Overview

The TEMT6000 is an analog silicon NPN epitaxial planar phototransistor manufactured by Vishay Semiconductors. Mounted on a compact 3-pin breakout module, it detects ambient light levels and outputs an analog voltage proportional to illuminance.

Designed specifically to adapt to the human eye's spectral sensitivity curve (photopic vision response peaking at 570 nm570\text{ nm}), the TEMT6000 inhibits infrared (IR) wavelengths, serving as an eco-friendly, RoHS-compliant replacement for toxic Cadmium Sulfide (CdS) photoresistors (LDRs) in display backlight control, daylight harvesting, and automotive automatic headlamp triggers.

Quick reference

Operating voltage (VCC)3.3 V to 5.0 V DC
Output signalLinear Analog Voltage (0 V to VCCV_{CC})
Peak spectral response570 nm (human photopic vision curve)
Half-sensitivity angle±60∘\pm 60^\circ
Collector current (ICAI_{CA})50 μA50\ \mu\text{A} at 100 Lux (VCE=5.0VV_{CE} = 5.0\text{V})
Dark current (ICEOI_{CEO})2 nA2\text{ nA} typical (0 Lux0\text{ Lux})
Onboard load resistor10 kΩ10\text{ k}\Omega pull-down resistor on breakout module

Pinout

Standard 3-pin 0.1" (2.54 mm) header:

PinNameTypeDescription
1VCC / VPowerSupply voltage (+3.3 V to +5.0 V DC)
2GND / GPowerGround (0 V)
3OUT / SAnalog OutputAnalog voltage output proportional to ambient light

Specifications

ParameterSymbolMinTypMaxUnitConditions
Supply VoltageVCCV_{CC}3.35.05.5VDC
Collector Light CurrentICAI_{CA}2050100µAEv=100 LuxE_v = 100\text{ Lux}, VCE=5.0VV_{CE} = 5.0\text{V}
Dark CurrentICEOI_{CEO}—250nAEv=0 LuxE_v = 0\text{ Lux}, VCE=5.0VV_{CE} = 5.0\text{V}
Wavelength of Peak Sensitivityλp\lambda_p—570—nmHuman eye sensitivity curve
Range of Spectral Bandwidthλ0.5\lambda_{0.5}440—800nmHalf-sensitivity range
Rise / Fall Timetr/tft_r / t_f—15 / 15—µsRL=1 kΩ,IC=1 mAR_L = 1\text{ k}\Omega, I_C = 1\text{ mA}

Circuit Principle & Lux Approximation

On standard breakout boards, the TEMT6000 phototransistor collector connects to VCC, and the emitter connects to GND through a 10 kΩ10\text{ k}\Omega pull-down resistor (RLR_L). The OUT voltage is measured across RLR_L:

VOUT=ICA×RL=ICA×10,000 ΩV_{OUT} = I_{CA} \times R_L = I_{CA} \times 10,000\ \Omega

At 100 Lux100\text{ Lux}, ICA≈50 μA  ⟹  VOUT≈50 μA×10 kΩ=0.5VI_{CA} \approx 50\ \mu\text{A} \implies V_{OUT} \approx 50\ \mu\text{A} \times 10\text{ k}\Omega = 0.5\text{V}.

Approximate Lux calculation formula:

Illuminance (Lux)=VOUTVCC×1000(or Lux=ADCrawADCmax×1000)\text{Illuminance (Lux)} = \frac{V_{OUT}}{V_{CC}} \times 1000 \quad \text{(or } \text{Lux} = \frac{ADC_{raw}}{ADC_{max}} \times 1000 \text{)}

Wiring

TEMT6000 Pin→Arduino UnoESP32Notes
VCC5V / 3.3V3.3VMatch supply to ADC reference voltage
GNDGNDGNDSystem ground
OUTAnalog Pin A0VP / GPIO36 (ADC1)Linear analog output

Example

cpp
const int lightSensorPin = A0;

void setup() {
  Serial.begin(9600);
}

void loop() {
  int rawADC = analogRead(lightSensorPin);
  float voltage = (rawADC / 1023.0) * 5.0;
  
  // Approximate Lux calculation
  float lux = (voltage / 5.0) * 1000.0;

  Serial.print("Raw ADC: "); Serial.print(rawADC);
  Serial.print(" | Voltage: "); Serial.print(voltage); Serial.print(" V");
  Serial.print(" | Lux: "); Serial.println(lux);

  delay(500);
}

Common mistakes

  • Conflating phototransistor behavior with CdS LDRs: CdS photoresistors decrease resistance with light (requiring a voltage divider circuit); the TEMT6000 module outputs a direct positive voltage that increases linearly with light.
  • Expecting precision lux meter accuracy: The TEMT6000 provides excellent relative illuminance sensing, but component tolerances (±50%\pm 50\% on ICAI_{CA}) mean uncalibrated Lux values are approximations.

Notes

  • TEMT6000 vs LDR (CdS): CdS photoresistors are banned in many countries under RoHS environmental regulations due to cadmium content; TEMT6000 is RoHS compliant and IR-filtered.

Assets & downloads