Ambient light sensing components · Photoresistors (LDR), phototransistors and digital ambient light sensor ICs, spectral response against the human eye, lux range and resolution, response time and interface
A light sensor converts the light falling on it into an electrical signal so a device can measure ambient brightness or switch on light level, for example to dim a display, switch street or garden lights, or log illuminance in an environmental monitor. Ask three things first: which sensing type fits (photoresistor, phototransistor or digital ambient light sensor), whether its spectral response must follow the eye's or may include infrared, and what lux range, resolution, response time and output the design needs.
Light-sensing components and small modules for ambient light measurement and light-level switching: cadmium-sulphide photoresistors (LDRs), phototransistors, digital ambient light sensor ICs and wireless ambient light sensor modules. Pyranometers, colour sensors, image sensors, flame and PIR detectors are outside this page except where compared.
01
Senba Sensing lists photoresistors (light-dependent resistors) in 5 mm and other sizes; its 5 mm GL55 series data give, for example, GL5528 at 150 V maximum voltage, 100 mW maximum power, −30 to +70 °C, spectral peak 540 nm, 10–20 kΩ under 10 lux, 1 MΩ dark resistance and 20 ms rise and 30 ms decay time, and GL5516 at 5–10 kΩ under 10 lux and 0.5 MΩ dark. It defines the γ value as the logarithm of the ratio of resistance at 10 lux to resistance at 100 lux, measured with a 2,856 K standard light source. [1]
Senba also lists visible-light phototransistors such as the LS06-S, with a peak wavelength of 850 nm across 450–1,050 nm, dark current about 0.2 µA at 5 V and 0 lux, and 10 µs opening and 15 µs closing time. [2] Editorial note: a sensor whose response peaks in the near infrared will read differently from the eye under light sources with different infrared content; where readings must track perceived brightness, ask for the spectral response curve.
Editorial calculation: in a 5 V divider with a 10 kΩ fixed resistor, a GL5528 at 10–20 kΩ under 10 lux gives 5 × 10 / (10 + 10 to 20) ≈ 2.5 to 1.7 V across the fixed resistor, and about 0.05 V in the dark at 1 MΩ; the spread at 10 lux shows why switching thresholds need calibration or a tighter resistance grade. [1]
Give the supplier the application (display dimming, light switching, environmental logging), lux range and resolution needed, spectral requirement (eye-matched or broadband), response time, supply voltage, output (resistance, current, analogue voltage, I²C, wireless), package or housing, window or lens transmittance, operating temperature, ingress protection, and compliance needs.
02
Vishay's VEML7700 datasheet describes a digital ambient light sensor combining a photodiode, low-noise amplifier and 16-bit A/D converter with an I²C interface, measuring from 0 lux to about 140,000 lux with resolution down to 0.0042 lux per count, with 100 Hz and 120 Hz flicker rejection and temperature compensation; its spectral-response figure plots the sensor's response against the eye-response curve V(λ). It lists a supply of 2.5–3.6 V, an operating range of −25 to +85 °C and a 6.8 × 2.35 × 3.0 mm package, for uses such as backlight dimming. [3]
Editorial calculation: at 0.0042 lux per count a 16-bit result (65,535 counts) spans about 275 lux, so measuring up to 140,000 lux uses coarser resolution settings; ask which range and resolution apply at the light levels you must measure. [3]
Minew lists its MSA01 ambient light sensor as a wireless (Bluetooth) device using a photodiode to measure illuminance over 1–54,388 lux, broadcasting data at configurable intervals. [4] Editorial note: for a module or wireless sensor, ask which sensing element it uses, its calibration and accuracy, and its reporting interval.
03
Senba lists photoresistors and phototransistors with PIR sensors, Haiwang CdS photoresistors with PIR sensors and Fresnel lenses, and Minew the MSA01 wireless ambient light sensor.
Ask each of them for spectral response, resistance or current at stated lux, dark value, response time, temperature range and compliance documents.
04
The photoresistor and phototransistor rows come from Senba's data, the photodiode, converter and window rows from Vishay's VEML7700 datasheet, and the radio housing row from Minew's MSA01 listing.
| Element | Role | Fix in the order |
|---|---|---|
| Photoresistor (CdS) | Resistance falls with light. [1] | R at 10 lux; dark R; γ. |
| Phototransistor | Current rises with light. [2] | Peak λ; dark current. |
| Photodiode and amplifier (ALS IC) | Eye-weighted signal. [3] | Spectral match. |
| A/D converter and interface | Digital lux output. [3] | Bits; I²C address. |
| Window or lens | Admits light. [3] | Transmittance. |
| Module housing and radio | Wireless reporting. [4] | Interval; protection. |
05
The values come from parts of different types — Senba's GL55 photoresistors and LS06-S phototransistor, the VEML7700 IC and the MSA01 module — so compare each figure only with a sensor of the same type.
| Field | What it means and published values | Ask the supplier for |
|---|---|---|
| Supply Voltage (V) | E.g. 2.5–3.6 V ALS IC; 150 V max LDR. [3] [1] | Range. |
| Output Type | Resistance, current, I²C. [1] [3] | Interface. |
| Spectral Range (nm) | E.g. LDR peak 540; phototransistor 450–1,050. [1] [2] | Response curve. |
| Illuminance Range (lux) | E.g. 0–140,000 lux ALS. [3] | Range at resolution. |
| Accuracy (%) | E.g. ±15% for the MSA01 module. [4] | Method; light source. |
| Resolution (lux) | E.g. 0.0042 lux per count. [3] | Setting used. |
| Response Time (ms) | E.g. 20/30 ms LDR; 0.010/0.015 ms (10/15 µs) phototransistor. [1] [2] | Value. |
| Operating Temperature (°C) | E.g. −30 to +70 LDR; −25 to +85 ALS; −20 to +60 MSA01 module. [1] [3] [4] | Range. |
| Storage Temperature (°C) | E.g. −25 to +85 °C ALS. [3] | Range. |
| Humidity Range (%) | Module or outdoor use. | Range. |
| Ingress Protection | Module housing. | Rating. |
| Package Type | E.g. 5 mm LDR; 6.8 × 2.35 × 3.0 mm SMD. [1] [3] | Package; footprint. |
| Weight (g) | E.g. 17 g for the MSA01 module. [4] | Weight. |
06
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Application: [dimming; switching; logging] Light: [lux range; resolution; light sources] Spectral: [eye-matched or broadband] Type: [LDR; phototransistor; ALS IC; module] Output: [resistance; current; I²C; wireless] Environment: [temperature; humidity; IP] Documents: [datasheet; response curve; compliance]
3 companies list this product among what they make. Company figures are quoted from each company's own website; every card states where the relationship came from.
Lists visible-light sensors including photoresistors and phototransistors with PIR sensors.
Product scope checked 2026-10-11
Lists CdS photoresistors (LDR light sensors) with PIR sensors and Fresnel lenses.
Product scope checked 2026-10-11
Lists an MSA01 wireless ambient light sensor among IoT devices.
Product scope checked 2026-10-11
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
A photoresistor's resistance falls with light (Senba's GL5528: 10–20 kΩ at 10 lux, 1 MΩ dark); a phototransistor passes more current with light and switches in microseconds. [1] [2]
An ambient light sensor whose spectral response follows the eye curve V(λ), as Vishay plots for the VEML7700; phototransistors peaking at 850 nm also respond to near infrared. [3] [2]
The VEML7700 measures from 0 to about 140,000 lux, with resolution down to 0.0042 lux per count. [3]
Sources checked 2026-10-11. Vishay's datasheet, Senba's pages and Minew's MSA01 page describe their own products; no single standard covers all light sensor types.
Ask for use case, specification boundaries, supplier type, and RFQ preparation information for this product.
Compare manufacturer profiles with relevant product and process capability.