## Overview of the TSSP770 Series The **TSSP770** is a compact infrared (IR) sensor module designed for proximity and object detection. Unlike standard IR receivers used in TV remotes (which look for specific data protocols), the TSSP770 is optimized for **sensor applications** such as light barriers, reflective sensors, and proximity sensing. It is manufactured by Vishay Semiconductors and belongs to the **TSSP** (Sensing) family. --- ### 1. Key Internal Components The TSSP770 integrates several electronic stages into a single 4-pin or 3-pin surface-mount package (Heimdall). | Component | Function | | :--- | :--- | | **Photodiode** | Converts incoming Infrared light into a tiny electrical current. | | **Preamplifier** | Amplifies the weak signal from the photodiode. | | **Band Pass Filter** | Filters out light at frequencies other than the carrier frequency (e.g., 38 kHz or 56 kHz). | | **Demodulator** | Processes the signal to determine if the carrier frequency is present. | | **Output Driver** | Provides a digital logic signal (Active Low) to the microcontroller. | --- ### 2. Technical Specifications The device is characterized by its high sensitivity and low power consumption. * **Supply Voltage ($V_S$):** 2.5 V to 5.5 V * **Supply Current ($I_S$):** Typically 0.7 mA (very low power). * **Carrier Frequencies ($f_{o}$):** Available in versions for 38 kHz and 56 kHz. * **Output Type:** Open collector (Active Low). * **Operating Temperature:** -25 °C to +85 °C. --- ### 3. Pin Configuration (Typical) The TSSP770 usually comes in a surface-mount package with the following pinout: 1. **OUT:** Data output; connects to a microcontroller GPIO. 2. **GND:** Ground. 3. **$V_S$:** Power supply. --- ### 4. How It Differs From Standard IR Receivers It is important to distinguish the TSSP770 from standard IR receivers (like the TSOP series): | Feature | TSOP Series (Remote Control) | TSSP770 (Sensing) | | :--- | :--- | :--- | | **Gain Control** | High (Automatic Gain Control) | Fixed/Stable Gain | | **Burst Length** | Requires specific burst gaps/lengths | Can handle continuous bursts | | **Primary Use** | Receiving data (Remote Control) | Proximity/Distance sensing | --- ### 5. Application Circuit To use the TSSP770, you typically need a current-limiting resistor for the IR LED and a decoupling capacitor for the sensor. ```c // Basic Logic Flow 1. Microcontroller pulses an IR LED at 38kHz. 2. If an object is present, IR light reflects into TSSP770. 3. TSSP770 pin 'OUT' goes LOW. 4. Microcontroller detects LOW signal = Object Detected. ``` ---