The **TSOP772** is a miniaturized receiver module designed for infrared (IR) remote control systems. It integrates a PIN diode and a preamplifier into a single lead frame, encapsulated in an epoxy package that acts as an IR filter. --- ### 1. Key Features and Specifications The TSOP772 belongs to the high-performance IR receiver family, characterized by its immunity to ambient light and electrical noise. | Parameter | Specification | | :--- | :--- | | **Supply Voltage ($V_S$)** | 2.5 V to 5.5 V | | **Supply Current ($I_S$)** | 0.7 mA (typical) | | **Carrier Frequency ($f_0$)** | 30 kHz to 56 kHz (model dependent) | | **Transmission Distance** | Up to 45 meters | | **Directivity** | $\pm$ 45 degrees (half-angle) | | **Output Type** | Active Low (CMOS/TTL compatible) | --- ### 2. Internal Functional Blocks The device is more than just a light sensor; it is a complete signal processing circuit. 1. **PIN Photodiode:** Converts IR light pulses into electrical current. 2. **Preamplifier:** Amplifies the weak current from the photodiode. 3. **Automatic Gain Control (AGC):** Adjusts sensitivity to suppress noise from fluorescent lamps or sunlight. 4. **Band Pass Filter:** Specifically tuned to the carrier frequency (e.g., 38kHz) to ignore other light sources. 5. **Demodulator:** Removes the carrier wave and outputs the clean data envelope. --- ### 3. Pin Configuration The TSOP772 typically uses a 3-pin surface-mount or through-hole configuration: | Pin Number | Name | Function | | :--- | :--- | :--- | | 1 | **OUT** | Demodulated data output (normally High, goes Low on signal) | | 2 | **GND** | Ground connection | | 3 | **$V_S$** | Power supply (2.5V - 5.5V) | --- ### 4. Application Circuit To ensure stability, it is recommended to add an RC filter to the supply line to suppress power supply ripples. ```cpp // Typical Schematic Representation // [VS] ----[ Resistor 100Ω ]----+---- (Pin 3: Vs) // | // [Capacitor 4.7µF] // | // [GND] ------------------------+---- (Pin 2: GND) // // [MCU Input] <----------------------- (Pin 1: OUT) ``` --- ### 5. Selection Guide (Frequency Variants) The "772" series is followed by a two-digit code indicating the carrier frequency. Choosing the correct frequency to match your IR transmitter is critical for range. * **TSOP77230:** 30 kHz * **TSOP77236:** 36 kHz * **TSOP77238:** 38 kHz (Most common for TV remotes) * **TSOP77240:** 40 kHz * **TSOP77256:** 56 kHz