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PDF TSL2771 Data sheet ( Hoja de datos )
| Número de pieza | TSL2771 | |
| Descripción | LIGHT-TO-DIGITAL CONVERTER | |
| Fabricantes | TAOS | |
| Logotipo |  |
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Features
D Ambient Light Sensing and Proximity
Detection in a Single Device
D Ambient Light Sensing (ALS)
− Approximates Human Eye Response
− Programmable Analog Gain
− Programmable Integration Time
− Programmable Interrupt Function with
Upper and Lower Threshold
− Resolution Up to 16 Bits
− Very High Sensitivity — Operates Well
Behind Darkened Glass
− Up to 1,000,000:1 Dynamic Range
D Proximity Detection
− Programmable Number of IR Pulses
− Programmable Current Sink for the IR
LED — No Limiting Resistor Needed
− Programmable Interrupt Function with
Upper and Lower Threshold
− Covers a 2000:1 Dynamic Range
D Programmable Wait Timer
− Programmable from 2.72 ms
to > 8 Seconds
− Wait State — 65 mA Typical Current
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
PACKAGE FN
DUAL FLAT NO-LEAD
(TOP VIEW)
VDD 1
SCL 2
6 SDA
5 INT
GND 3
4 LDR
Package Image Not Actual Size
D I2C Interface Compatible
− Up to 400 kHz (I2C Fast Mode)
− Dedicated Interrupt Pin
D Small 2 mm y 2 mm ODFN Package
D Sleep Mode — 2.5 mA Typical Current
Applications
D Cell Phone Backlight Dimming
D Cell Phone Touch Screen Disable
D Notebook/Monitor Security
D Automatic Speakerphone Enable
D Automatic Menu Popup
Description
The TSL2771 family of devices provides both ambient light sensing (ALS) and proximity detection (when
coupled with an external IR LED). The ALS approximates human eye response to light intensity under a variety
of lighting conditions and through a variety of attenuation materials. The proximity detection feature allows a
large dynamic range of operation for use in short distance detection behind dark glass such as in a cell phone
or for longer distance measurements for applications such as presence detection for monitors or laptops. The
programmable proximity detection enables continuous measurements across the entire range. In addition, an
internal state machine provides the ability to put the device into a low power mode in between ALS and proximity
measurements providing very low average power consumption.
While useful for general purpose light sensing, the device is particularly useful for display management with the
purpose of extending battery life and providing optimum viewing in diverse lighting conditions. Display panel
and keyboard backlighting can account for up to 30 to 40 percent of total platform power. The ALS features are
ideal for use in tablets, notebook PCs, LCD monitors, flat-panel televisions, and cell phones.
The proximity function is targeted specifically towards cell phone, LCD monitor, laptop, and flat-panel television
applications. In cell phones, the proximity detection can detect when the user positions the phone close to their
ear. The device is fast enough to provide proximity information at a high repetition rate needed when answering
a phone call. It can also detect both close and far distances so the application can implement more complex
algorithms to provide a more robust interface. In laptop or monitor applications, the product is sensitive enough
to determine whether a user is in front of the laptop using the keyboard or away from the desk. This provides
both improved green power saving capability and the added security to lock the computer when the user is not
present.
The LUMENOLOGY r Company
r
Texas Advanced Optoelectronic Solutions Inc.
1001 Klein Road S Suite 300 S Plano, TX 75074 S (972r) 673-0759
www.taosinc.com
Copyright E 2011, TAOS Inc.
1
1 page  
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
Proximity Characteristics, VDD = 3 V, TA = 255C, PEN = 1 (unless otherwise noted)
PARAMETER
TEST CONDITIONS
CONDITION
MIN TYP MAX UNIT
IDD Supply current
ADC conversion time step size
LDR pulse on
PTIME = 0xFF
3
2.58 2.72
mA
2.9 ms
ADC number of integration steps
1 256 steps
ADC counts per step
PTIME = 0xFF
0 1023 counts
IR LED pulse count
0 255 pulses
pulse period
Two or more pulses
16 μs
LED pulse width — LED on time
7.3 μs
PDRIVE=0
75 100
125
LED drive current
ISINK sink current @ 600 mV,
LDR pin
PDRIVE=1
PDRIVE=2
50
mA
25
PDRIVE=3
12.5
Operating distance (See note 1)
18 inches
NOTE 1: Proximity Operating Distance is dependent upon emitter properties and the reflective properties of the proximity surface. The nominal
value shown uses an IR emitter with a peak wavelength of 850nm and a 20° half angle. The proximity surface used is a 90% reflective
(white surface) 16 × 20-inch Kodak Gray Card. 60 mw/SR, 100 mA, 64 pulses, open view (no glass). Note: Greater distances are
achievable with appropriate system considerations.
Wait Characteristics, VDD = 3 V, TA = 255C, WEN = 1 (unless otherwise noted)
PARAMETER
TEST CONDITIONS
CHANNEL
MIN TYP
Wait step size
WTIME = 0xFF
2.58 2.72
Wait number of integration steps
1
MAX
2.9
256
UNIT
ms
steps
AC Electrical Characteristics, VDD = 3 V, TA = 255C (unless otherwise noted)
PARAMETER†
TEST CONDITIONS
MIN
f(SCL)
Clock frequency (I2C only)
0
t(BUF)
Bus free time between start and stop condition
1.3
t(HDSTA)
Hold time after (repeated) start condition. After
this period, the first clock is generated.
0.6
t(SUSTA)
Repeated start condition setup time
t(SUSTO)
Stop condition setup time
t(HDDAT)
Data hold time
t(SUDAT)
Data setup time
t(LOW)
SCL clock low period
t(HIGH)
SCL clock high period
tF Clock/data fall time
tR Clock/data rise time
Ci Input pin capacitance
† Specified by design and characterization; not production tested.
0.6
0.6
0
100
1.3
0.6
TYP MAX UNIT
400 kHz
μs
μs
μs
μs
μs
ns
μs
μs
300 ns
300 ns
10 pF
The LUMENOLOGY r Company
r
www.taosinc.com
r
Copyright E 2011, TAOS Inc.
5
5 Page 
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
The number of LED pulses can be programmed to any value between 1 and 255 pulses as needed. Increasing
the number of LED pulses at a given current will increase the sensor sensitivity. Sensitivity grows by the square
root of the number of pulses. Each pulse has a 16-μs period.
Add IR + Subtract
Background Background
LED On
LED Off
16 ms
IR LED Pulses
Figure 10. Proximity IR LED Waveform
The proximity integration time (PTIME) is the period of time that the internal ADC converts the analog signal
to a digital count. It is recommend that this be set to a minimum of PTIME = 0xFF or 2.72 ms.
The combination of LED power and number of pulses can be used to control the distance at which the sensor
can detect proximity. Figure 11 shows an example of the distances covered with settings such that each curve
covers 2× the distance. Counts up to 64 pulses provide a 16× range.
1000
800
PROXIMITY ADC COUNT
vs.
RELATIVE DISTANCE
25 mA,
1 Pulse
100 mA,
16 Pulses
100 mA,
64 Pulses
600
400
100 mA,
4 Pulses
100 mA,
200 1 Pulse
0
1y 2y 4y
8y
16y
Relative Distance
Figure 11
The LUMENOLOGY r Company
r
www.taosinc.com
r
Copyright E 2011, TAOS Inc.
11
11 Page | ||
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| PDF Descargar | [ Datasheet TSL2771.PDF ] | |
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