Overview

The TCRT5000 is a reflective optical sensor manufactured by Vishay Intertechnology. It houses a 950 nm infrared emitting diode (LED) and an NPN phototransistor detector side-by-side in a blue daylight-blocking plastic casing.

When an object or reflective surface passes in front of the sensor (0.2 mm to 15 mm0.2\text{ mm to }15\text{ mm} distance), infrared light from the LED bounces back into the phototransistor, driving it into conduction. It is universally used in line-following robot cars (detecting black electrical tape on white floors), shaft encoders, and paper-edge detection.

Quick reference

Module VCC3.3 V to 5.0 V DC
Peak Operating Distance2.5 mm (0.2 mm to 15 mm0.2\text{ mm to }15\text{ mm} total range)
IR Emitter Wavelength950 nm
IR Emitter Forward Voltage1.25 V (requires series current limiting resistor 180 Ω180\text{ }\Omega to 220 Ω220\text{ }\Omega on 5V)
Phototransistor Max Collector Current100 mA
Daylight Blocking FilterIntegrated blue optical filter blocks ambient visible light
Breakout OutputsAnalog Voltage (AO) / Digital Threshold (DO via LM393)

Pinout

Standard 4-Pin Breakout PCB Module

PinNameTypeDescription
1VCCPowerSupply voltage (+3.3 V to +5.0 V DC)
2GNDPowerGround (0 V)
3DODigital OutputDigital threshold output (HIGH over non-reflective black surface, LOW over reflective white surface)
4AOAnalog OutputAnalog voltage output proportional to reflected IR light intensity

Component Level Pinout (TCRT5000 Package)

  • Anode (A) / Cathode (K): Blue housing IR LED connections.
  • Collector (C) / Emitter (E): Black housing NPN Phototransistor connections.

Specifications

ParameterSymbolMinTypMaxUnitConditions
Emitter Forward VoltageVFV_F1.01.251.5VIF=60 mAI_F = 60\text{ mA}
Emitter Forward CurrentIFI_F—3060mAContinuous DC
Collector Light CurrentICAI_{CA}0.21.0—mAVCE=5 VV_{CE} = 5\text{ V}, D=2.5 mmD = 2.5\text{ mm}, Kodak neutral card
Peak Sensing Distancedoptd_{opt}—2.5—mmOptimum reflection distance
Day Filter Wavelengthλp\lambda_p—950—nmPeak spectral sensitivity
Operating TemperatureTambT_{amb}-25—85°C

Reflectivity Principles (Line Following)

Surface TypeIR Light ReflectionPhototransistor StateAnalog Output Voltage (AO)Digital Output (DO)
White / Reflective SurfaceHigh ReflectionConducting (ON)LOW (≈0.1 V\approx 0.1\text{ V} – 0.5 V0.5\text{ V})LOW
Black / Non-Reflective TapeLow / AbsorbedOff (Cutoff)HIGH (≈VCC\approx V_{CC})HIGH
No Surface (Air Gap)Zero ReflectionOff (Cutoff)HIGH (≈VCC\approx V_{CC})HIGH

Wiring

TCRT5000 Module Pin→Microcontroller (Arduino Uno / ESP32)
VCC5V (or 3.3V)
GNDGND
DODigital GPIO Pin (e.g. D2 for line detection)
AOAnalog Input Pin A0 (optional for fine reflectivity gradient)

Common mistakes

  • Mounting too far from the ground: The optimum detection height for line-following robots is 2 mm to 3 mm2\text{ mm to }3\text{ mm} above the surface. Mounting the sensor >15 mm>15\text{ mm} high results in total loss of reflection signal.
  • Connecting bare TCRT5000 component without resistors: Connecting the IR LED directly to 5V without a 220 Ω220\text{ }\Omega series resistor burns out the IR LED immediately.
  • Ambient light interference: Direct sunlight contains strong 950 nm IR radiation. Shield the sensor underside from direct outdoor sunlight.

Notes

  • The onboard LM393 potentiometer adjusts the switching threshold sensitivity between black tape and white background.

Assets & downloads