### TSOP11xx Series Overview The **TSOP112** (often part of the TSOP11xx series) is a miniaturized receiver for infrared remote control systems. It integrates a PIN diode and a preamplifier into a single package, acting as a complete IR sensor that filters out noise and outputs a clean digital signal. --- ### 1. Key Technical Specifications The TSOP112 is designed to respond to a specific carrier frequency. The last two digits usually represent the frequency in kHz. | Parameter | Specification | | :--- | :--- | | **Carrier Frequency** | 32.7 kHz (standard for TSOP112) | | **Supply Voltage (Vs)** | 2.7V to 5.5V | | **Supply Current** | 0.4 mA to 1.0 mA | | **Transmission Distance** | Up to 45 meters | | **Output Type** | Active Low (Digital) | | **Operating Temperature** | -25°C to +85°C | --- ### 2. Internal Functional Blocks The device is not just a photo-transistor; it contains complex circuitry to handle signal processing: 1. **PIN Diode:** Detects the infrared light. 2. **Preamplifier:** Boosts the weak signal from the diode. 3. **Automatic Gain Control (AGC):** Adjusts sensitivity to avoid saturation. 4. **Band Pass Filter:** Blocks all frequencies except the carrier frequency (32.7 kHz). 5. **Demodulator:** Removes the carrier frequency to leave only the data bits. --- ### 3. Pin Configuration The TSOP112 typically follows a standard 3-pin layout: | Pin Number | Name | Function | | :--- | :--- | :--- | | 1 | **OUT** | Data Output (Connect to Microcontroller) | | 2 | **GND** | Ground (0V) | | 3 | **Vs** | Supply Voltage (Positive) | --- ### 4. Application Circuit (Best Practice) To ensure the TSOP112 operates reliably without interference from power supply noise, a RC filter is recommended. ```c // Basic Hardware Connection [Power 5V] ---- [R1: 100 Ohm] ----+---- [Vs Pin 3] | [C1: 4.7uF Capacitor] | [Ground] -------------------------+---- [GND Pin 2] [MCU Input] <-------------------------- [OUT Pin 1] ``` --- ### 5. Key Features & Behavior * **Active Low Output:** The `OUT` pin stays HIGH when no IR signal is detected. It pulses LOW when it detects a 32.7 kHz IR burst. * **Daylight Filter:** The casing is usually dark-tinted epoxy that acts as an optical filter, blocking visible light while allowing IR light to pass. * **Compatibility:** It is compatible with almost all microcontrollers (Arduino, ESP32, PIC) because it provides a TTL/CMOS logic level output.