## Technical Overview: TOM-1545P-R The **TOM-1545P-R** is a high-sensitivity **Electret Condenser Microphone (ECM)** capsule. It is widely used in telecommunications, audio recording devices, and consumer electronics due to its compact size and reliable performance. --- ### 1. Key Technical Specifications Below are the primary electrical and physical parameters for the TOM-1545P-R: | Parameter | Specification | | :--- | :--- | | **Directional Characteristic** | Omnidirectional (picks up sound from all sides) | | **Sensitivity** | -45 ± 3 dB (0dB = 1V/Pa, 1kHz) | | **Impedance** | Low Impedance (typically < 2.2 kΩ) | | **Standard Operating Voltage** | 2.0 V DC | | **Max Operating Voltage** | 10.0 V DC | | **Current Consumption** | Max 0.5 mA | | **Frequency Range** | 20 Hz – 16,000 Hz | | **Signal-to-Noise Ratio** | > 58 dB | | **Dimensions** | Approx. 9.7mm (Diameter) x 4.5mm (Height) | | **Termination** | Through-hole Pins (P-type) | --- ### 2. Functional Components The "Electronic Parts" of this component consist of a transducer mechanism and an internal circuit: 1. **Electret Diaphragm:** A thin plastic film with a permanent electrostatic charge. When sound waves hit it, it vibrates against a stationary backplate. 2. **Backplate:** Acts as the second plate of a capacitor. The vibration of the diaphragm changes the capacitance. 3. **Internal FET (Field Effect Transistor):** * Because the impedance of the capsule is extremely high, it cannot drive a standard circuit directly. * An internal JFET acts as an **Impedance Converter**, transforming the high-impedance signal into a low-impedance signal suitable for pre-amplification. 4. **Housing:** An aluminum cylindrical can that provides structural integrity and EMI (Electromagnetic Interference) shielding. --- ### 3. Application Circuit (Example) To use the TOM-1545P-R, you must provide a bias voltage through a resistor. A capacitor is used to "block" the DC voltage and allow only the AC audio signal to pass to the amplifier. ```text Vcc (+2V to +10V) | [ R_load (2.2kΩ) ] | +----------||------> Audio Out (to Amp) | C_out (1uF) ( + ) TOM-1545P-R ( - ) | GND ``` --- ### 4. Part Number Breakdown * **TOM:** Manufacturer Series (often DB Unlimited or similar OEMs). * **1545:** Typically refers to physical dimensions or sensitivity series (15) and sensitivity level (-45dB). * **P:** Pin Type (for PCB through-hole mounting). * **R:** RoHS Compliant (Lead-free).