OPT4001 measures the ambient light that illuminates the device. This device measures light with a spectral response very closely matched to the human eye, and with excellent infrared rejection.

Matching the sensor spectral response to that of the human eye response is vital because ambient light sensors are used to measure and help create excellent human lighting experiences. Strong rejection of infrared light, which a human does not see, is a crucial component of this matching. This matching makes the OPT4001 especially good for operation underneath windows that are visibly dark, but infrared transmissive.

OPT4001 is fully self-contained to measure the ambient light and report the result in ADC codes directly proportional to lux digitally over the I²C bus. The result can also be used to alert a system and interrupt a processor with the INT pin (with SOT-5X3 package variant). The result can also be summarized with a programmable threshold comparison and communicated with the INT pin(with SOT-5X3 package variant).

OPT4001 is by default configured to operate in automatic full-scale range detection mode that always selects the best full-scale range setting for the given lighting conditions. There are 9 full-scale range settings, one of which can be selected manually as well. Setting the device to operate in automatic full-scale range detection mode frees the user from having to program their software for potential iterative cycles of measurement and readjustment of the full-scale range until good for any given measurement. With device exhibiting excellent linearity over the entire 28 bit dynamic range of measurement no additional linearity calibration is required at system level.

OPT4001 can be configured to operate in continuous or one-shot measurement modes. The device offers 12 conversion times ranging from 600 μs to 800 ms. The device starts up in a low-power shutdown state, such that the OPT4001 only consumes active-operation power after being programmed into an active state.

OPT4001 optical filtering system is not excessively sensitive to small particles and micro-shadows on the optical surface. This reduced sensitivity is a result of the relatively minor device dependency on uniform density optical illumination of the sensor area for infrared rejection. Proper optical surface cleanliness is always recommended for best results on all optical devices.