PROXIMITY/AMBIENT LIGHT SENSOR - Silicon Laboratories
Description
Si1120
PROXIMITY/AMBIENT LIGHT SENSOR WITH PWM OUTPUT
Features
Typically 50 cm meter proximity High EMI immunity without
range with single pulse
shielded packaging
Seven precision optical
Power supply: 2.
2–3.
7 V
measurement modes:
Operating temperature range:
3 proximity ranges
–40 to +85 °C
3 dc ambient ranges
Typical 10 µA current
1 calibration mode
consumption
Low-noise ambient cancelling Programmable 400/50 mA LED
circuit allows maximum
constant current driver output
sensitivity with 8–12 bit resolution Allows independent LED supply
ALS works in direct sunlight
voltage
(100 klux)
Small outline 3 x 3 mm (ODFN)
Minimum reflectance sensitivity
<1 µW/cm2
Applications
Handsets Touchless switches Occupancy sensors Consumer electronics
Notebooks/PCs Industrial automation Display backlighting control Photo-interrupter
Pin Assignments
PRX TXGD
TXO STX
Si1120
ODFN
18 27 36 45
VSS MD SC VDD
U.
S.
Patent #5,864,591 U.
S.
Patent #6,198,118 Other patents pending
Description
The Si1120 is a low-power, reflectance-based proximity and ambient light sensor with advanced analog signal processing and analog PWM output.
It includes an integrated differential photodiode, signal processor, and LED driver.
Proximity sensing is based on the measurement of reflected light from an external, optically-isolated, strobed LED.
A separate visible light photodiode is used for ambient light sensing.
The standard package for the Si1120 is an 8-pin ODFN.
Rev.
1.
0 8/10
Copyright © 2010 by Silicon Laboratories
Si1120
Si1120
Functional Block Diagram
Transparent window
Product Case
Infrared emitter
Optical Block
IR VIS
STX SC MD
Ambient Light Sources
Transparent window
MUX
AMP
CMP
BUF
PRX
RAMP GEN
VREG
VDD
MODE CTRL
TXO TX
VSS
TXGD
PWM Output
3.
3 V
C1 1.
0 uF
VDD / DC+
P0.
0/VREF
GND / DC-
P0.
1 / AGND P0.
2 / XTAL1 P0.
3 / XTAL2
P0.
4 / TX
P0.
5 / RX P0.
6 / CNVSTR
P0.
7 / IREF0
DCEN VBAT
GND
C8051F931
...
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