Working principle and testing of simulated ambient light sensor chip

The ambient light sensor chip can perceive the surrounding light conditions and inform the processing chip to automatically adjust the brightness of the Display backlight to reduce the power consumption of the product. For example, in mobile applications such as mobile phones, notebooks, and tablet computers, the Display consumes up to 30% of the total battery power, and the use of ambient light sensor chips can maximize the working time of the battery. On the other hand, the ambient light sensor chip helps the display provide a soft picture. When the ambient brightness is high, the LCD display using the ambient light sensor chip will automatically adjust to high brightness. When the external environment is dark, the display will be adjusted to low brightness.

The ambient light sensor chip has the characteristics of low dark current, low illuminance response, high sensitivity, and linear change of current with increased illuminance; built-in dual sensitive elements, automatic attenuation of near infrared, and spectral response close to the human eye function curve (black: human eye response Curve, blue: photoresistor response curve, green: ambient light response curve); another consideration when choosing an appropriate light sensor chip is to choose a sensor with an ideal spectral response. Ordinary PIN photodiodes or photoresistors (passive or active) themselves have a very wide spectral response range, including IR rays and even UV rays. In theory, users need to choose a light sensor chip that can only sense visible light (380~770nm) and weaken useless IR and UV signals. Some sensor chips also have built-in micro-signal CMOS amplifiers, high-precision voltage sources and corrections. The circuit has large output current, wide operating voltage range, and good temperature stability; optional optical nano-material packaging, visible light transmission, ultraviolet cutoff, near-infrared relative attenuation, enhanced optical filtering effect; compliance with EU RoHS directive, lead-free, no Cadmium, the photoresistor on the market does not meet the above standards.

The editor here recommends an ambient light sensor chip from Taiwan Wanghong, which is represented by Gongcai.com. This is an analog ambient light sensor chip. The ambient light sensor chip-ALS-AK510 is a low-cost The visible light sensor has a current output proportional to the ambient light level. It has a built-in optical filter to provide a response or “photosensitive” close to the human eye. Connect the output current in series with a resistor and it can be converted into voltage. The dynamic range is determined by the external resistance and power supply (10K and 5V give a range of 0 to 160 Lux, but a 1K resistance can exceed 700 Lux). The internal dark current elimination circuit can maintain stable accuracy over the full temperature range, even at low light levels.

Features of ambient light sensor chip-ALS-AK510:

Photosensitivity close to the human eye

High infrared suppression with built-in optical filter

Highly linear current output and ambient light level

Stable temperature

Corresponding relationship integration of photocurrent amplifier

Excellent dark current performance

High humidity immunity

The Links:   KCG057QV1DB-G77 NL128102BC28-07

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