The **PUM-3546L-R** is a high-sensitivity **Omnidirectional Electret Condenser Microphone (ECM)**. These components are widely used in consumer electronics for audio recording and voice communication due to their small form factor and reliability. --- ### 1. Technical Specifications The following table outlines the primary electrical and physical characteristics of the PUM-3546L-R: | Parameter | Specification | | :--- | :--- | | **Directional Characteristic** | Omnidirectional (picks up sound from all directions) | | **Sensitivity** | -46 ± 3 dB (0dB = 1V/Pa, 1kHz) | | **Standard Operating Voltage** | 2.0 V | | **Maximum Operating Voltage** | 10 V | | **Current Consumption** | Max 0.5 mA | | **Impedance** | Max 2.2 kΩ | | **Frequency Range** | 20 Hz – 16,000 Hz | | **Signal-to-Noise Ratio** | > 58 dB | | **Dimensions** | 3.5mm (Diameter) x 4.6mm (Height) | --- ### 2. Internal Electronic Structure The PUM-3546L-R operates on the principle of changing capacitance. Internally, it consists of two main electronic elements: 1. **Electret Diaphragm:** A permanently charged material (electret) that moves in response to sound pressure waves, changing the capacitance between it and a backplate. 2. **Junction Field-Effect Transistor (JFET):** Since the impedance of the capsule is extremely high, a built-in JFET acts as an impedance converter. It transforms the high-impedance signal into a low-impedance signal suitable for standard audio pre-amplifiers. --- ### 3. Application Circuit (Typical) To use this part in an electronic circuit, you must provide a "Bias Voltage" through a load resistor. ```mermaid [VCC (2.0V)] | [RL (2.2kΩ)] | +----[ Output Coupling Capacitor (0.1uF - 10uF) ]----> Audio Out | [PUM-3546L-R] | [GND] ``` --- ### 4. Key Features * **Compact Size:** The 3.5mm diameter makes it ideal for wearable devices, smartphones, and miniature voice recorders. * **Solder Pads:** The "L" in the part number often denotes lead-type or specific pad configurations (depending on the manufacturer's datasheet variant), while the "R" usually indicates RoHS compliance. * **Omnidirectional Polar Pattern:** It provides a natural sound capture without the "proximity effect" found in directional microphones.