## Overview of the TSOP22 Series The **TSOP22** series (often referred to as TSOP22xx) is a family of miniaturized IR receiver modules designed for infrared remote control systems. These components integrate a PIN diode, a preamplifier, and a bandpass filter into a single package. ### 1. Internal Block Diagram The internal circuitry of a TSOP22 module is sophisticated, designed to handle noisy environments. | Component | Function | | :--- | :--- | | **PIN Diode** | Converts incoming Infrared light into electrical signals. | | **Preamplifier** | Amplifies the weak electrical signal from the diode. | | **AGC (Automatic Gain Control)** | Adjusts the gain to handle different light intensities and suppress noise. | | **Band Pass Filter** | Filters out signals not matching the specific carrier frequency (e.g., 38kHz). | | **Demodulator** | Removes the carrier wave to output the original data pulses. | --- ### 2. Pin Configuration The TSOP22 usually features a three-pin arrangement. Note that pinouts can vary slightly by manufacturer, but the standard configuration is: | Pin Number | Name | Description | | :--- | :--- | :--- | | 1 | **OUT** | Data Output; Logic LOW when IR is detected. | | 2 | **GND** | Ground / Common | | 3 | **Vs** | Supply Voltage (Typically 2.5V to 5.5V). | --- ### 3. Key Specifications The following table summarizes the typical electrical characteristics for the TSOP22 series: | Parameter | Value | | :--- | :--- | | **Supply Voltage (Vs)** | 2.5 V to 5.5 V | | **Supply Current (Is)** | ~0.7 mA | | **Carrier Frequency ($f_o$)** | 30 kHz to 56 kHz (Specific to model, e.g., TSOP2238 = 38kHz) | | **Transmission Distance** | Up to 45 meters | | **Directivity** | Half angle: $\pm$ 45° | --- ### 4. How it Works (Logic Level) The TSOP22 operates on **Active Low** logic. 1. **Idle State:** When no infrared signal is detected at the specific carrier frequency, the `OUT` pin stays **HIGH** (equal to $V_s$). 2. **Detection State:** When the sensor detects an IR burst at the correct frequency, the internal transistor conducts, pulling the `OUT` pin **LOW** (0V). ### 5. Application Circuit To ensure stability, a simple RC filter is recommended for the power supply pin to reduce ripple noise. ```cpp // Typical Arduino connection logic int irPin = 2; // Connected to TSOP22 OUT pin void setup() { pinMode(irPin, INPUT); Serial.begin(9600); } void loop() { int val = digitalRead(irPin); if (val == LOW) { Serial.println("IR Signal Detected!"); } } ``` ---