Novel Chipscale Sensor Detects Both Proximity and Ambient Light
Promising to extend the battery lifetime and reduce circuit complexity and component count in advanced portable devices, the CM3612 from Capella Microsystems combines proximity and ambient light sensor functions in a single chip. The proximity detector in the chip is topped with a microscopic 830- to 880-nm IR filter and the ambient light sensor diode has a filter that passes only the green light band (450 to 650 nm) to better match the brightness sensing mechanism of the human eye. The 2.35 x 1.8 x 1-mm OPLGA package also contains a digital low-pass filter to remove florescent light flicker, a 12-bit A/D converter, a DSP, a temperature compensation circuit, an I²C interface, an oscillator, and a driver for an IR emitter. The sensor accepts from 2.6 to 3.7 volts with a typical current consumption of130 µA. The CM3612 version provides the ambient light value via a 12-bit I2C interface and the CM3601 version uses a DAC to output the ambient light value as an analog output signal. From $1.20 each in 10,000-unit quantities.