Ambient 7 Click is a light intensity-sensing and measuring Click board™, which features an accurate light-intensity sensor labeled as SFH 5701 A01, made by Osram Opto Semiconductors. It offers a high measurement accuracy in wide range of the actual light intensity. The spectral response of the sensor is calibrated to closely match the spectral response of the human eye. Thanks to its high level of integration, the sensor requires a minimal number of external components.
Ambient 7 Click is supported by a mikroSDK compliant library, which includes functions that simplify software development.
The influence of the light source type on the measurement accuracy is quite reduced. The sensor is capable of converting the light intensity from any type of light source, including daylight, fluorescent light, LED light, incandescent light, and so on. It also features Integrated dark current suppression and thermal compensation, which helps eliminating enviromental effects to measurement results. Its low power consumption, compact size, and high sensitivity, make this sensor an ideal solution for both the IoT light-sensing applications, but also for portable or handheld devices which utilize an accurate light intensity sensing, such as the TFT/LCD screens, keypad backlight, Smart TVs, cell phones, digital cameras, and similar.
As mentioned previously, Ambient 7 Click uses the SFH 5701 A01, an accurate light-intensity sensor from Osram Opto Semiconductors. This sensor has many features that make it a perfect solution for small designs such as the Ambient 7 Click board™. One of these features is certainly its high level of integration, that allows a minimal number of external components, leaving room for an additional operational amplifier, labeled as OPA344, made by Texas Instruments, proven in many designs.
As the SFH 5701 A01 limits the output current proportionaly to ambient light intensity, it creates an analog voltage on the R2 resistor (shunt). That voltage is directly proportional to the flowing current and thus the ambient light intensity. The previously mentioned operational amplifier serves as a unity gain amplifier (buffer), to ensure good analog measurement signal integrity. The output of the unity gain amplifier is routed to the mikroBUS™ AN pin. The voltage on the AN pin can be measured bz internal ADC integrated in the main MCU on the development board.
The accuracy of SFH 5701 A01 sensor is not influenced by the light source type. It is calibrated so its spectral response is closely matched to a spectral response of the human eye. It is also worth to mention that the sensor qualification test plan is referenced to the guidelines of AEC-Q102 – a failure mechanism based stress test qualification for discrete optoelectronic semiconductors in automotive applications.
Built in thermal compensation ensures that the measurement results are valid in wide temperature range and thanks to integrated dark current suppression, the output signal while the sensor is exposed to dark environment is as minimal as possible. The sensor is operational in very wide Illuminance range – from 0.01lx up to 10000lx. In other words, it has linear response over 6 decades of illumination range.
This Click board™ is designed to be operated only with 5V logic level. A proper logic voltage level conversion should be performed before the Click board™ is used with MCUs with logic levels of 3.3V.
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