ISL29021 Digital Proximity Sensor

The ISL29021 is an integrated proximity and infrared sensor with a built-in IR LED driver and I²C Interface (SMBus Compatible). This device provides infrared sensing to allow proximity estimation featured with interrupt function.

For infrared and proximity sensing, an internal ADC has been designed based on the charge-balancing A/D conversion technique.

The ADC is used to digitize the output signal from the photodiode array when the internal IR LED driver is turned on and off for the programmed time periods under user-selected modulation frequency to drive the external IR LED. As this proximity sensor employs a noise cancellation scheme to highly reject unwanted IR noise, the digital output of proximity sensing decreases with distance. The driver output current is user selectable up to 100mA to drive different types of IR emitters LEDs.

Four different modes of operation can be selected via the I²C interface: programmable IR sensing once, programmable proximity sensing once, programmable continuous IR sensing and programmable continuous proximity sensing. The programmable one-time operation modes greatly reduce power because an immediate automatic shutdown reduces overall supply current less than 0.5