New from Vishay is a fully integrated proximity and ambient light optical sensor with a low height of 0,8 mm. The VCNL4020 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 4,8 x 2,3 x 0,8 mm 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 smartphones, touchphones, PDAs, GPS units and digital cameras, the device 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 IC eliminates the need for additional light barriers and optical alignment of the IR emitter and photodiode.
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 crosstalk immunity, and is especially important given that windows above the sensor absorb typically 90% of the infrared emission. The device’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.
The VCNL4020 provides a programmable LED drive current from 10 mA to 200 mA in 10 mA steps, allowing object detection at distances up to 200 mm. To increase the range of the proximity sensor, the IC also includes an integrated external emitter driver. Test results with two external emitters have yielded a sensing range of up to 1 m.
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’. 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 standby 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.
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