Vishay Intertechnology Launches Fully Integrated Proximity and Ambient Light Optical Sensor with 16-bit Resolution
For mobile devices such as smart phones, touch phones, PDAs, GPS units, and digital cameras, the new VCNL4020 saves power as a proximity sensor by turning off the display backlight when close to the user, while using its integrated ambient light function for display/keypad adaptive brightness control. Containing all the circuitry needed for these applications in one device, the VCNL4020 eliminates the need for additional light barriers and optical alignment of the IR emitter and photo diode.
While other devices with similar features use chip on printed circuit board technology that results in package heights of 1.2 mm or greater, the VCNL4020 uses a proprietary technology that delivers the lowest height on the market. This gives design engineers greater flexibility in where and how they locate the sensor. For additional flexibility, the VCNL4020 can function at any depth or air gap below the glass window, unlike devices with 8-, 10-, and 12-bit resolutions that require depths or air gaps of 1.5 mm or less. Lower-resolution devices must also be placed away from other components on a costly and dedicated flexible circuit. The 16-bit resolution of the VCNL4020 allows it to be assembled on the main PCB near other components, ensures excellent cross talk immunity, and is especially important given that windows above the sensor absorb typically 90% of the infrared emission.
The VCNL4020’s interrupt function enables the sensor to work independently until a predefined proximity or ambient light event occurs, and then it wakes up the microcontroller. This helps customers reduce their software effort and lower their power consumption by eliminating polling communication traffic between the sensor and microcontroller.
While other products only achieve object detection up to 100 mm, the VCNL4020 provides a programmable LED drive current from 10 mA to 200 mA in 10 mA steps, allowing distances up to 200 mm. To increase the range of the proximity sensor, the VCNL4020 also includes an integrated external emitter driver. Test results with two external emitters have yielded a sensing range of up to 1 meter. The device offers excellent ambient light suppression by modulating the infrared signal. The emitter wavelength peaks at 892 nm and has no visible “red-tail,” unlike many devices from other manufacturers.
The ambient light photo-pin-diode built into the VCNL4020 offers sensitivity close to that of the human eye, with a 16 bit dynamic range for ambient light detection from 0.25 lux to 16 klux. The sensor offers 100 Hz and 120 Hz flicker noise rejection.
Featuring low stand-by current consumption of 1.5 µA, the device offers a supply voltage range of 2.5 V to 3.6 V and I2C bus voltage range from 1.7 V to 5 V. The sensor provides a Moisture Sensitivity Level (MSL) of 4 and operates over a temperature range of - 25 °C to + 85 °C. The VCNL4020 is compliant to RoHS Directive 2011/65/EU and WEEE 2002/96/EC, free of halogens, and compatible with lead (Pb)-free soldering.