ISL29147_15 Datasheet, PDF (1/15 Pages) Intersil Corporation – Low Power Ambient Light and Proximity Sensor with Enhanced Infrared Rejection

DATASHEET
Low Power Ambient Light and Proximity Sensor with
Enhanced Infrared Rejection
ISL29147
The ISL29147 is a low power Ambient Light Sensor (ALS) and
proximity (PROX) sensor. It has a built-in IR-LED for the
proximity function. The ALS function measures the amount of
light (in the visible spectrum) incident on the ISL29147.
The ALS function has a programmable ambient IR-rejection,
which allows fine tuning of light source variations and is ideal
for light sensor applications under dark protective glass. The
ALS provides a 12-bit measurement. A passive optical filter
removes unwanted wavelengths (IR or Ultraviolet) to ensure
accurate ALS measurement.
The proximity function includes a new offset adjustment to
compensate for the IR light reflected off the inside of the
protective glass cover and back to the ISL29147 sensor. This
offset adjustment allows the sensor to compensate for these
internal reflections and preserve the dynamic range of the
proximity measurement.
The built-in current-driver pulses an external infrared LED at a
programmed current for 90µs. The infrared light that is
reflected and received by the ISL29147 is digitized by an 8-bit
ADC. The proximity sensor also has a passive optical filter
designed to pass IR and reject visible wavelengths.
The ISL29147 provides a hardware pin to indicate an interrupt
event. The interrupt pin saves power as the host microcontroller
can ‘wake-up’ on an interrupt event and does not need to poll
the device for an interrupt event. The interrupt generator is
user configurable and provides several options for ALS and
PROX trigger configurations. The ISL29147 supports an SMBus
compatible I²C interface for configuration and control.
Features
• Internal IR-LED and sensor for a complete solution
• Ideal for applications under dark or tinted glass
• Enhanced ambient sunlight rejection to 40k Lux
• Programmable proximity sleep time between proximity
measurements optimizes power consumption
• Hardware interrupt - no polling required
• Programmable IR compensation to fine-tune ALS
performance for various glass compositions
• Programmable IR LED drive current to 250mA
• Operates from 2.25V to 3.63V V_DD
• Power-down I_DD, typical 0.2µA_DC
• Tiny 2.40x4x1.2 (mm) optical co-package
Applications
• Display dimming and adjustment
- Mobile devices: smart phones, PDA, GPS
- Computing: monitors, laptops, notebooks
- Picture frames, tablet-PCs, LCD-TV
• Object detection
- Touchscreen disabling
- Smart power-saving
V_DD
R₁
C₂
100Ω 1µF
C₁
1µF
VDD_PULLUP
SCL, SDA and
INT PULLUPs
5
6
7
8
U1
VDD
SCL
GND
LED+
SDA
INT
IRDR
LED-
4
3
2
1
ISL29147
250
SMBus MASTER
200
SCL
SDA
INT
150
100
50
IRDR 250mA
IRDR 125mA
R₁: 100Ω 5% RESISTOR
C₁, C₂: 1µF CERAMIC 10V CAPACITOR
FIGURE 1. TYPICAL APPLICATIONS CIRCUIT
0
0
50
100
150
DISTANCE (mm)
FIGURE 2. PROXIMITY SENSITIVITY
January 6, 2015
1
FN8409.3
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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