APDS-9801

Optical Sensors are devices that can detect the intensity or the presence of ambient light, infrared (IR) radiation, or ultraviolet (UV) radiation in a given environment. The APDS-9801 is an example of an Optical Sensor used for measuring the intensity of ambient light in high ambient light applications such as displays, back lighting, keyboards, and more. This article will discuss the application fields and working principle of the APDS-9801 Optical Sensor.

The APDS-9801 is an optoelectronic device typically used as an ambient light sensor (ALS). It is designed to measure the intensity of visible light, and provides a modulation signal proportional to the incident light. This signal can then be used by the device’s processor to adjust the display back light intensity appropriately.

The APDS-9801 Optical Sensor comprises a dual diode detector and associated circuitry. The diode detectors are sensitive to light in the visible spectrum and have a high accuracy over the color range of a typical LCD display. The two diodes have different gain levels; the green/blue diode has a higher gain than the red/near-IR diode. This allows the sensor to accurately measure the light intensity even if the color temperature of the light is shifted. The sensor’s typical accuracy is around 2%, and the response time is typically 10µs, allowing for very fast regulation of the display back light.

The APDS-9801 is suitable for many different types of installations. It can be used in mobile devices, such as smartphones, and other small devices, as well as large displays. It is also suitable for automotive applications, to measure the light intensity in a vehicle’s cabin. In these applications, the sensor can be used to adjust the display back light intensity according to the changing light conditions.

The APDS-9801’s working principle is based on a simple photovoltaic configuration. The dual diode detector converter absorbs light and generates a photocurrent. This photocurrent is then converted into a voltage signal by an integrated transimpedance amplifier. This voltage signal is then passed through a low-pass filter to allow only the DC component of the signal to pass, which is proportional to the ambient light intensity. The output signal is then sent to the processor for further processing to adjust the display back light.

In conclusion, the APDS-9801 Optical Sensor is an optoelectronic device typically used as an ambient light sensor (ALS). It features dual diode detectors and an integrated transimpedance amplifier, which can accurately measure ambient light in a wide range of applications. The output of the sensor is used by the processor to adjust the display back light intensity appropriately, allowing for a seamless user experience.