New Technologies and Energy Harvesting
Vishay – Low-profile fully-integrated proximity / ambient light sensor with 16-bit resolution (VCNL4020)Jun 19 2012 - New Technologies and Energy Harvesting [More New Technologies and Energy Harvesting Articles]
A new fully-integrated proximity and ambient light optical sensor, offering the industry’s lowest height of just 0.8mm, the VCNL4020 has been introduced by Vishay.
The device combines an IR emitter, a photo-pin-diode for proximity, an ambient light detector, a signal processing IC, and a 16-bit ADC in one small 4.8mm x 2.3mm x 0.8mm rectangular leadless (LLP) package.
The 3-in-1 sensor features an interrupt function, supports I²C bus communication interface, and greatly simplifies window and sensor placement in a wide variety of consumer and industrial applications.
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 PCB 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 1.5mm 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 typically achieve object detection up to only 100mm, the VCNL4020 provides a programmable LED drive current from 10mA to 200mA in 10mA steps, allowing distances up to 200mm. 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 1m. The device offers excellent ambient light suppression by modulating the infrared signal. The emitter wavelength peaks at 892nm and has no visible ‘red-tail’, unlike traditional devices.
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 0.25lux to 16klux. The sensor offers 100Hz and 120Hz flicker noise rejection.
Featuring low standby current consumption of 1.5µA, the device offers a supply voltage range of 2.5V to 3.6V and I²C bus voltage range from 1.7V to 5V. The sensor provides a Moisture Sensitivity Level (MSL) of 4 and operates over a temperature range of -25C to +85C. 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.
Samples and production quantities of the new VCNL4020 are available now. The VCNL4020 demo kit enabling quick and easy evaluation of the sensor in designers’ applications is also available, says the company.More news from Vishay