TCST2103 Transmissive Optical Sensor with Phototransistor Output DIP-4

TCST2103 Transmissive Optical Sensor is a reliable and accurate component widely used for detecting the presence, position, and speed of objects. This device works by integrating an infrared light-emitting diode (LED) and a phototransistor across a gap, creating a highly effective optical switch. When an opaque object passes through the slot, it interrupts the infrared beam, causing the phototransistor to switch its output state. Engineers and makers choose the TCST2103 for its robust, plastic-molded housing, which shields the sensitive components from ambient light interference, ensuring high reliability. This sensor provides a simple, non-contact method for digital signaling in a compact DIP-4 package, making it perfect for counting rotations, monitoring limits, or determining motion direction.

Key Features:

• Non-Contact Sensing: Detects objects without physical wear and tear, providing long life and high reliability in demanding environments.
• Phototransistor Output: The output is a phototransistor, which allows for simple interfacing with microcontrollers or logic circuits using a pull-up resistor.
• Infrared Emitter & Detector: Uses an integrated 950 nm infrared LED and silicon phototransistor pair for efficient and reliable beam detection.
• Wide Slot Width: Features a generous gap width, accommodating thicker disks or flags commonly found in encoders and limit switches.
• High Ambient Light Rejection: The opaque plastic housing minimizes interference from external light sources, improving detection accuracy.
• Standard DIP-4 Package: The through-hole form factor is easy to mount on PCBs and prototype boards for quick development.

Technical Specifications:

• Output Type: Phototransistor
• Detector Type: Silicon Phototransistor
• LED Wavelength: 950 nm (Infrared)
• Maximum Collector Current (I_C): 100 mA
• Maximum Collector-Emitter Voltage (V_CEO): 30 V
• Operating Temperature Range: -40 °C to +85 °C
• Gap Width: 3.0 mm

Mechanical Specifications:

• Mounting: Through-Hole (DIP)
• Housing Material: Opaque, molded plastic (Polyamide)
• Leads: Standard solderable pins.

Dimensions:

• Body Length: ~8.7 mm
• Body Width: ~6.0 mm
• Slot Width (Gap): 3.0 mm
• Pin Pitch (Spacing between pins): 2.54 mm (0.1 in)

Pinout and Wiring:

• Pin 1 (LED Anode): Connect to the positive power supply through a current-limiting resistor (typically 150-330 Ω for 5V).
• Pin 2 (LED Cathode): Connect to ground (GND).
• Pin 3 (Collector): Connect to the positive supply (VCC) through a pull-up resistor (typically 1 kΩ to 10 kΩ). This is the digital signal output.
• Pin 4 (Emitter): Connect to ground (GND).
• Wiring Note: Always use a current-limiting resistor on the LED side (Pins 1 and 2) to prevent burnout. The output signal (Pin 3) goes HIGH when the light path is interrupted, and LOW when the light path is clear (using a pull-up resistor).

Datasheet Reference:

• Download Datasheet

Commonly Used in:

• Motor Control: Used in DC motor shafts to sense rotation speed and direction.
• Printers and Scanners: Functions as a limit switch to determine the home or end position of a carriage or paper path.
• Vending Machines: Monitors coin passage or ensures product delivery mechanisms are functioning correctly.

Applications:

• Rotary Encoder Systems: Count pulses from a perforated wheel to measure speed or angle.
• Object Sensing: Simple presence/absence detection on assembly lines or in robotics.
• Speed Measurement: Calculate RPM by measuring the frequency of interruptions from a spinning disk.
• Paper/Card Detection: Check the flow of paper in documentation devices.

Equivalent Models:

• H22A1: A common alternative with a similar phototransistor output and slot design.
• QRD1114: A reflective optical sensor, often used when an object cannot pass through a slot.

Package Includes:

• 1 x TCST2103 Transmissive Optical Sensor with Phototransistor Output DIP-4