TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100A − FEBRUARY 2010
1
The LUMENOLOGY r Company r
r
Copyright E 2010, TAOS Inc.
www.taosinc.com
Features
DAmbient Light Sensing and Proximity
Detection in Single Device
DAmbient 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
DProximity 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
DProgrammable Wait Timer
− Programmable from 2.72 ms
to > 8 Seconds
− Wait State — 65 mA Typical Current
DI2C Interface Compatible
− Up to 400 kHz (I2C Fast Mode)
− Dedicated Interrupt Pin
DSmall 2 mm 2 mm ODFN Package
DSleep Mode — 2.5 mA Typical Current
Applications
DCell Phone Backlight Dimming
DCell Phone Touch Screen Disable
DNotebook/Monitor Security
DAutomatic Speakerphone Enable
DAutomatic 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 TSL2771 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 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.
r
r
Texas Advanced Optoelectronic Solutions Inc.
1001 Klein Road S Suite 300 S Plano, TX 75074 S (972) 673-0759
PACKAGE FN
DUAL FLAT NO-LEAD
(TOP VIEW)
VDD 1
SCL 2
GND 3
6 SDA
5 INT
4 LDR
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100A − FEBRUARY 2010
2
r
r
Copyright E 2010, TAOS Inc. The LUMENOLOGY r Company
www.taosinc.com
Functional Block Diagram
SDA
VDD = 2.4 V
to 3.6 V
INT
SCL
LDR
IR
ADC
ALS Control
IR
Data
Wait Control
Prox
ADC
Prox Control
Prox
Data
IR LED Constant
Current Sink
Clear
ADC
Clear
Data
Prox
Integration
Clear
IR
Upper Limit
Upper Limit
Lower Limit
Lower Limit
Interrupt
I2C Interface
GND
Detailed Description
The TSL2771 light-to-digital device provides on-chip clear and IR diodes, integrating amplifiers, ADCs,
accumulators, clocks, buffers, comparators, a state machine and an I2C interface. Each device combines one
clear photodiode (visible plus infrared) and one infrared-responding (IR) photodiode. Two integrating ADCs
simultaneously convert the amplified photodiode currents into a digital value providing up to 16 bits of resolution.
Upon completion of the conversion cycle, the conversion result is transferred to the clear and IR data registers.
This digital output can be read by a microprocessor through which the illuminance (ambient light level) in Lux
is derived using an empirical formula to approximate the human eye response.
Communication to the device is accomplished through a fast (up to 400 kHz), two-wire I2C serial bus for easy
connection to a microcontroller or embedded controller. The digital output of the TSL2771 device is inherently
more immune to noise when compared to an analog interface.
The TSL2771 provides a separate pin for level-style interrupts. When interrupts are enabled and a pre-set value
is exceeded, the interrupt pin is asserted and remains asserted until cleared by the controlling firmware. The
interrupt feature simplifies and improves system efficiency by eliminating the need to poll a sensor for a light
intensity or proximity value. An interrupt is generated when the value of an ALS or proximity conversion exceeds
either an upper or lower threshold. In addition, a programmable interrupt persistence feature allows the user
to determine how many consecutive exceeded thresholds are necessary to trigger an interrupt. Interrupt
thresholds and persistence settings are configured independently for both ALS and proximity.
Proximity detection requires only a single external IR LED. An internal LED driver can be configured to provide
a constant current sink of 12.5 mA, 25 mA, 50 mA, or 100 mA of current. No external current limiting resistor
is required. The number of proximity LED pulses can be programmed from 1 to 255 pulses. Each pulse has a
16-μs period. This LED current coupled with the programmable number of pulses provides a 2000:1 contiguous
dynamic range.
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100A − FEBRUARY 2010
3
The LUMENOLOGY r Company r
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Terminal Functions
TERMINAL
TYPE
DESCRIPTION
FN PKG NO. NAME TYPE DESCRIPTION
1 VDD Supply voltage.
2 SCL I I2C serial clock input terminal — clock signal for I2C serial data.
3 GND Power supply ground. All voltages are referenced to GND.
4 LDR O LED driver for proximity emitter — up to 100 mA, open drain.
5 INT O Interrupt — open drain.
6 SDA I/O I2C serial data I/O terminal — serial data I/O for I2C .
Available Options
DEVICE PACKAGE − LEADS INTERFACE DESCRIPTION ORDERING NUMBER
TSL27711 FN−6 I2C Vbus = VDD Interface TSL27711FN
TSL27713 FN−6 I2C Vbus = 1.8 V Interface TSL27713FN
Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted)†
Supply voltage, VDD (see Note 1) 3.8 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Digital output voltage range, VO −0.5 V to 3.8 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Digital output current, IO −1 mA to 20 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature range, Tstg −40°C to 85°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ESD tolerance, human body model 2000 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
†Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
NOTE 1: All voltages are with respect to GND.
Recommended Operating Conditions
MIN NOM MAX UNIT
Supply voltage, VDD 2.4 3 3.6 V
Operating free-air temperature, TA−30 70 °C
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100A − FEBRUARY 2010
4
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r
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Operating Characteristics, VDD = 3 V, TA = 25C (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Active — ATIME = 100 ms 175 250
IDD Supply current Wait mode 65 μA
IDD
Supply
current
Sleep mode 2.5 4
μA
V
INT SDA output low voltage
3 mA sink current 00.4
V
VOL INT, SDA output low voltage 6 mA sink current 00.6 V
ILEAK Leakage current, SDA, SCL, INT pins −5 5 μA
ILEAK Leakage current, LDR pin ± 10 μA
V
SCL SDA input high voltage
TSL27711 0.7 VDD
V
VIH SCL, SDA input high voltage TSL27713 1.25 V
V
SCL SDA input low voltage
TSL27711 0.3 VDD
V
VIL SCL, SDA input low voltage TSL27713 0.54 V
ALS Characteristics, VDD = 3 V, TA = 25C, Gain = 16, AEN = 1 (unless otherwise noted)
(Notes 1 ,2, 3)
PARAMETER TEST CONDITIONS CHANNEL MIN TYP MAX UNIT
Dark ALS ADC count value
Ee = 0, AGAIN = 120×,Clear 0 1 5
counts
Dark ALS ADC count value
Ee
=
0
,
AGAIN
=
120×
,
ATIME = 0xDB (100 ms) IR 0 1 5 counts
ALS ADC integration time step size ATIME = 0xFF 2.58 2.72 2.9 ms
ALS ADC Number of integration steps 1 256 steps
Full scale ADC counts per step 1024 steps
Full scale ADC count value ATIME = 0xC0 65535 steps
λp = 625 nm, Ee = 171.6 μW/cm2,
ATIME 0xF6 (27 ms) GAIN 16×
Clear 4000 5000 6000
ALS ADC count value
ATIME = 0xF6 (27 ms), GAIN = 16×
See note 2. IR 790
counts
ALS ADC count value λp = 850 nm, Ee = 219.7 μW/cm2,
ATIME 0xF6 (27 ms) GAIN 16×
Clear 4000 5000 6000
counts
ATIME = 0xF6 (27 ms), GAIN = 16×
See note 3. IR 2800
λ625 nm ATIME 0xF6 (27 ms) See note 2
10 8
15 8
20 8
ALS ADC count value ratio: Clear/IR
λ
p
= 625 nm, ATIME = 0xF6 (27 ms) See note 2. 10.8 15.8 20.8
%
ALS ADC count value ratio: Clear/IR
λ850 nm ATIME 0xF6 (27 ms) See note 3
41
56
68
%
ALS
ADC
count
value
ratio:
Clear/IR
λ
p
= 850 nm, ATIME = 0xF6 (27 ms) See note 3. 41 56 68
%
λ
p
= 625 nm, ATIME = 0xF6 (27 ms) Clear 29.1
R
Irradiance responsivity
λp
=
625
nm
,
ATIME
=
0xF6
(27
ms)
See note 2. IR 4.6 counts/
(μW/
ReIrradiance responsivity λ
p
= 850 nm, ATIME = 0xF6 (27 ms) Clear 22.8 (μW/
c
m2
)
λp
=
850
nm
,
ATIME
=
0xF6
(27
ms)
See note 3. IR 12.7
cm2)
Gi li lti t 1×i
8×−10 10
Gain scalin
g
, relative to 1×
g
ain
16×
10
10
%
Gain
scaling
,
relative
to
1×
gain
setting
16×−10 10 %
se
tti
ng
120×−10 10
%
NOTES: 1. Optical measurements are made using small-angle incident radiation from light-emitting diode optical sources. Visible 625 nm LEDs
and infrared 850 nm LEDs are used for final product testing for compatibility with high-volume production.
2. The 625 nm irradiance Ee is supplied by an AlInGaP light-emitting diode with the following typical characteristics: peak wavelength
λp = 625 nm and spectral halfwidth Δλ½ = 20 nm.
3. The 850 nm irradiance Ee is supplied by a GaAs light-emitting diode with the following typical characteristics: peak wavelength
λp = 850 nm and spectral halfwidth Δλ½ = 42 nm.
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100A − FEBRUARY 2010
5
The LUMENOLOGY r Company r
r
Copyright E 2010, TAOS Inc.
www.taosinc.com
Proximity Characteristics, VDD = 3 V, TA = 25C, Gain = 16, PEN = 1 (unless otherwise noted)
PARAMETER TEST CONDITIONS CONDITION MIN TYP MAX UNIT
IDD Supply current — LDR pulse on 3 mA
ADC conversion time step size PTIME = 0xFF 2.58 2.72 2.9 ms
ALS ADC number of integration steps 1 256 steps
Full scale ADC counts per step 1024 steps
Proximity IR LED pulse count 0 255 pulses
Proximity pulse period Two or more pulses 16 μs
Proximity pulse — LED on time 7.33 μs
PDRIVE=0 75 100 125
Proximity LED Drive
I
INK sink current @ 600 mV, PDRIVE=1 50
mA
Proximity LED Drive
,
LDR pin PDRIVE=2 25 mA
PDRIVE=3 12.5
Proximity distance § 18 inches
§Proximity Distance is dependent upon emitter properties the reflective properties of the proximity reflecting surface. The nominal value shown
uses an IR emitter with a peak wavelength of 850nm and a 20° half angle. The proximity reflecting surface used is a 16” x 20” Kodak 90% grey
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 = 25C, Gain = 16, WEN = 1 (unless otherwise noted)
PARAMETER TEST CONDITIONS CHANNEL MIN TYP MAX UNIT
Wait step size WTIME = 0xFF 2.58 2.72 2.9 ms
Wait number of integration steps 1 256 steps
AC Electrical Characteristics, VDD = 3 V, TA = 25C (unless otherwise noted)
PARAMETER†TEST CONDITIONS MIN TYP MAX UNIT
f(SCL) Clock frequency (I2C only) 0 400 kHz
t(BUF) Bus free time between start and stop condition 1.3 μs
t(HDSTA)
Hold time after (repeated) start condition. After
this period, the first clock is generated. 0.6 μs
t(SUSTA) Repeated start condition setup time 0.6 μs
t(SUSTO) Stop condition setup time 0.6 μs
t(HDDAT) Data hold time 0μs
t(SUDAT) Data setup time 100 ns
t(LOW) SCL clock low period 1.3 μs
t(HIGH) SCL clock high period 0.6 μs
tFClock/data fall time 300 ns
tRClock/data rise time 300 ns
CiInput pin capacitance 10 pF
†Specified by design and characterization; not production tested.
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100A − FEBRUARY 2010
6
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r
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PARAMETER MEASUREMENT INFORMATION
SDA
SCL
StopStart
SCLACK
t(LOWMEXT) t(LOWMEXT)
t(LOWSEXT)
SCLACK
t(LOWMEXT)
Start
Condition
Stop
Condition
P
SDA
t(SUSTO)
t(SUDAT)
t(HDDAT)
t(BUF)
VIH
VIL
SCL
t(SUSTA)
t(HIGH)
t(F)
t(R)
t(HDSTA)
t(LOW)
VIH
VIL
PSS
Figure 1. Timing Diagrams
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100A − FEBRUARY 2010
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TYPICAL CHARACTERISTICS
Figure 2
SPECTRAL RESPONSIVITY
λ − Wavelength − nm
0
400
0.2
0.4
0.6
0.8
1
500 600 700 800 900 1000 1100
Normalized Responsivity
300
Ch 0
Ch 1 25 mA
12.5 mA
Figure 3
VOL − Output Low Voltage − V
12.5
25
37.5
50
62.5
75
87.5
100
112.5
0
Load Current — mA
0 0.3 0.6 0.9 1.2
LDR OUTPUT COMPLIANCE
50 mA
100 mA
Figure 4
NORMALIZED IDD
vs.
VDD and TEMPERATURE
VDD — V
IDD Normalized @ 3 V, 25C
94%
96%
98%
100%
102%
104%
106%
108%
110%
92%
2.7 2.8 2.9 3 3.1 3.2 3.3
75C
50C 25C
0C
Figure 5
NORMALIZED RESPONSIVITY
vs.
ANGULAR DISPLACEMENT
Q − Angular Displacement − °
Normalized Responsivity
0
0.2
0.4
0.6
0.8
1.0
−90 −60 −30 0 30 60 90
Optical Axis
-Q +Q
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100A − FEBRUARY 2010
8
r
r
Copyright E 2010, TAOS Inc. The LUMENOLOGY r Company
www.taosinc.com
PRINCIPLES OF OPERATION
System State Machine
The TSL2771 provides control of ALS, proximity detection, and power management functionality through an
internal state machine (Figure 6). After a power-on-reset, the device is in the sleep mode. As soon as the PON
bit is set, the device will move to the start state. It will then continue through the Prox, Wait, and ALS states. If
these states are enabled, the device will execute each function. If the PON bit is set to 0, the state machine will
continue until all conversions are completed and then go into a low power sleep mode.
Sleep
Start
Wait
ALS
Prox
PON = 1 (r0:b0) PON = 0 (r 0:b0)
Figure 6. Simplified State Diagram
NOTE: In this document, the nomenclature uses the bit field name in italics followed by the register number and
bit number to allow the user to easily identify the register and bit that controls the function. For example, the
power on (PON) is in register 0, bit 0. This is represented as PON (r0:b0).
Clear and IR Diodes
Conventional silicon detectors respond strongly to infrared light, which the human eye does not see. This can
lead to significant error when the infrared content of the ambient light is high (such as with incandescent lighting)
due to the difference between the silicon detector response and the brightness perceived by the human eye.
This problem is overcome in the TSL2771 through the use of two photodiodes. One of the photodiodes, referred
to as the clear channel, is sensitive to both visible and infrared light while the second photodiode is sensitive
primarily to infrared light. Two integrating ADCs convert the photodiode currents to digital outputs. The IRDATA
digital value is used to compensate for the effect of the infrared component of light on the CDATA (clear) digital
value. The ADC digital outputs from the two channels are used in a formula to obtain a value that approximates
the human eye response in units of lux.
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100A − FEBRUARY 2010
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ALS Operation
The ALS engine contains ALS gain control (AGAIN) and two integrating analog-to-digital converters (ADC) for
the clear and IR photodiodes (Figure 7). The ALS integration time (ATIME) impacts both the resolution and the
sensitivity of the ALS reading. Integration of both channels occurs simultaneously and upon completion of the
conversion cycle, the results are transferred to the clear and IR data registers (CDATAx and IR DATAx). This
data is also referred to as channel count. The transfers are double-buffered to ensure that invalid data is not
read during the transfer. After the transfer, the device automatically moves to the next state in accordance with
the configured state machine.
IR
ADC
ALS Control
IR
Data
Clear
ALS
Clear
Data
AGAIN(r 0x0F, b1:0)
1, 8, 16, 120 Gain
Clear
IR
CDATAH(r 0x15), CDATAL(r 0x14)
IRDATAH(r0x17), IRDATAL(r 0x16)
ATIME(r 1)
2.72 ms to 700 ms
Figure 7. ALS Operation
The ALS gain can be set to amplify the clear channel and IR channel by 1, 8, 16, or 120×. The register bits
CONTROL (r0x0F, b1:0) are used to set the gain.
Integration time can be set from 2.7ms to 700ms. The registers for programming the integration and wait times
are a 2’s compliment values. The actual time can be calculated as follows:
ATIME = 256 − Integration Time / 2.72 ms
Inversely, the time can be calculated from the register value as follows:
Integration Time = 2.72 ms × (256 − ATIME)
For example, if a 100-ms integration time is needed, the device needs to be programmed to:
256 − (100 / 2.72) = 256 − 37 = 219 = 0xDB
Conversely, the programmed value of 0xC0 would correspond to:
(256 − 0xC0) × 2.72 = 64 × 2.72 = 172 ms.
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100A − FEBRUARY 2010
10
r
r
Copyright E 2010, TAOS Inc. The LUMENOLOGY r Company
www.taosinc.com
Calculating Lux
The lux calculation is a function of several factors including the clear channel count (CDATA), IR channel count
(IRDATA), ALS gain (AGAIN), and ALS integration time (ATIME). The Clear and IR channel information is
used to calculate an IR Factor (IRF) and IR adjusted count (IAC), which indicates the attenuation to the clear
channel to account for the IR content in the signal. The IR Factor is calculated based on empirical device
measurements under different lighting conditions. Count per lux (CPL) is a function of the AGAIN, ATIME, light
attenuation, and a device factor (DF).
Lux is also dependent upon light attenuation, referred to as glass attenuation (GA). This is used to scale
the lux value to account for some interference such as an aperture, neutral density filter, or a light pipe. If light
is attenuated equally across the spectrum (300 nm to 1100 nm), then a linear GA can be used to compensate
for the light loss of the system. If the sensor is exposed to light without an aperture in an open-air system, then
GA is unity. If the GA is nonlinear, then the IR Factor and LPC will need to be derived under the new conditions.
The lux value can be calculated from the following equation:
lux = IR Adjusted Count (IAC) × Counts per lux (CPL)
Where:
IAC = IRF × CDATA
CPL = Integration Time × Gain / GA × DF
For the TSL2771x FN package in open air to the light source, this factor is 52.
RAW Channel Data
Lux is calculated as a function of the clear count (CDATA) and IR count (IRDATA). Because all registers are
byte-oriented, 16-bit DATA must be created from two register reads:
CDATA = 256 × CDATAH (r0x15) + CDATA (r0x14)
Likewise:
IRDATA = 256 × IRDATAH (r0x17) + IRDATA (r0x16)
Saturation
The device can saturate if the light is brighter than can be accumulated with the light-to-frequency conversion.
The full scale value for saturation will depend upon the integration time programmed into the device. In
saturation, the device accumulates 1024 counts for each 2.72 ms of integration time programmed. For each
ATIME programmed, the maximum count (saturation level) is the lesser of (1024 × (256 − ATIME)) or 65,535.
There is also a second condition that impacts saturation. If there is ripple in the received signal, such as under
fluorescent lights, then the signal will go in and out of saturation and the value read from clear or IR channel
will be less than the maximum but still have some effects of being saturated. Because of this, it is necessary
to lower gain if channel values are above 70% of the saturated calculation. This is especially true in high gain
mode with AC-modulated light sources that produce flicker. Under this condition, a channel reading may be
slightly below the saturated calculation but in reality be saturated during the peaks, resulting in a value less than
the actual light level.
If the ALS integration time is greater than 172 μs, the saturation level is 50,000, otherwise it is calculated as:
SATURATION = 0.75 × (1024 × (256 − ATIME) − 1)
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
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IR Factor and IAC
The IR factor (IRF) is derived from the clear channel (CDATA), which is sensitive to both visible and infrared
light, and the IR channel (IRDATA), which is sensitive primarily to infrared light. The IR Factor is calculated based
on the ratio of the two photodiodes, which provides an optimized equation.
RATIO = IRDATA / CDATA
Because the two photodiodes have different spectral responses, the ratio of the channels will vary depending
on a particular light source’s spectral power distribution (SPD). Light sources such as an incandescent bulb or
sunlight have high amounts of infrared energy, while fluorescent bulbs have virtually no infrared energy.
Fluorescent lights have an IR Factor of approximately 80%; while incandescent light sources, with large
amounts IR, have IR Factors between 10% and 20%.
For RATIO = 0% to 30% IRF = (1.000 − 1.846 × RATIO)
For RATIO = 30% to 38% IRF = (1.268 − 2.740 × RATIO)
For RATIO = 38% to 45% IRF = (0.749 − 1.374 × RATIO)
For RATIO = 45% to 54% IRF = (0.477 − 0.769 × RATIO)
For RATIO > 54% IRF = 0
IRF is used in understanding the light attenuation under different circumstances. However, it is seldom
calculated in the actual implementation. IAC is typically used such that the RATIO not needed in this calculation.
For RATIO = 0% to 30% IAC = (1.000 × CDATA − 1.846 × IRDATA)
For RATIO = 30% to 38% IAC = (1.268 × CDATA − 2.740 × IRDATA)
For RATIO = 38% to 45% IAC = (0.749 × CDATA − 1.374 × IRDATA)
For RATIO = 45% to 54% IAC = (0.477 × CDATA − 0.769 × IRDATA)
For RATIO > 54% IAC = 0
Sample Lux Calculation
Assume:
GA = 1, Gain = 16, Integration Time = 200 ms
Clear Data = 19476, IR Data = 1438 decimal
First, calculate IAC
Ratio = IRDATA / CDATA = 1438 / 19476 = 7.4%
For a ratio of 7.4%, use the first equation:
IAC = (1.000 × CDATA − 1.846 × IRDATA)
IAC = (1.000 × 19476 − 1.846 × 1438)
IAC = 16821
Next, calculate CPL:
CPL = (Integration Time × Gain) / GA × DF
CPL = 200 × 16 / (1 × 52)
CPL = 61.5
Finally, calculate lux:
lux = 16821 / 61.5
lux = 273
Various techniques can be used to eliminate floating point calculations such as multiplying coefficients by 1000
or 1024. Care must be taken to keep the math in the integer size allocated and to keep the appropriate amount
of precision to avoid round-off errors.
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100A − FEBRUARY 2010
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r
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Fluorescent Ripple Rejection
There are many factors that will impact the decision on which value to use for integration time and gain. One
of the first factors is 50/60-Hz ripple rejection for fluorescent lighting. The programmed value needs to be
multiples of 10 / 8.3 ms, or the half cycle time. Both frequencies can be rejected with a programmed value of
50 ms (ATIME=0xED). With this value, the resolution will be 1.3 lux per count. If higher resolution is needed,
a longer integration time may be needed. In this case, the integration time should be programmed in multiples
of 50.
Recommended ALS Operations
With the programming versatility of the integration time and gain, it can be difficult to understand when to use
the different modes. Figure 8 shows a plot of the IRF equations. Figure 9 shows a log-log plot of the lux vs.
integration time and gain with a spectral factor of unity and no IR present.
Figure 8
ATTENUATION
vs.
CH1 /CH0 Ratio
CH1 / CH0 Ratio
I R Factor
Fluorescent
Incandescent
0
0.2
0.4
0.6
0.8
1
0.2 0.4 0.6 0.80
0.1
0.3
0.5
0.7
0.9
Figure 9
Counts
Lux
GAIN AND INTEGRATION TIME
to
LUX (with NO IR)
0.01
0.1
1
10
100
1000
10 k
100 k
1 100 10000
The maximum illuminance that can be measured is approximately 19 k-lux with no IR present. The intercept
with a count of 1 shows the resolution of each setting. The lux values in the table increase as the SF increases
(spectral attenuation increases). For example, if a 10% transmissive glass is used, the lux values would all be
multiplied by 10. The lux values in the table decrease as the IR Factor decreases. For example, with a 10% IR
Factor, which corresponds to a strong incandescent light, the Lux value would need to be divided by 10.
The light level is the next determining factor for configuring device settings. Under bright conditions, the count
will be fairly high. If a low light measurement is needed, a higher gain and/or longer integration time will be
needed. As a general rule, it is recommended to have a clear channel count of at least 10 to accurately apply
the lux equation.
The digital accumulation is limited to 16 bits, which occurs at an integration time of 173 ms. This is the maximum
recommended programmed integration time before increasing the gain. (150 ms is the maximum to reduce the
fluorescent ripple.)
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Proximity Detection
Proximity sensing uses an external light source (generally an infrared emitter) to emit light, which is then viewed
by the integrated light detector to measure the amount of reflected light when an object is in the light path
(Figure 10). The amount of light detected from a reflected surface can then be used to determine an object’s
proximity to the sensor.
IR LED
2771
Surface Reflectivity (SR)
Background Energy (BGE) Optical Crosstalk (OC)
Glass Attenuation (GA)
Distance (D)
Figure 10. Proximity Detection
The TSL2771 has controls for the number of IR pulses (PPCOUNT), the integration time (PTIME), the LED drive
current (PDRIVE), and the photodiode configuration (PDIODE) (Figure 11). The photodiode configuration can
be set to infrared diode (recommended), clear diode, or a combination of both diodes. At the end of the
integration cycle, the results are latched into the proximity data (PDATA) register.
Prox
Integration
Prox Control
Prox
ADC
IR LED Constant
Current Sink
Clear IR
PDATAH(r0x019), PDATAL(r 0x014)
PDRIVE(r 0x0F, b7:6)
Prox
Data
IR
LED
PTIME(r 2)
PPCOUNT(r 0x0E)
VDD
Figure 11. Proximity Detection Operation
The LED drive current is controlled by a regulated current sink on the LDR pin. This feature eliminates the need
to use a current limiting resistor to control LED current. The LED drive current can be configured for 12.5 mA,
25 mA, 50 mA, or 100 mA. For higher LED drive requirements, an external P type transistor can be used to
control the LED current.
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.
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LED On LED Off
16 ms
IR LED Pulses
Subtract
Background
Add IR +
Background
Figure 12. 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 13 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.
Figure 13
PROXIMITY ADC COUNT
vs.
RELATIVE DISTANCE
Proximity ADC Count
Relative Distance
124816
0
200
400
600
800
1000
100 mA,
64 Pulses
100 mA,
16 Pulses
100 mA,
4 Pulses
100 mA,
1 Pulse
25 mA,
1 Pulse
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Interrupts
The interrupt feature of the TSL2771 simplifies and improves system efficiency by eliminating the need to poll
the sensor for a light intensity or proximity value. The interrupt mode is determined by the PIEN or AIEN field
in the ENABLE register.
The TSL2771 implements four 16-bit-wide interrupt threshold registers that allow the user to define thresholds
above and below a desired light level. For ALS, an interrupt can be generated when the ALS clear data (CDATA)
exceeds the upper threshold value (AIHTx) or falls below the lower threshold (AILTx). For proximity, an interrupt
can be generated when the proximity data (PDATA) exceeds the upper threshold value (PIHTx) or falls below
the lower threshold (PILTx).
To further control when an interrupt occurs, the TSL2771 provides an interrupt persistence feature. This feature
allows the user to specify a number of conversion cycles for which an event exceeding the ALS interrupt
threshold must persist (APERS) or the proximity interrupt threshold must persist (PPERS) before actually
generating an interrupt. Refer to the register descriptions for details on the length of the persistence.
IR
ADC
IR
Data
Prox
ADC
Prox
Data
Clear
ADC
Clear
Data
Prox
Integration
Clear
IR
Upper Limit
Upper Limit
Lower Limit
Lower Limit
Prox Persistence
PILTH(r09), PILTL(r 08)
AIHTH(r 07), AIHTL(r 06)
ALS Persistence
AILTH(r 05), AILTL(r 04)
PIHTH(r 0x0B), PIHTL(r 0x0A8) PPERS(r 0x0C, b7:4)
APERS(r 0x0C, b3:0)
Figure 14. Programmable Interrupt
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State Diagram
Figure 15 shows a more detailed flow for the state machine. The device starts in the sleep mode. The PON bit
is written to enable the device. A 2.7-ms delay will occur before entering the start state. If the PEN bit is set, the
state machine will step through the proximity states of proximity accumulate and then proximity ADC
conversion. As soon as the conversion is complete, the state machine will move to the following state.
If the WEN bit is set, the state machine will then cycle through the wait state. If the WLONG bit is set, the wait
cycles are extended by 12× over normal operation. When the wait counter terminates, the state machine will
step to the ALS state.
The AEN should always be set, even in proximity-only operation. In this case, a minimum of 1 integration time
step should be programmed. The ALS state machine will continue until it reaches the terminal count at which
point the data will be latched in the ALS register and the interrupt set, if enabled.
Prox
Check
PON = 1 PON = 0
Sleep
ALS
Check
Wait
Check
Start
Wait
WEN = 1
Prox
Accum
Prox
ADC
ALS
ALS
Delay
PEN = 1
AEN = 1
Up to 255 LED Pulses
Pulse Frequency: 62.5 kHz
Time: 16.3 ms − 4.2 ms
Maximum 4.2ms
Up to 255 steps
Step: 2.72 ms
Time: 2.72 ms − 696 ms
120 Hz Minimum − 8 ms
100 Hz Minimum − 10 ms
Up to 255 steps
Step: 2.72 ms
Time: 2.72 mS − 696 ms
Recommended − 2.72 ms 1024 Counts
WLONG = 0
Counts up to 256 steps
Step: 2.72 ms
Time: 2.72 ms − 696 ms
Minimum − 2.72 ms
WLONG = 1
Counts up to 256 steps
Step: 32.64 ms
Time: 32.64 ms − 8.35 s
Minimum − 32.64 ms
Time: 2.72 ms
Figure 15. Expanded State Diagram
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Power Management
Power consumption can be controlled through the use of the wait state timing because the wait state consumes
only 65 μA of power. Figure 16 shows an example of using the power management feature to achieve an
average power consumption of 155 μA current with four 100-mA pulses of proximity detection and 50 ms of ALS
detection. For I2C read and write transactions, if the PON bit is set to 0 the bit is overridden allowing the oscillator
to be enabled.
4 IR LED Pulses
64 ms (32 ms LED On Time)
2.72 ms
47 ms
50 ms
Prox ADC
Prox Accum
WAIT
ALS
Avg = ((0.032 100) + (2.72 0.175) + (47 0.065) + (50 0.175)) / 100 = 155 mA
State Duration (ms) Current (mA)
Prox Accum (LED On) 0.064 (0.032) 100.0
Prox ADC 2.7 0.175
Wait 47 0.065
ALS 50 0.175
Example: 100 ms Cycle TIme
Figure 16. Power Consumption Calculations
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Basic Software Operation
The following pseudo code shows how to do basic initialization of the TSL2771.
unit8 ATIME,PIME,WTIME,PPCOUNT;
ATIME = 0xff; // 2.72ms − minimum ALS integration time
WTIME = 0xff; // 2.72ms − minimum Wait time
PTIME = 0xff; // 2.72ms − minimum Prox integration time
PPCOUNT = 1; // Minimum prox pulse count
WriteRegData(0, 0); //Disable and Powerdown
WriteRegData (1, ATIME);
WriteRegData (2, PTIME);
WriteRegData (3, WTIME);
WriteRegData (0xe, PPCOUNT);
unit8 PDRIVE, PDIODE, PGAIN, AGAIN;
PDRIVE = 0; //100mA of LED Power
PDIODE = 0x20; // IR Diode
PGAIN = 0; //1x Prox gain
AGAIN = 0; //1x ALS gain
WriteRegData (0xf, PDRIVE | PDIODE | PGAIN | AGAIN);
unit8 WEN, PEN, AEN, PON;
WEN = 8; // Enable Wait
PEN = 4; // Enable Prox
AEN = 2; // Enable ALS
PON = 1; // Enable Power On
WriteRegData (0, WEN | PEN | AEN | PON); // WriteRegData(0,0x0f);
Wait(12); //Wait for 12 ms
int Clear_data, IR_data, Prox_data;
Clear_data = Read_Word(0x14);
IR_data = Read_Word(0x16);
Prox_data = Read_Word(0x18);
WriteRegData (unit8 reg, unit 8 data);
{
m_I2CBus.WriteI2C(0x39, 0x80 | reg 1 &data);
}
unit16 Read_Word (unit8 reg);
{
unit8 barr [2];
m_I2CBus.ReadI2C(0x39, 0xA0 | reg, 2, ref barr);
return (uint16)(barr[0] + 256 barr[1]);
}
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I2C Protocol
Interface and control of the TSL2771 is accomplished through an I2C serial compatible interface (standard or
fast mode) to a set of registers that provide access to device control functions and output data. The device
supports a single slave address of 0x39 hex using 7-bit addressing protocol. (Contact factory for other
addressing options.)
The I2C standard provides for three types of bus transaction: read, write, and a combined protocol (Figure 17).
During a write operation, the first byte written is a command byte followed by data. In a combined protocol, the
first byte written is the command byte followed by reading a series of bytes. If a read command is issued, the
register address from the previous command will be used for data access. Likewise, if the MSB of the command
is not set, the device will write a series of bytes at the address stored in the last valid command with a register
address. The command byte contains either control information or a 5-bit register address. The control
commands can also be used to clear interrupts.
For a complete description of I2C protocols, please review the I2C Specification at:
http://www.semiconductors.philips.com.
AAcknowledge (0)
NNot Acknowledged (1)
PStop Condition
RRead (1)
SStart Condition
SRepeated Start Condition
WWrite (0)
... Continuation of protocol
Master-to-Slave
Slave-to-Master
W
7
Data ByteSlave AddressS
1
AAA
811 1 8
Command Code
1
P
1
...
I2C Write Protocol
I2C Read Protocol
I2C Read Protocol — Combined Format
R
7
DataSlave AddressS
1
AAA
811 1 8
Data
1
P
1
...
W
7
DataSlave AddressS
1
ARA
811 1 8 11
Command Code S
1
A
Data AA
81 8
Data
1
P
1
...
Figure 17. I2C Protocols
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Register Set
The TSL2771 is controlled and monitored by data registers and a command register accessed through the serial
interface. These registers provide for a variety of control functions and can be read to determine results of the
ADC conversions. The register set is summarized in Table 1.
Table 1. Register Address
ADDRESS RESISTER NAME R/W REGISTER FUNCTION RESET VALUE
−− COMMAND W Specifies register address 0x00
0x00 ENABLE R/W Enables states and interrupts 0x00
0x01 ATIME R/W ALS ADC time 0xFF
0x02 PTIME R/W Proximity ADC time 0xFF
0x03 WTIME R/W Wait time 0xFF
0x04 AILTL R/W ALS interrupt low threshold low byte 0x00
0x05 AILTH R/W ALS interrupt low threshold high byte 0x00
0x06 AIHTL R/W ALS interrupt high threshold low byte 0x00
0x07 AIHTH R/W ALS interrupt high threshold high byte 0x00
0x08 PILTL R/W Proximity interrupt low threshold low byte 0x00
0x09 PILTH R/W Proximity interrupt low threshold high byte 0x00
0x0A PIHTL R/W Proximity interrupt high threshold low byte 0x00
0x0B PIHTH R/W Proximity interrupt high threshold high byte 0x00
0x0C PERS R/W Interrupt persistence filters 0x00
0x0D CONFIG R/W Configuration 0x00
0x0E PPCOUNT R/W Proximity pulse count 0x00
0x0F CONTROL R/W Gain control register 0x00
0x12 ID R Device ID ID
0x13 STATUS R Device status 0x00
0x14 CDATA RClear ADC low data register 0x00
0x15 CDATAH RClear ADC high data register 0x00
0x16 IRDATA R IR ADC low data register 0x00
0x17 IRDATAH R IR ADC high data register 0x00
0x18 PDATA R Proximity ADC low data register 0x00
0x19 PDATAH R Proximity ADC high data register 0x00
The mechanics of accessing a specific register depends on the specific protocol used. See the section on I2C
protocols on the previous pages. In general, the COMMAND register is written first to specify the specific
control/status register for following read/write operations.
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Command Register
The command registers specifies the address of the target register for future write and read operations.
Table 2. Command Register
6754
ADD
2310
COMMAND COMMAND TYPE − −
FIELD BITS DESCRIPTION
COMMAND 7 Select Command Register. Must write as 1 when addressing COMMAND register.
TYPE 6:5 Selects type of transaction to follow in subsequent data transfers:
FIELD VALUE INTEGRATION TIME
00 Repeated byte protocol transaction
01 Auto-increment protocol transaction
10 Reserved — Do not use
11 Special function — See description below
Transaction type 00 will repeatedly read the same register with each data access.
Transaction type 01 will provide an auto-increment function to read successive register bytes.
ADD 4:0 Address register/special function register. Depending on the transaction type, see above, this field either
specifies a special function command or selects the specific control-status-register for following write and
read transactions:
FIELD VALUE READ VALUE
00000 Normal — no action
00101 Proximity interrupt clear
00110 ALS interrupt clear
00111 Proximity and ALS interrupt clear
other Reserved — Do not write
ALS/Proximity Interrupt Clear. Clears any pending ALS/Proximity interrupt. This special function is self
clearing.
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Enable Register (0x00)
The ENABLE register is used to power the TSL2571 device on/off, enable functions, and interrupts.
Table 3. Enable Register
6754
PON
2310
ENABLE Reserved Resv AIEN Address
0x00
AENPIEN WEN PEN
FIELD BITS DESCRIPTION
Reserved 7:6 Reserved. Write as 0.
PIEN 5 Proximity interrupt mask. When asserted, permits proximity interrupts to be generated.
AIEN 4 ALS interrupt mask. When asserted, permits ALS interrupts to be generated.
WEN 3 Wait Enable. This bit activates the wait feature. Writing a 1 activates the wait timer. Writing a 0 disables the
wait timer.
PEN 2 Proximity enable. This bit activates the proximity function. Writing a 1 enables proximity. Writing a 0
disables proximity.
AEN 1 ALS Enable. This bit actives the two channel ADC. Writing a 1 activates the ALS. Writing a 0 disables
the ALS.
PON 1, 20Power ON. This bit activates the internal oscillator to permit the timers and ADC channels to operate.
Writing a 1 activates the oscillator. Writing a 0 disables the oscillator.
NOTES: 1. See Power Management section for more information.
2. A minimum interval of 2.72 ms must pass after PON is asserted before either a proximity or ALS can be initiated. This required time
is enforced by the hardware in cases where the firmware does not provide it.
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ALS Timing Register (0x01)
The ALS timing register controls the internal integration time of the ALS clear and IR channel ADCs in 2.72 ms
increments.
Table 4. ALS Timing Register
FIELD BITS DESCRIPTION
ATIME 7:0 VALUE INTEG_CYCLES TIME MAX COUNT
0xFF 1 2.72 ms 1024
0xF6 10 27.2 ms 10240
0xDB 37 100 ms 37888
0xC0 64 174 ms 65535
0x00 256 696 ms 65535
Proximity Time Control Register (0x02)
The proximity timing register controls the integration time of the proximity ADC in 2.72 ms increments. It is
recommended that this register be programmed to a value of 0xFF (1 cycle, 1024 bits).
Table 5. Proximity Time Control Register
FIELD BITS DESCRIPTION
PTIME 7:0 VALUE INTEG_CYCLES TIME MAX COUNT
0xFF 1 2.72 ms 1024
Wait Time Register (0x03)
Wait time is set 2.72 ms increments unless the WLONG bit is asserted in which case the wait times are 12×
longer. WTIME is programmed as a 2’s complement number.
Table 6. Wait Time Register
FIELD BITS DESCRIPTION
WTIME 7:0 REGISTER VALUE WAIT TIME TIME (WLONG = 0) TIME (WLONG = 1)
0xFF 1 2.72 ms 0.032 sec
0xB6 74 200 ms 2.4 sec
0x00 256 700 ms 8.3sec
NOTE: The Proximity Wait Time Register should be configured before PEN and/or AEN is/are asserted.
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ALS Interrupt Threshold Register (0x04 − 0x07)
The ALS interrupt threshold registers provides the values to be used as the high and low trigger points for the
comparison function for interrupt generation. If the value generated by the ALS channel crosses below the low
threshold specified, or above the higher threshold, an interrupt is asserted on the interrupt pin.
Table 7. ALS Interrupt Threshold Register
REGISTER ADDRESS BITS DESCRIPTION
AILTL 0x04 7:0 ALS clear channel low threshold lower byte
AILTH 0x05 7:0 ALS clear channel low threshold upper byte
AIHTL 0x06 7:0 ALS clear channel high threshold lower byte
AIHTH 0x07 7:0 ALS clear channel high threshold upper byte
Proximity Interrupt Threshold Register (0x08 − 0x0B)
The proximity interrupt threshold registers provide the values to be used as the high and low trigger points for
the comparison function for interrupt generation. If the value generated by proximity channel crosses below the
lower threshold specified, or above the higher threshold, an interrupt is signaled to the host processor.
Table 8. Proximity Interrupt Threshold Register
REGISTER ADDRESS BITS DESCRIPTION
PILTL 0x08 7:0 Proximity ADC channel low threshold lower byte
PILTH 0x09 7:0 Proximity ADC channel low threshold upper byte
PIHTL 0x0A 7:0 Proximity ADC channel high threshold lower byte
PIHTH 0x0B 7:0 Proximity ADC channel high threshold upper byte
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Persistence Register (0x0C)
The persistence register controls the filtering interrupt capabilities of the device. Configurable filtering is
provided to allow interrupts to be generated after each ADC integration cycle or if the ADC integration has
produced a result that is outside of the values specified by threshold register for some specified amount of time.
Separate filtering is provided for proximity and ALS functions.
ALS interrupts are generated by looking only at the ADC integration results of CDATA.
Table 9. Persistence Register
6754
APERS
2310
PERS PPERS
Address
0x0C
FIELD BITS DESCRIPTION
PPERS 7:4 Proximity interrupt persistence. Controls rate of proximity interrupt to the host processor.
FIELD VALUE MEANING INTERRUPT PERSISTENCE FUNCTION
0000 −−− Every proximity cycle generates an interrupt
0001 1 1 proximity value out of range
0010 2 2 consecutive proximity values out of range
... ... ...
1111 15 15 consecutive proximity values out of range
APERS 3:0 Interrupt persistence. Controls rate of interrupt to the host processor.
FIELD VALUE MEANING INTERRUPT PERSISTENCE FUNCTION
0000 Every Every ALS cycle generates an interrupt
0001 1 1 clear channel value outside of threshold range
0010 2 2 clear channel consecutive values out of range
0011 3 3 clear channel consecutive values out of range
0100 5 5 clear channel consecutive values out of range
0101 10 10 clear channel consecutive values out of range
0110 15 15 clear channel consecutive values out of range
0111 20 20 clear channel consecutive values out of range
1000 25 25 clear channel consecutive values out of range
1001 30 30 clear channel consecutive values out of range
1010 35 35 clear channel consecutive values out of range
1011 40 40 clear channel consecutive values out of range
1100 45 45 clear channel consecutive values out of range
1101 50 50 clear channel consecutive values out of range
1110 55 55 clear channel consecutive values out of range
1111 60 60 clear channel consecutive values out of range
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Configuration Register (0x0D)
The configuration register sets the wait long time.
Table 10. Configuration Register
67542310
CONFIG Reserved WLONG Address
0x0D
Reserved
FIELD BITS DESCRIPTION
Reserved 7:2 Reserved. Write as 0.
WLONG 1 Wait Long. When asserted, the wait cycles are increased by a factor 12× from that programmed in the
WTIME register.
Reserved 0 Reserved. Write as 0.
Proximity Pulse Count Register (0x0E)
The proximity pulse count register sets the number of proximity pulses that will be transmitted. When proximity
detection is enabled, a proximity detect cycle occurs after each ALS cycle. PPULSE defines the number of
pulses to be transmitted at a 62.5-kHz rate.
NOTE: The ATIME register will be used to time the interval between proximity detection events even if the ALS
function is disabled.
Table 11. Proximity Pulse Count Register
67542310
PPULSE PPULSE Address
0x0E
FIELD BITS DESCRIPTION
PPULSE 7:0 Proximity Pulse Count. Specifies the number of proximity pulses to be generated.
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Control Register (0x0F)
The Control register provides eight bits of miscellaneous control to the analog block. These bits typically control
functions such as gain settings and/or diode selection.
Table 12. Gain Register
67542310
CONTROL PDRIVE Resv Address
0x0F
PDIODE Reserved AGAIN
FIELD BITS DESCRIPTION
PDRIVE 7:6 LED Drive Strength.
FIELD VALUE LED STRENGTH
00 100 mA
01 50 mA
10 25 mA
11 12.5 mA
PDIODE 5:4 Proximity Diode Select.
FIELD VALUE DIODE SELECTION
00 Reserved
01 Proximity uses the clear (broadband) diode
10 Proximity uses the IR diode
11 Proximity uses both the clear diode and the IR 1 diode
Reserved 3:2 Reserved. Write bits as zero (0:0)
AGAIN 1:0 ALS Gain Control.
FIELD VALUE ALS GAIN VALUE
00 1×gain
01 8×gain
10 16×gain
11 120×gain
ID Register (0x12)
The ID Register provides the value for the part number. The ID register is a read-only register.
Table 13. ID Register
67542310
ID ID Address
0x12
FIELD BITS DESCRIPTION
ID
7:0
Part number identification
0x00 = TSL27711
ID 7:0 Part number identification 0x08 = TSL27713
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Status Register (0x13)
The Status Register provides the internal status of the device. This register is read only.
Table 14. Status Register
6754
AVALID
2310
STATUS Reserved Resv AINT Address
0x13
ReservedPINT
FIELD BIT DESCRIPTION
Reserved 7:6 Reserved.
PINT 5 Proximity Interrupt. Indicates that the device is asserting a proximity interrupt.
AINT 4 ALS Interrupt. Indicates that the device is asserting an ALS interrupt.
Reserved 3:1 Reserved.
AVALID 0 ALS Valid. Indicates that the ALS clear / IR channels have completed an integration cycle.
ADC Channel Data Registers (0x14 − 0x17)
ALS clear and IR data are stored as two 16-bit values. To ensure the data is read correctly, a two-byte read I2C
transaction should be used with auto increment protocol bits set in the command register. With this operation,
when the lower byte register is read, the upper eight bits are stored in a shadow register, which is read by a
subsequent read to the upper byte. The upper register will read the correct value even if additional ADC
integration cycles end between the reading of the lower and upper registers.
Table 15. ADC Channel Data Registers
REGISTER ADDRESS BITS DESCRIPTION
CDATAL 0x14 7:0 ALS clear data low byte
CDATAH 0x15 7:0 ALS clear data high byte
IRDATAL 0x16 7:0 ALS IR data low byte
IRDATAH 0x17 7:0 ALS IR data high byte
Proximity Data Register (0x18 − 0x19h)
Proximity data is stored as a 16-bit value. To ensure the data is read correctly, a two-byte read I2C transaction
should be utilized with auto increment protocol bits set in the command register. With this operation, when the
lower byte register is read, the upper eight bits are stored into a shadow register, which is read by a subsequent
read to the upper byte. The upper register will read the correct value even if the next ADC cycle ends between
the reading of the lower and upper registers.
Table 16. PDATA Registers
REGISTER ADDRESS BITS DESCRIPTION
PDATAL 0x18 7:0 Proximity data low byte
PDATAH 0x19 7:0 Proximity data high byte
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APPLICATION INFORMATION: HARDWARE
LED Driver Pin with Proximity Detection
The application hardware circuit with proximity detection requires an LED connected as shown in Figure 18.
Vbat may be an independent power source. If Vbat = Vdd (same source), however, tie the two power lines together
as close to the source as possible.
TSL2771
VBUS VDD
1 mF
RPRP
SCL
SDA
RPI
INT
LDR
LED
1 mF
Vbat
Figure 18. Application Hardware Circuit for Proximity Sensing with Internal LED Driver
If the hardware application requires more than 100 mA of current to drive the LED, then an external transistor
should be used. Note, R2 should be sized adequately to bias the gate voltage given the LDR current mode
setting. See Figure 19.
TSL2771
VBUS VDD
1 mF
RPRP
SCL
SDA
RPI
INT
R1 LDR
LED
R2
1 mF
Vbat
Figure 19. Application Hardware Circuit for Proximity Sensing with External LED Driver Using P-FET
Transistor
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APPLICATION INFORMATION: HARDWARE
PCB Pad Layout
Suggested PCB pad layout guidelines for the Dual Flat No-Lead (FN) surface mount package are shown in
Figure 20.
400
2500
400
1000
1700
650
1000
650
Note: Pads can be
extended further if hand
soldering is needed.
NOTES: A. All linear dimensions are in micrometers.
B. This drawing is subject to change without notice.
Figure 20. Suggested FN Package PCB Layout
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MECHANICAL DATA
PACKAGE FN Dual Flat No-Lead
203 8
6 SDA
5 INT
4 LDR
VDD 1
SCL 2
GND 3
TOP VIEW
SIDE VIEW
BOTTOM VIEW
Lead Free
Pb
300
50
650
2000
75
2000 75
PIN 1
PIN 1
END VIEW
650 50
Seating Plane
PIN OUT
TOP VIEW
Photo-Active Area
750 150
300 50
650
Pin 1 Marker
NOTES: A. All linear dimensions are in micrometers. Dimension tolerance is ± 20 μm unless otherwise noted.
B. The photodiode active area is 466 μm square and its center is 140 μm above and 20 μm to the right of the package center. The die
placement tolerance is ± 75 μm in any direction.
C. Package top surface is molded with an electrically nonconductive clear plastic compound having an index of refraction of 1.55.
D. Contact finish is copper alloy A194 with pre-plated NiPdAu lead finish.
E. This package contains no lead (Pb).
F. This drawing is subject to change without notice.
Figure 21. Package FN — Dual Flat No-Lead Packaging Configuration
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MECHANICAL DATA
TOP VIEW
DETAIL A
2.18 0.05
Ao
0.254
0.02
5 Max
4.00
8.00
3.50 0.05
1.50
4.00
2.00 0.05
+ 0.30
− 0.10
1.75
B
B
AA
1.00
0.25
DETAIL B
2.18 0.05
Bo
5 Max
0.83 0.05
Ko
NOTES: A. All linear dimensions are in millimeters. Dimension tolerance is ± 0.10 mm unless otherwise noted.
B. The dimensions on this drawing are for illustrative purposes only. Dimensions of an actual carrier may vary slightly.
C. Symbols on drawing Ao, Bo, and Ko are defined in ANSI EIA Standard 481−B 2001.
D. Each reel is 178 millimeters in diameter and contains 3500 parts.
E. TAOS packaging tape and reel conform to the requirements of EIA Standard 481−B.
F. In accordance with EIA standard, device pin 1 is located next to the sprocket holes in the tape.
G. This drawing is subject to change without notice.
Figure 22. Package FN Carrier Tape
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MANUFACTURING INFORMATION
The FN package has been tested and has demonstrated an ability to be reflow soldered to a PCB substrate.
The process, equipment, and materials used in these test are detailed below.
The solder reflow profile describes the expected maximum heat exposure of components during the solder
reflow process of product on a PCB. Temperature is measured on top of component. The components should
be limited to a maximum of three passes through this solder reflow profile.
Table 17. TSL2771 Solder Reflow Profile
PARAMETER REFERENCE TSL2771
Average temperature gradient in preheating 2.5°C/sec
Soak time tsoak 2 to 3 minutes
Time above 217°C t1Max 60 sec
Time above 230°C t2Max 50 sec
Time above Tpeak −10°C t3Max 10 sec
Peak temperature in reflow Tpeak 260°C
Temperature gradient in cooling Max −5°C/sec
t3
t2
t1
tsoak
T3
T2
T1
Tpeak
Not to scale — for reference only
Time (sec)
Temperature (C)
Figure 23. TSL2771 Solder Reflow Profile Graph
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MANUFACTURING INFORMATION
Moisture Sensitivity
Optical characteristics of the device can be adversely affected during the soldering process by the release and
vaporization of moisture that has been previously absorbed into the package. To ensure the package contains
the smallest amount of absorbed moisture possible, each device is dry-baked prior to being packed for shipping.
Devices are packed in a sealed aluminized envelope called a moisture barrier bag with silica gel to protect them
from ambient moisture during shipping, handling, and storage before use.
The Moisture Barrier Bags should be stored under the following conditions:
Temperature Range < 40°C
Relative Humidity < 90%
Total Time No longer than 12 months from the date code on the aluminized envelope if
unopened.
Rebaking of the reel will be required if the devices have been stored unopened for more than 12 months and
the Humidity Indicator Card shows the parts to be out of the allowable moisture region.
Opened reels should be used within 168 hours if exposed to the following conditions:
Temperature Range < 30°C
Relative Humidity < 60%
If rebaking is required, it should be done at 50°C for 12 hours.
The FN package has been assigned a moisture sensitivity level of MSL 3.
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PRODUCTION DATA — information in this document is current at publication date. Products conform to
specifications in accordance with the terms of Texas Advanced Optoelectronic Solutions, Inc. standard
warranty. Production processing does not necessarily include testing of all parameters.
LEAD-FREE (Pb-FREE) and GREEN STATEMENT
Pb-Free (RoHS) TAOS’ terms Lead-Free or Pb-Free mean semiconductor products that are compatible with the current
RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous
materials. Where designed to be soldered at high temperatures, TAOS Pb-Free products are suitable for use in specified
lead-free processes.
Green (RoHS & no Sb/Br) TAOS defines Green to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and
Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material).
Important Information and Disclaimer The information provided in this statement represents TAOS’ knowledge and
belief as of the date that it is provided. TAOS bases its knowledge and belief on information provided by third parties,
and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate
information from third parties. TAOS has taken and continues to take reasonable steps to provide representative
and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and
chemicals. TAOS and TAOS suppliers consider certain information to be proprietary, and thus CAS numbers and other
limited information may not be available for release.
NOTICE
Texas Advanced Optoelectronic Solutions, Inc. (TAOS) reserves the right to make changes to the products contained in this
document to improve performance or for any other purpose, or to discontinue them without notice. Customers are advised
to contact TAOS to obtain the latest product information before placing orders or designing TAOS products into systems.
TAOS assumes no responsibility for the use of any products or circuits described in this document or customer product
design, conveys no license, either expressed or implied, under any patent or other right, and makes no representation that
the circuits are free of patent infringement. TAOS further makes no claim as to the suitability of its products for any particular
purpose, nor does TAOS assume any liability arising out of the use of any product or circuit, and specifically disclaims any
and all liability, including without limitation consequential or incidental damages.
TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS, INC. PRODUCTS ARE NOT DESIGNED OR INTENDED FOR
USE IN CRITICAL APPLICATIONS IN WHICH THE FAILURE OR MALFUNCTION OF THE TAOS PRODUCT MAY
RESULT IN PERSONAL INJURY OR DEATH. USE OF TAOS PRODUCTS IN LIFE SUPPORT SYSTEMS IS EXPRESSLY
UNAUTHORIZED AND ANY SUCH USE BY A CUSTOMER IS COMPLETELY AT THE CUSTOMER’S RISK.
LUMENOLOGY, TAOS, the TAOS logo, and Texas Advanced Optoelectronic Solutions are registered trademarks of Texas Advanced
Optoelectronic Solutions Incorporated.
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Copyright E 2010, TAOS Inc. The LUMENOLOGY r Company
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