The **POM-2746L-R** is a high-performance, omnidirectional **electret condenser microphone (ECM)** capsule manufactured by PUI Audio. It is widely used in telecommunications, security systems, and consumer electronics due to its compact size and high sensitivity. --- ### ## Technical Specifications Below are the primary electrical and physical characteristics of the POM-2746L-R: | Parameter | Specification | | :--- | :--- | | **Directional Characteristic** | Omnidirectional | | **Sensitivity** | -46 ± 3 dB (0dB=1V/Pa, 1kHz) | | **Operating Voltage Range** | 1.5V ~ 10V DC | | **Rated Voltage** | 2.0V DC | | **Current Consumption** | 0.5 mA (Maximum) | | **Frequency Range** | 50 Hz ~ 16,000 Hz | | **Signal-to-Noise Ratio** | > 60 dB | | **Output Impedance** | 2.2 kΩ | | **Dimensions** | 6.0mm (Diameter) x 2.7mm (Height) | | **Termination** | Solder Pads (Leadless) | --- ### ## Internal Structure and Operation The POM-2746L-R operates based on the principles of an electret condenser: 1. **The Diaphragm:** A thin, metalized plastic film (the electret) acts as one plate of a capacitor. It carries a permanent electrostatic charge. 2. **The Backplate:** A rigid metal plate that acts as the second electrode. 3. **The JFET:** Because the capsule has very high impedance, an internal **Junction Field Effect Transistor (JFET)** is integrated to act as an impedance converter/pre-amplifier. 4. **Signal Generation:** As sound waves hit the diaphragm, the capacitance changes, creating a small voltage fluctuation that the JFET converts into an electrical signal. --- ### ## Key Features and Application Notes * **Omnidirectional Polar Pattern:** This means the microphone picks up sound equally from all directions. It is ideal for devices where the source of the sound may move or where ambient sound needs to be captured. * **Low Profile:** With a height of only 2.7mm, it is suitable for thin handheld devices like smartphones or wearable tech. * **External Circuitry Requirement:** As an ECM, it requires a "bias voltage" (Phantom Power) through a load resistor (usually 2.2kΩ) to operate the internal JFET. #### ### Typical Connection Diagram ```text (Vcc) ---- [Resistor 2.2k] ----+---- Output Signal (To Pre-amp) | [POM-2746L-R] | (GND) ``` ---