermal management in electronic enclosures and power supplies. --- ### 1. Technical Specifications Below are the primary electrical and mechanical specifications for the MAH21FAA-R: | Parameter | Specification | | :--- | :--- | | **Rated Voltage** | 12 VDC | | **Operating Voltage Range** | 7.0 ~ 13.8 VDC | | **Rated Current** | 0.16 A (approx. 1.92 Watts) | | **Speed** | 3,100 RPM | | **Airflow** | 33.9 CFM (Cubic Feet per Minute) | | **Static Pressure** | 33.3 Pa | | **Noise Level** | 31.0 dB(A) | | **Bearing Type** | Dual Ball Bearing | | **Dimensions** | 80mm x 80mm x 25mm | --- ### 2. Key Electronic Features #### A. Motor Construction The unit utilizes a **Brushless DC (BLDC) motor**. Unlike brushed motors, BLDC motors use electronic commutation, which reduces electromagnetic interference (EMI) and significantly extends the lifespan of the component because there are no physical brushes to wear down. #### B. Protection Circuitry The "R" suffix in the part number typically denotes specific internal protection or signal features: * **Reverse Polarity Protection:** Prevents damage to the internal PCB if the positive and negative leads are swapped accidentally. * **Auto-Restart:** If the fan blades are physically obstructed, the motor will cut power to prevent overheating and attempt to restart once the obstruction is removed. #### C. Dual Ball Bearing System The MAH21FAA-R uses a precision dual ball bearing system. Compared to "sleeve" bearings, ball bearings allow the fan to be mounted in any orientation (vertical, horizontal, or angled) without degrading the lifespan and are rated for much higher operating temperatures. --- ### 3. Wiring Configuration The standard MAH21FAA-R usually features a 2-wire or 3-wire lead configuration: * **Red Wire:** Positive DC Power (+12V). * **Black Wire:** Ground (GND). * **White/Yellow Wire (Optional):** Often used for a **Tachometer (FG)** signal or **Locked Rotor Alarm**, allowing the host system to monitor the fan's RPM or detect a failure. --- ### 4. Application Use Cases Due to its 80mm form factor and 12V rating, it is commonly found in: * **Server Racks:** For localized spot cooling of processors. * **Industrial Power Supplies:** To dissipate heat from MOSFETs and transformers. * **Telecommunications Gear:** Where long-term reliability (MTBF) is critical.