Texas Instruments OPT4001/OPT4001-Q1 Digital Ambient Light Sensor

Texas Instruments OPT4001/OPT4001-Q1 Digital Ambient Light Sensor (ALS) is a light-to-digital sensor that measures the intensity of visible light. The sensor's spectral response tightly matches the human eye's photopic response. A specially engineered filter on the device rejects near-infrared components from the common light sources to measure accurate light intensity.

The OPT4001/OPT4001-Q1 is a single-chip lux meter capable of accurately measuring the intensity of light seen by the human eye regardless of the light source. The output of OPT4001 is semi-logarithmic with nine binary logarithmic full-scale light ranges along with highly linear response within each range, bringing the capability to measure from 312.5µlux to 83klux. This capability allows the light sensor to have a 28-bit effective dynamic range. Users do not have to select appropriate gain settings based on light levels with built-in automatic full-scale range selection logic.

The strong near-infrared rejection also aids in maintaining high accuracy despite placing the sensor under the dark glass, which is a common requirement from the industrial design of end products due to aesthetics. The OPT4001/OPT4001-Q1 is designed for systems that require light-level detection to enhance user experience and typically replace low-accuracy photodiodes, photo-resistors, and other ambient light sensors with underwhelming human eye matching and near infra-red rejection.

The Texas Instruments OPT4001/OPT4001-Q1 can be configured to operate with light conversion times from 600µs to 800ms in 12 steps, providing system flexibility based on application needs. Conversion time includes the light integration time and ADC conversion time. The resolution of the measurement is determined by the light intensity and the integration time, effectively bringing in the capability to measure down to 312.5µlux of light intensity changes.

The digital operation is flexible for system integration. Measurements can be either continuous or triggered in one-shots with register write. The digital output is reported over an I2C- and SMBus-compatible, two-wire serial interface. An internal FIFO on output registers and burst mode I2C support helps minimize interrupts and processing power required by the I2C controller. The low power consumption and low power-supply voltage capability of the OPT4001/OPT4001-Q1 help enhance the battery life of battery-powered systems. The OPT4001-Q1 devices are AEC-Q100 qualified for automotive applications.


  • High precision, high-speed light-to-digital conversion over high-speed I2C interface
  • Precision optical filtering to closely match human eye with excellent near-infrared (IR) rejection
  • Semi-logarithmic output with nine binary logarithmic full-scale light range and highly linear response within a range
  • Built-in automatic full-scale light range selection logic, which switches measurement range based on input light condition with excellent gain matching between ranges
  • 28 bits of effective dynamic range from 312.5µlux to 83klux
  • 12 configurable conversion times from 600µs to 800ms suitable for a wide variety of high speed and high precision applications
  • High precision measurements. For example, up to 40mlux resolution at 6.5ms and 2.5mlux at 100ms conversion times
  • Internal FIFO on output registers with burst readout
  • Low operating current 30µA with ultra-low power standby 2µA
  • –40°C to +85°C operating temperature range
  • 5.5V Tolerant I/O pins
  • Small-form factor
    • 0.84mm x 1.05mm x 0.226mm PicoStar™ package


  • Display backlight controls for
    • Smartwatch
    • Wearable electronics
    • Health fitness bands

Functional Block Diagram

Block Diagram - Texas Instruments OPT4001/OPT4001-Q1 Digital Ambient Light Sensor
Published: 2022-03-15 | Updated: 2023-09-01