## Overview of the TSSP57038 The **TSSP57038** is a compact infrared (IR) sensor module designed for proximity and reflective sensor applications. Unlike standard IR receivers used for remote controls (which look for specific data protocols), the TSSP series is optimized for **fixed-gain** applications like object detection and light barriers. --- ### 1. Key Technical Specifications The following table highlights the critical electronic parameters of the TSSP57038: | Parameter | Specification | | :--- | :--- | | **Carrier Frequency** | 38 kHz (most common variant) | | **Supply Voltage (Vs)** | 2.5 V to 5.5 V | | **Supply Current (Is)** | 0.7 mA (typical) | | **Transmission Distance** | Up to 8 meters (as a light barrier) | | **Directivity** | Half angle: ± 45° | | **Output Type** | Active Low (CMOS/TTL compatible) | --- ### 2. Internal Electronic Architecture The TSSP57038 is more than just a photodiode; it is an Integrated Circuit (IC) that includes several stages: 1. **Photodetector:** A high-sensitivity PIN photodiode that converts IR light into an electrical signal. 2. **Preamplifier:** Boosts the weak signal from the photodiode. 3. **Automatic Gain Control (AGC):** Unlike the TSOP series (which adjusts gain dynamically), the TSSP series has a **fixed gain**. This makes it more predictable for detecting the presence/absence of a signal rather than decoding data. 4. **Band Pass Filter:** Specifically tuned to 38 kHz to filter out ambient light noise (like sunlight or fluorescent lamps). 5. **Demodulator:** Removes the 38 kHz carrier and provides a simple high/low logic signal to the output pin. --- ### 3. Pin Configuration The device usually comes in a 3-pin surface-mount package (SMD): * **Pin 1 (OUT):** Logic output. Connects to a microcontroller GPIO. * **Pin 2 (GND):** Ground. * **Pin 3 (Vs):** Power supply (2.5V - 5.5V). --- ### 4. Typical Application Circuit To ensure stable operation, a simple RC filter is recommended for the power supply to suppress noise. ```cpp // Logic Diagram [ Power Supply +5V ] | [ R1: 100 Ohm ] |----------[ Pin 3: Vs ] [ C1: 4.7uF ] | | [ TSSP57038 ] [ GND ]----------[ Pin 2: GND ] | [ Pin 1: OUT ] ----> [ Microcontroller ] ``` ### 5. Why use TSSP instead of TSOP? * **TSOP Series:** Designed for Remote Controls. If it receives a continuous 38kHz signal, it treats it as noise and shuts down the output. * **TSSP Series:** Designed for Proximity. It can handle a **continuous carrier signal** indefinitely without the output turning off. This is essential for safety light curtains and optical switches. ---