A sensor that approximates the perception of the human eye-ambient light sensor
Approximate eye, ambient light sensor
The ambient light sensor is a sensor that outputs electrical signals in real time by sensing the surrounding light intensity. Ambient light sensors are used in consumer electronics, automotive electronics, industrial control and other fields. For example, the top of smart phones and tablet computers will be equipped with ambient light sensors. The ambient light sensor senses the light intensity and realizes real-time control of screen brightness. Reduce the power consumption of the equipment, extend the service life of the equipment, and protect the eyes.

Source: TI official website
Development Trend of Ambient Light Sensor

With the increasing use of ambient light sensors in the field of consumer electronics, consumer electronics is also moving towards miniaturization and portability. Therefore, ambient light sensors must also move towards high integration (miniaturization), low power consumption, intelligence, etc. Direction development.

High integration (miniaturization) can reduce the layout of peripheral circuits, reduce the amount of components, and to a certain extent can realize the versatility of the sensor, reduce the BOM cost, and reduce the volume of the sensor.

Low power consumption. For consumer electronics, the use of low power consumption electronic components is a long-standing pursuit, which can effectively extend the battery life of the device and achieve energy conservation and environmental protection.

Intelligentization. At present, many chips and sensors integrate AI algorithms, DSP processors, etc., to further improve data processing capabilities and help improve performance.

The application of ambient light sensors is very wide. At present, the market demand is constantly infiltrating into smart home appliances, Internet of Things and other fields, and the market demand is also showing a rapid growth trend. With the continuous expansion of application fields, the development prospects of ambient light sensors are very clear.

At present, AMS, TI, Vishay, ROHM and other leading companies in the field of foreign semiconductors have developed ambient light sensors and have been applied by terminal manufacturers.

AMS TMD2712 ambient light sensor and proximity sensor integrated module

AMS has profound knowledge in the field of optics and has advanced optical solutions. Whether it is technology or production capacity, AMS has obvious advantages in the field of sensors. Today, AMS's sensor business occupies a leading position in the field of consumer electronics, and is committed to developing more integrated and smaller sensors to seize market share and consolidate its leading position.

TMD2712 frame diagram Source: AMS official website

The TMD2712 module is a three-in-one highly integrated sensor, which integrates an ambient light sensor, a proximity light sensor and an infrared VCSEL transmitter, and the volume is only 1mm*2mm*0.5mm under the highly integrated all-in-one, which can be applied In electronic products with stricter requirements on the volume of the sensor, the launch of this sensor set a new record for the size of the sensor.

The proximity detection of TMD2712 is realized by the infrared VCSEL transmitter emitting infrared rays, and then the photodiode detects the reflected light. TMD2712 provides two ambient light sensing channels for the ambient light sensor. Through these two channels, the surrounding ambient light can be accurately measured, and the light radiation intensity can be calculated to output electrical signals.

The TMD2712 sensor has a power supply voltage of 1.8V, a standby power consumption of 0.7µA, a proximity detection distance of 15cm, and can withstand a working temperature range of -30℃ to 85℃. It adopts a 6 Pin OLGA package.

TI OPT3004 High Sensitivity Ambient Light Sensor

According to TI's official display, TI's ambient light sensor can optimize cost, simulate human eye response, and be thin and light. Its application range covers consumer electronics, household appliances, automotive electronics and other fields.

OPT3004 frame diagram Source: TI official website

OPT3004 is an ambient light sensor for measuring visible light. It can block infrared light with a blocking rate of 99% and has a sensitive spectral response. The spectral response curve of the sensor can be similar to the response curve of the human eye, and the measurement accuracy of visible light is not affected by the light intensity.

Spectral response: OPT3004 and human eye Source: TI official website

OPT3004 has the function of adaptively adjusting the range, the range covers 0.01~83k lux, and can complete the measurement of light intensity within the effective dynamic range of 23 bits. OPT3004 ambient light sensor has two measurement working modes, one is continuous work, and the other is intermittent work. In order to reduce the power consumption of the system, the processor can be in a sleep state while the sensor is reporting. OPT3004 can be connected to a wide piezoelectric network from 1.6V to 3.6V, and its operating temperature range is between -40°C and +85°C. It uses a small USON package of 2mm*2mm*0.65mm. This ambient light sensor can be applied to display backlight control, lighting control systems, etc.

Vishay's highly sensitive ambient light sensor

Vishay's environmental light sensor, in order to improve the sensor's sensitivity to light, usually Vishay will use the unique Filtron technology in the development of the light sensor, as far as possible to match the spectral response of the sensor with the human eye, and improve the product performance.

VEML6031X00 frame diagram Source: Vishay

VEML6031X00 is a high-precision, high-sensitivity ambient light sensor from Vishay. The sensor can be used in consumer electronics and automotive electronics. It has passed the automotive AECQ100 standard certification. The spectral sensitivity of VEML6031X00 is close to the level of the human eye, and the measurement coverage is The maximum is 0.01~228k lux, which is much higher than TI's OPT3004. The sensor adopts I2C as the communication bus interface. By configuring the I2C interface, the sensor can work continuously or intermittently.

The accuracy of VEML6031X00 is 0.0034lx. The use of a lens with lower visibility can improve the accuracy of light source detection. At the same time, the built-in infrared channel of the sensor can perform light intensity detection and sensitivity adjustment, and complete error compensation. The voltage input range of VEML6031X00 is between 2.5V and 3.6V, which can adapt to a wide temperature working environment from -40°C to 110°C, meeting the requirements of automotive use. The sensor has a power consumption of 0.5μA in standby mode and uses a small package of 2.67 mmx*2.45mm*0.6mm. It can be used in automotive adaptive headlights, lighting brightness adjustment, display brightness adjustment and other applications.