TSL2771

TAOS Inc.
is now
ams AG
The technical content of this TAOS datasheet is still valid.
Contact information:
Headquarters:
ams AG
Tobelbaderstrasse 30
8141 Unterpremstaetten, Austria
Tel: +43 (0) 3136 500 0
e-Mail: [email protected]
Please visit our website at www.ams.com
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
r
r
TAOS100B − FEBRUARY 2011
Features
PACKAGE FN
DUAL FLAT NO-LEAD
(TOP VIEW)
D Ambient Light Sensing and Proximity
Detection in a Single Device
−
−
−
−
D Proximity Detection
Description
6 SDA
SCL 2
5 INT
GND 3
4 LDR
Package Image Not Actual Size
D I2C Interface Compatible
D
D
− Up to 400 kHz (I2C Fast Mode)
− Dedicated Interrupt Pin
Small 2 mm 2 mm ODFN Package
Sleep Mode — 2.5 mA Typical Current
am
lc s
on A
te G
nt
st
il
D
− 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
Programmable Wait Timer
− Programmable from 2.72 ms
to > 8 Seconds
− Wait State — 65 mA Typical Current
VDD 1
lv
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
al
id
D Ambient Light Sensing (ALS)
Applications
D
D
D
D
D
Cell Phone Backlight Dimming
Cell Phone Touch Screen Disable
Notebook/Monitor Security
Automatic Speakerphone Enable
Automatic Menu Popup
ca
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.
ni
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.
Te
ch
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
Copyright E 2011, TAOS Inc.
r
Texas Advanced Optoelectronic Solutions Inc.
1001 Klein Road S Suite 300 S Plano, TX 75074 S (972)
r 673-0759
www.taosinc.com
1
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
Functional Block Diagram
Interrupt
IR LED Constant
Current Sink
Prox Control
GND
Prox
Integration
Prox
ADC
INT
Upper Limit
Prox
Data
Lower Limit
VDD
SCL
I2C Interface
Wait Control
Upper Limit
CH0
Data
ALS Control
CH0
SDA
CH1
Data
am
lc s
on A
te G
nt
st
il
CH1
ADC
Lower Limit
lv
CH0
ADC
al
id
LDR
CH1
Detailed Description
The TSL2771 light-to-digital device provides on-chip photodiodes, integrating amplifiers, ADCs, accumulators,
clocks, buffers, comparators, a state machine, and an I2C interface. Each device combines a Channel 0
photodiode (CH0), which is responsive to both visible and infrared light, and a channel 1 photodiode (CH1),
which is responsive primarily to infrared light. 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 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 device is inherently more
immune to noise when compared to an analog interface.
ni
ca
The device 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.
Te
ch
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.
Copyright E 2011, TAOS Inc.
The LUMENOLOGY r Company
r
r
2
www.taosinc.com
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
Terminal Functions
TERMINAL
TYPE
DESCRIPTION
NAME
NO.
GND
3
INT
5
O
Interrupt — open drain (active low).
LDR
4
O
LED driver for proximity emitter — up to 100 mA, open drain.
SCL
2
I
I2C serial clock input terminal — clock signal for I2C serial data.
SDA
6
I/O
VDD
1
Power supply ground. All voltages are referenced to GND.
al
id
I2C serial data I/O terminal — serial data I/O for I2C .
Supply voltage.
DEVICE
ADDRESS
INTERFACE DESCRIPTION
ORDERING NUMBER
TSL27711
0x39
FN−6
I2C
TSL27713
0x39
FN−6
I2C Vbus = 1.8 V Interface
TSL27715†
0x29
FN−6
I2C Vbus = VDD Interface
TSL27715FN
FN−6
I2C
TSL27717FN
Vbus = VDD Interface
TSL27711FN
TSL27713FN
am
lc s
on A
te G
nt
st
il
TSL27717†
†
PACKAGE − LEADS
lv
Available Options
0x29
Vbus = 1.8 V Interface
Contact TAOS for availability.
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.
ca
NOTE 1: All voltages are with respect to GND.
Recommended Operating Conditions
ni
Supply voltage, VDD
NOM
MAX
2.6
3
3.6
V
70
°C
−30
UNIT
Te
ch
Operating free-air temperature, TA
MIN
The LUMENOLOGY r Company
Copyright E 2011, TAOS Inc.
r
r
www.taosinc.com
3
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
Operating Characteristics, VDD = 3 V, TA = 25C (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
Active — LDR pulses off
Supply current
VOL
INT SDA output low voltage
INT,
I LEAK
Leakage current, SDA, SCL, INT pins
I LEAK
Leakage current, LDR pin
VIH
SCL SDA input high voltage
SCL,
VIL
SCL SDA input low voltage
SCL,
MAX
175
250
Wait mode
65
Sleep mode — no I2C activity
2.5
μA
4
3 mA sink current
0
0.4
6 mA sink current
0
0.6
−5
5
± 10
TSL27711, TSL27715
0.7 VDD
TSL27713, TSL27717
1.25
V
μA
μA
V
0.3 VDD
TSL27711, TSL27715
0.54
V
lv
TSL27713, TSL27717
UNIT
al
id
IDD
TYP
PARAMETER
Dark ADC count value
am
lc s
on A
te G
nt
st
il
ALS Characteristics, VDD = 3 V, TA = 25C, Gain = 16, AEN = 1 (unless otherwise noted)
(Notes 1 ,2, 3)
TEST CONDITIONS
Ee = 0, AGAIN = 120×,
ATIME = 0xDB (100 ms)
ADC integration time step size
CHANNEL
MIN
TYP
MAX
CH0
0
1
5
CH1
0
1
5
2.58
2.72
ATIME = 0xFF
ADC Number of integration steps
ADC counts per step
ADC count value
1
Irradiance responsivity
1024
counts
0
65535
counts
μW/cm2,
λp = 850 nm, Ee = 219.7
ATIME = 0xF6 (27 ms) See note 3.
CH0
4000
5000
4000
5000
CH1
CH0
6000
790
CH1
6000
2800
λp = 625 nm
nm, ATIME = 0xF6 (27 ms) See note 2
2.
10 8
10.8
15 8
15.8
20.8
20 8
λp = 850 nm
nm, ATIME = 0xF6 (27 ms) See note 3
3.
41
56
68
λp = 625 nm, ATIME = 0xF6 (27 ms)
See note 2.
CH0
29.1
CH1
4.6
λp = 850 nm, ATIME = 0xF6 (27 ms)
See note 3.
CH0
22.8
CH1
%
counts/
(μW/
cm2)
12.7
8×
−10
10
16×
−10
10
10
−10
10
120×
counts
%
ni
G i scaling,
Gain
li
relative
l ti to
t 1× gain
i
setting
ms
steps
0
ca
Re
2.9
256
ATIME = 0xC0
λp = 625 nm, Ee = 171.6
ATIME = 0xF6 (27 ms) See note 2.
ADC count value ratio: CH1/CH0
counts
ATIME = 0xFF
μW/cm2,
ADC count value
UNIT
Te
ch
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.
Copyright E 2011, TAOS Inc.
The LUMENOLOGY r Company
r
r
4
www.taosinc.com
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
Proximity Characteristics, VDD = 3 V, TA = 25C, PEN = 1 (unless otherwise noted)
IDD
TEST CONDITIONS
Supply current
LDR pulse on
ADC conversion time step size
PTIME = 0xFF
CONDITION
PTIME = 0xFF
IR LED pulse count
pulse period
TYP
2.58
2.72
mA
ms
1
256
steps
0
1023
counts
0
255
pulses
μs
16
LED pulse width — LED on time
μs
7.3
PDRIVE=0
75
PDRIVE=1
Operating distance (See note 1)
125
50
PDRIVE=2
PDRIVE=3
100
mA
25
12.5
lv
ISINK sink current @ 600 mV,
LDR pin
UNIT
2.9
Two or more pulses
LED drive current
MAX
3
ADC number of integration steps
ADC counts per step
MIN
al
id
PARAMETER
18
inches
am
lc s
on A
te G
nt
st
il
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 = 25C, WEN = 1 (unless otherwise noted)
PARAMETER
Wait step size
TEST CONDITIONS
CHANNEL
WTIME = 0xFF
Wait number of integration steps
MIN
TYP
MAX
2.58
2.72
2.9
ms
256
steps
1
UNIT
AC Electrical Characteristics, VDD = 3 V, TA = 25C (unless otherwise noted)
PARAMETER†
MIN
TYP
MAX
UNIT
400
kHz
Clock frequency (I2C only)
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
0
μs
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
tF
Clock/data fall time
Ci
ni
ca
0
300
ch
tR
Clock/data rise time
Input pin capacitance
ns
300
ns
10
pF
Specified by design and characterization; not production tested.
Te
†
TEST CONDITIONS
f(SCL)
The LUMENOLOGY r Company
Copyright E 2011, TAOS Inc.
r
r
www.taosinc.com
5
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
PARAMETER MEASUREMENT INFORMATION
t(LOW)
t(R)
t(F)
VIH
SCL
VIL
t(BUF)
t(HIGH)
t(HDDAT)
t(SUSTA)
t(SUSTO)
t(SUDAT)
al
id
VIH
SDA
VIL
P
S
Stop
Condition
S
Start
Condition
Start
P
Stop
t(LOWSEXT)
SCLACK
SCLACK
t(LOWMEXT)
t(LOWMEXT)
t(LOWMEXT)
am
lc s
on A
te G
nt
st
il
SCL
lv
t(HDSTA)
SDA
Te
ch
ni
ca
Figure 1. Timing Diagrams
Copyright E 2011, TAOS Inc.
The LUMENOLOGY r Company
r
r
6
www.taosinc.com
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
TYPICAL CHARACTERISTICS
TYPICAL LDR CURRENT
vs.
VOLTAGE
SPECTRAL RESPONSIVITY
160
1
Ch 0
140
al
id
100 mA
0.6
0.4
Ch 1
0.2
100
80
50 mA
lv
LDR Current — mA
120
60
40
am
lc s
on A
te G
nt
st
il
Normalized Responsivity
0.8
25 mA
20
12.5 mA
0
300
0
400
500
600
700
800
900 1000 1100
0
0.5
1
λ − Wavelength − nm
Figure 2
108%
2
2.5
3
Figure 3
NORMALIZED RESPONSIVITY
vs.
ANGULAR DISPLACEMENT
NORMALIZED IDD
vs.
VDD and TEMPERATURE
110%
1.5
LDR Voltage − V
1.0
25C
ca
50C
102%
100%
96%
ni
0C
98%
Optical Axis
104%
Normalized Responsivity
0.8
106%
ch
IDD Normalized @ 3 V, 25C
75C
0.6
0.4
0.2
94%
2.8
Te
92%
2.7
2.9
3
3.1
3.2
3.3
VDD — V
0
−90
-Q
Figure 4
The LUMENOLOGY r Company
+Q
−60
−30
0
30
60
Q − Angular Displacement − °
90
Figure 5
Copyright E 2011, TAOS Inc.
r
r
www.taosinc.com
7
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
PRINCIPLES OF OPERATION
System State Machine
al
id
The device 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
PON = 1 (r 0:b0)
PON = 0 (r 0:b0)
Prox
lv
Start
am
lc s
on A
te G
nt
st
il
ALS
Wait
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).
Photodiodes
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.
Te
ch
ni
ca
This problem is overcome through the use of two photodiodes. The Channel 0 photodiode, referred to as the
CH0 channel, is sensitive to both visible and infrared light, while the Channel 1 photodiode, referred to as CH1,
is sensitive primarily to infrared light. Two integrating ADCs convert the photodiode currents to digital outputs.
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.
Copyright E 2011, TAOS Inc.
The LUMENOLOGY r Company
r
r
8
www.taosinc.com
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
ALS Operation
ATIME(r 1)
2.72 ms to 696 ms
CH0
ALS
CH0
Data
C0DATAH(r 0x15), C0DATA(r 0x14)
ALS Control
CH1
Data
C1DATAH(r 0x17), C1DATA(r 0x16)
am
lc s
on A
te G
nt
st
il
CH1
ADC
lv
CH0
al
id
The ALS engine contains ALS gain control (AGAIN) and two integrating analog-to-digital converters (ADC) for
the Channel 0 and Channel 1 photodiodes. 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 data registers (C0DATA and C1DATA). This data is also
referred to as channel count. The transfers are double-buffered to ensure data integrity.
CH1
AGAIN(r 0x0F, b1:0)
1, 8, 16, 120 Gain
Figure 7. ALS Operation
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)
In order to reject 50/60-Hz ripple strongly present in fluorescent lighting, the integration time needs to
be programmed in 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) or multiples of 50 ms (i.e. 100, 150, 200, 400, 600).
The registers for programming the AGAIN hold a two-bit value representing a gain of 1×, 8×, 16×, or 120×. The
gain, in terms of amount of gain, will be represented by the value AGAINx, i.e. AGAINx = 1, 8, 16, or 120.
ca
Lux Equation
ch
ni
The lux calculation is a function of CH0 channel count (C0DATA), CH1 channel count (C1DATA), ALS gain
(AGAINx), and ALS integration time in milliseconds (ATIME_ms). If an aperture, glass/plastic, or a light pipe
attenuates the light equally across the spectrum (300 nm to 1100 nm), then a scaling factor referred to as glass
attenuation (GA) can be used to compensate for attenuation. For a device in open air with no aperture or
glass/plastic above the device, GA = 1. If it is not spectrally flat, then a custom lux equation with new coefficients
should be generated. (See TAOS application note).
Te
Counts per Lux (CPL) needs to be calculated only when ATIME or AGAIN is changed, otherwise it remains a
constant. The first segment of the equation (Lux1) covers fluorescent and incandescent light. The second
segment (Lux2) covers dimmed incandescent light. The final lux is the maximum of Lux1, Lux2, or 0.
CPL = (ATIME_ms × AGAINx) / (GA × 53)
Lux1 = (C0DATA − 2 × C1DATA) / CPL
Lux2 = (0.6 × C0DATA − C1DATA) / CPL
Lux = MAX(Lux1, Lux2, 0)
The LUMENOLOGY r Company
Copyright E 2011, TAOS Inc.
r
r
www.taosinc.com
9
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
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 8). The amount of light detected from a reflected surface can then be used to determine an object’s
proximity to the sensor.
Distance (D)
IR LED
Prox
Sensor
Optical Crosstalk (OC)
am
lc s
on A
te G
nt
st
il
Background Energy (BGE)
al
id
Glass Attenuation (GA)
lv
Surface Reflectivity (SR)
Figure 8. Proximity Detection
The device has controls for the number of IR pulses (PPCOUNT), the integration time (PTIME), the LED drive
current (PDRIVE), and the photodiode configuration (PDIODE) (Figure 9). The photodiode configuration can
be set to CH1 diode (recommended), CH0 diode, or a combination of both diodes. At the end of the integration
cycle, the results are latched into the proximity data (PDATA) register.
IR
LED
VDD
PDRIVE(r 0x0F, b7:6)
PTIME(r 2)
IR LED Constant
Current Sink
Prox Control
Prox
Integration
CH1
Prox
Data
PDATAH(r 0x019), PDATAL(r 0x018)
PPCOUNT(r 0x0E)
ca
CH0
Prox
ADC
Figure 9. Proximity Detection Operation
Te
ch
ni
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.
Copyright E 2011, TAOS Inc.
The LUMENOLOGY r Company
r
r
10
www.taosinc.com
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 +
Background
Subtract
Background
LED Off
16 ms
IR LED Pulses
lv
Figure 10. Proximity IR LED Waveform
al
id
LED On
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.
am
lc s
on A
te G
nt
st
il
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.
PROXIMITY ADC COUNT
vs.
RELATIVE DISTANCE
1000
25 mA,
1 Pulse
100 mA,
16 Pulses
600
400
100 mA,
1 Pulse
ni
200
100 mA,
4 Pulses
ca
Proximity ADC Count
800
100 mA,
64 Pulses
0
8
16
Relative Distance
ch
1 2 4
Te
Figure 11
The LUMENOLOGY r Company
Copyright E 2011, TAOS Inc.
r
r
www.taosinc.com
11
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
Interrupts
The interrupt feature simplifies and improves system efficiency by eliminating the need to poll the sensor for
light intensity or proximity values outside of a user-defined range. While the interrupt function is always enabled
and it’s status is available in the status register (0x13), the output of the interrupt state can be enabled using
the proximity interrupt enable (PIEN) or ALS interrupt enable (AIEN) fields in the enable register (0x00).
al
id
Four 16-bit interrupt threshold registers allow the user to set limits below and above a desired light level and
proximity range. An interrupt can be generated when the ALS CH0 data (C0DATA) falls outside of the desired
light level range, as determined by the values in the ALS interrupt low threshold registers (AILTx) and ALS
interrupt high threshold registers (AIHTx). Likewise, an out-of-range proximity interrupt can be generated when
the proximity data (PDATA) falls below the proximity interrupt low threshold (PILTx) or exceeds the proximity
interrupt high threshold (PIHTx). It is important to note that the low threshold value must be less than the high
threshold value for proper operation.
am
lc s
on A
te G
nt
st
il
lv
To further control when an interrupt occurs, the device provides a persistence filter. The persistence filter allows
the user to specify the number of consecutive out-of-range ALS or proximity occurrences before an interrupt
is generated. The persistence register (0x0C) allows the user to set the ALS persistence (APERS) and the
proximity persistence (PPERS) values. See the persistence register for details on the persistence filter values.
Once the persistence filter generates an interrupt, it will continue until a special function interrupt clear command
is received (see command register).
Prox
Integration
Prox
ADC
PIHTH(r 0x0B), PIHTL(r 0x0A)
PPERS(r 0x0C, b7:4)
Upper Limit
Prox Persistence
Prox
Data
Lower Limit
PILTH(r 09), PILTL(r 08)
AIHTH(r 07), AIHTL(r 06)
CH1
Upper Limit
CH0
ADC
APERS(r 0x0C, b3:0)
ALS Persistence
CH0
Data
CH0
ca
Lower Limit
AILTH(r 05), AILTL(r 04)
Te
ch
ni
Figure 12. Programmable Interrupt
Copyright E 2011, TAOS Inc.
The LUMENOLOGY r Company
r
r
12
www.taosinc.com
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
State Diagram
Figure 13 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 2.72-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.
al
id
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.
lv
Up to 256 steps
Step: 2.72 ms
Time: 2.72 ms − 696 ms
120 Hz Minimum − 8 ms
100 Hz Minimum − 10 ms
Sleep
2.72 ms
PON = 1
Prox
Delay
PON = 0
am
lc s
on A
te G
nt
st
il
Up to 255 LED Pulses
Pulse Frequency: 62.5 kHz
Time: 16 ms − 4.2 ms
Maximum 4.2ms
Start
Prox
Accum
ALS
PEN = 1
Prox
Check
ALS
Check
Prox
ADC
ALS
Delay
AEN = 1
Counts up to 256 steps
Step: 2.72 ms
Time: 2.72 mS − 696 ms
Recommended − 2.72 ms 1024 Counts
Wait
Check
Time: 2.72 ms
WEN = 1
Wait
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
Te
ch
ni
ca
Figure 13. Expanded State Diagram
The LUMENOLOGY r Company
Copyright E 2011, TAOS Inc.
r
r
www.taosinc.com
13
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
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 14 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.
Prox ADC
64 ms (32 ms LED On Time)
2.72 ms
Example: 100 ms Cycle TIme
WAIT
47 ms
Duration (ms)
Current (mA)
am
lc s
on A
te G
nt
st
il
State
lv
Prox Accum
al
id
4 IR LED Pulses
ALS
Prox Accum (LED On)
Prox ADC
Wait
ALS
50 ms
0.064 (0.032)
2.7
47
50
100.0
0.175
0.065
0.175
Avg = ((0.032 100) + (2.72 0.175) + (47 0.065) + (50 0.175)) / 100 = 155 mA
Te
ch
ni
ca
Figure 14. Power Consumption Calculations
Copyright E 2011, TAOS Inc.
The LUMENOLOGY r Company
r
r
14
www.taosinc.com
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
I2C Protocol
Interface and control are 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 devices support the 7-bit
I2C addressing protocol.
al
id
The I2C standard provides for three types of bus transaction: read, write, and a combined protocol (Figure 15).
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.
...
Acknowledge (0)
Not Acknowledged (1)
Stop Condition
Read (1)
Start Condition
Repeated Start Condition
Write (0)
Continuation of protocol
Master-to-Slave
Slave-to-Master
1
S
am
lc s
on A
te G
nt
st
il
A
N
P
R
S
S
W
lv
The I2C bus protocol was developed by Philips (now NXP). For a complete description of the I2C protocol, please
review the NXP I2C design specification at http://www.i2c−bus.org/references/.
7
1
Slave Address
W
1
A
8
1
Command Code
8
A
1
Data Byte
A
8
1
1
...
P
I2C Write Protocol
1
S
7
1
Slave Address
R
1
A
8
1
Data
A
Data
A
1
...
P
I2C Read Protocol
1
1
8
1
1
7
1
1
Slave Address
W
A
Command Code
A
S
Slave Address
R
A
8
Data
1
8
A
Data
1
A
1
...
P
I2C Read Protocol — Combined Format
Figure 15. I2C Protocols
Te
ch
ni
S
7
ca
1
The LUMENOLOGY r Company
Copyright E 2011, TAOS Inc.
r
r
www.taosinc.com
15
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
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
−−
COMMAND
W
0x00
ENABLE
R/W
Enables states and interrupts
0x01
ATIME
R/W
ALS ADC time
0x02
PTIME
R/W
Proximity ADC time
0x03
WTIME
R/W
Wait time
0x04
AILTL
R/W
ALS interrupt low threshold low byte
0x05
AILTH
R/W
ALS interrupt low threshold high byte
0x06
AIHTL
R/W
ALS interrupt high threshold low byte
0x07
AIHTH
R/W
ALS interrupt high threshold high byte
0x08
PILTL
R/W
Proximity interrupt low threshold low byte
0x00
R/W
Proximity interrupt low threshold high byte
0x00
R/W
Proximity interrupt high threshold low byte
0x00
R/W
Proximity interrupt high threshold high byte
0x00
R/W
Interrupt persistence filters
0x00
R/W
Configuration
0x00
PILTH
PIHTL
RESET VALUE
al
id
0x00
0x00
0xFF
0xFF
0xFF
lv
0x00
0x00
0x00
am
lc s
on A
te G
nt
st
il
0x09
0x0A
REGISTER FUNCTION
Specifies register address
0x00
0x0B
PIHTH
0x0C
PERS
0x0D
CONFIG
0x0E
PPCOUNT
R/W
Proximity pulse count
0x00
0x0F
CONTROL
R/W
Control register
0x00
0x12
ID
R
Device ID
0x13
STATUS
R
Device status
0x00
0x14
C0DATA
R
CH0 ADC low data register
0x00
0x15
C0DATAH
R
CH0 ADC high data register
0x00
0x16
C1DATA
R
CH1 ADC low data register
0x00
0x17
C1DATAH
R
CH1 ADC high data register
0x00
R
Proximity ADC low data register
0x00
R
Proximity ADC high data register
0x00
PDATA
0x19
PDATAH
ca
0x18
ID
Te
ch
ni
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.
Copyright E 2011, TAOS Inc.
The LUMENOLOGY r Company
r
r
16
www.taosinc.com
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
Command Register
The command registers specifies the address of the target register for future write and read operations.
Table 2. Command Register
6
COMMAND
COMMAND
FIELD
BITS
COMMAND
7
TYPE
6:5
5
4
3
TYPE
2
1
0
−−
ADD
DESCRIPTION
al
id
7
Select Command Register. Must write as 1 when addressing COMMAND register.
Selects type of transaction to follow in subsequent data transfers:
DESCRIPTION
00
Repeated byte protocol transaction
01
Auto-increment protocol transaction
10
Reserved — Do not use
11
Special function — See description below
am
lc s
on A
te G
nt
st
il
lv
FIELD VALUE
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 field. Depending on the transaction type, see above, this field either
specifies a special function command or selects the specific control-status-register for the following write
and read transactions. The field values listed below apply only to special function commands:
FIELD VALUE
DESCRIPTION
00000
Normal — no action
00101
Proximity interrupt clear
00110
ALS interrupt clear
00111
Proximity and ALS interrupt clear
other
Reserved — Do not write
Te
ch
ni
ca
ALS/Proximity Interrupt Clear clears any pending ALS/Proximity interrupt. This special function is self
clearing.
The LUMENOLOGY r Company
Copyright E 2011, TAOS Inc.
r
r
www.taosinc.com
17
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
Enable Register (0x00)
The ENABLE register is used to power the device on/off, enable functions, and interrupts.
Table 3. Enable Register
6
Reserved
ENABLE
5
4
3
2
1
0
PIEN
Resv
AIEN
WEN
PEN
AEN
PON
DESCRIPTION
Address
0x00
al
id
7
FIELD
BITS
Reserved
7:6
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, 2
0
Power 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.
am
lc s
on A
te G
nt
st
il
lv
Reserved. Write as 0.
Te
ch
ni
ca
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.
Copyright E 2011, TAOS Inc.
The LUMENOLOGY r Company
r
r
18
www.taosinc.com
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
ALS Timing Register (0x01)
The ALS timing register controls the internal integration time of the ALS channel ADCs in 2.72 ms increments.
Table 4. ALS Timing Register
7:0
DESCRIPTION
VALUE
INTEG_CYCLES
TIME
MAX COUNT
0xFF
1
2.72 ms
1024
0xF6
10
27.2 ms
0xDB
37
101 ms
0xC0
64
174 ms
0x00
256
696 ms
al
id
BITS
10240
37888
65535
65535
lv
FIELD
ATIME
Proximity Time Control Register (0x02)
am
lc s
on A
te G
nt
st
il
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 integration cycle).
Table 5. Proximity Time Control Register
FIELD
BITS
PTIME
7:0
DESCRIPTION
VALUE
INTEG_CYCLES
TIME
MAX COUNT
0xFF
1
2.72 ms
1023
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
WTIME
7:0
DESCRIPTION
REGISTER VALUE
WAIT TIME
TIME (WLONG = 0)
TIME (WLONG = 1)
0xFF
1
2.72 ms
0.032 sec
74
201 ms
2.4 sec
256
696 ms
8.3 sec
ca
0xB6
0x00
Te
ch
ni
NOTE: The Proximity Wait Time Register should be configured before PEN and/or AEN is/are asserted.
The LUMENOLOGY r Company
Copyright E 2011, TAOS Inc.
r
r
www.taosinc.com
19
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
ALS Interrupt Threshold Registers (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 C0DATA 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
BITS
0x04
7:0
ALS low threshold lower byte
DESCRIPTION
AILTH
0x05
7:0
ALS low threshold upper byte
AIHTL
0x06
7:0
ALS high threshold lower byte
AIHTH
0x07
7:0
ALS high threshold upper byte
al
id
ADDRESS
AILTL
lv
REGISTER
Proximity Interrupt Threshold Registers (0x08 − 0x0B)
am
lc s
on A
te G
nt
st
il
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
ADDRESS
PILTL
0x08
PILTH
0x09
PIHTL
0x0A
PIHTH
0x0B
BITS
DESCRIPTION
7:0
Proximity low threshold lower byte
7:0
Proximity low threshold upper byte
7:0
Proximity high threshold lower byte
7:0
Proximity high threshold upper byte
Te
ch
ni
ca
REGISTER
Copyright E 2011, TAOS Inc.
The LUMENOLOGY r Company
r
r
20
www.taosinc.com
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
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 using C0DATA.
Table 9. Persistence Register
6
PERS
5
4
3
PPERS
FIELD
BITS
PPERS
7:4
0
Address
0x0C
DESCRIPTION
FIELD VALUE
MEANING
0000
−−−
0001
1
lv
Proximity interrupt persistence. Controls rate of proximity interrupt to the host processor.
INTERRUPT PERSISTENCE FUNCTION
Every proximity cycle generates an interrupt
1 proximity value out of range
am
lc s
on A
te G
nt
st
il
3:0
1
APERS
0010
2
2 consecutive proximity values out of range
...
...
...
1111
15
15 consecutive proximity values out of range
Interrupt persistence. Controls rate of interrupt to the host processor.
FIELD VALUE
MEANING
0000
Every
0001
1
1 value outside of threshold range
0010
2
2 consecutive values out of range
INTERRUPT PERSISTENCE FUNCTION
Every ALS cycle generates an interrupt
0011
3
3 consecutive values out of range
0100
5
5 consecutive values out of range
0101
10
10 consecutive values out of range
0110
15
15 consecutive values out of range
0111
20
20 consecutive values out of range
1000
25
25 consecutive values out of range
1001
30
30 consecutive values out of range
1010
35
35 consecutive values out of range
1011
40
40 consecutive values out of range
1100
45
45 consecutive values out of range
1101
50
50 consecutive values out of range
1110
55
55 consecutive values out of range
1111
60
60 consecutive values out of range
Te
ch
ni
ca
APERS
2
al
id
7
The LUMENOLOGY r Company
Copyright E 2011, TAOS Inc.
r
r
www.taosinc.com
21
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
Configuration Register (0x0D)
The configuration register sets the wait long time.
Table 10. Configuration Register
7
6
5
CONFIG
4
3
2
0
WLONG
Reserved
Address
0x0D
al
id
Reserved
1
FIELD
BITS
Reserved
7:2
DESCRIPTION
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.
lv
Reserved. Write as 0.
am
lc s
on A
te G
nt
st
il
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
7
PPULSE
6
5
4
3
2
1
0
Address
0x0E
PPULSE
BITS
7:0
DESCRIPTION
Proximity Pulse Count. Specifies the number of proximity pulses to be generated.
Te
ch
ni
ca
FIELD
PPULSE
Copyright E 2011, TAOS Inc.
The LUMENOLOGY r Company
r
r
22
www.taosinc.com
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
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. Control Register
6
CONTROL
5
FIELD
BITS
7:6
3
ResvPDIODE
PDRIVE
PDRIVE
4
2
DESCRIPTION
LED Drive Strength.
100 mA
01
50 mA
10
25 mA
11
12.5 mA
3:2
AGAIN
1:0
Proximity Diode Select.
DIODE SELECTION
00
Reserved
01
Proximity uses the CH0 diode
10
Proximity uses the CH1 diode
11
Proximity uses both diodes
Reserved.
Write bits as zero (0:0)
ALS Gain Control.
FIELD VALUE
ID Register (0x12)
Address
0x0F
lv
LED STRENGTH
00
FIELD VALUE
Reserved
AGAIN
am
lc s
on A
te G
nt
st
il
5:4
0
Reserved
FIELD VALUE
PDIODE
1
al
id
7
ALS GAIN VALUE
00
1× gain
01
8× gain
10
16× gain
11
120× gain
6
Table 13. ID Register
5
ni
7
ca
The ID Register provides the value for the part number. The ID register is a read-only register.
3
BITS
ID
7:0
1
0
Address
0x12
DESCRIPTION
0x00 = TSL27711 & TSL27715
Part number identification
0x09 = TSL27713 & TSL27717
Te
FIELD
2
ID
ch
ID
4
The LUMENOLOGY r Company
Copyright E 2011, TAOS Inc.
r
r
www.taosinc.com
23
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
Status Register (0x13)
The Status Register provides the internal status of the device. This register is read only.
Table 14. Status Register
STATUS
6
Reserved
5
4
PINT
Resv
AINT
3
2
1
0
Reserved
AVALID
FIELD
BIT
Reserved
7:6
DESCRIPTION
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
AVALID
0
Reserved.
lv
Reserved.
Address
0x13
al
id
7
ALS Valid. Indicates that the ALS channels have completed an integration cycle.
am
lc s
on A
te G
nt
st
il
ADC Channel Data Registers (0x14 − 0x17)
ALS data is 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
C0DATA
0x14
7:0
ALS CH0 data low byte
C0DATAH
0x15
7:0
ALS CH0 data high byte
C1DATA
0x16
7:0
ALS CH1 data low byte
C1DATAH
0x17
7:0
ALS CH1 data high byte
Proximity Data Registers (0x18 − 0x19)
ch
ni
ca
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
ADDRESS
BITS
DESCRIPTION
PDATAL
0x18
7:0
Proximity data low byte
PDATAH
0x19
7:0
Proximity data high byte
Te
REGISTER
Copyright E 2011, TAOS Inc.
The LUMENOLOGY r Company
r
r
24
www.taosinc.com
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
APPLICATION INFORMATION: HARDWARE
LED Driver Pin with Proximity Detection
In a proximity sensing system, the IR LED can be pulsed by the TSL2771 with more than 100 mA of rapidly
switching current, therefore, a few design considerations must be kept in mind to get the best performance. The
key goal is to reduce the power supply noise coupled back into the device during the LED pulses.
al
id
The first recommendation is to use two power supplies; one for the device VDD and the other for the IR LED.
In many systems, there is a quiet analog supply and a noisy digital supply. By connecting the quiet supply to
the VDD pin and the noisy supply to the LED, the key goal can be meet. Place a 1-μF low-ESR decoupling
capacitor as close as possible to the VDD pin and another at the LED anode, and a 22-μF capacitor at the output
of the LED voltage regulator to supply the 100-mA current surge.
Voltage
Regulator
VDD
1 mF
RP
RP
am
lc s
on A
te G
nt
st
il
C*
GND
Voltage
Regulator
lv
VBUS
TSL2771
RPI
INT
SCL
LDR
22 mF
1 mF
SDA
IR LED
* Cap Value Per Regulator Manufacturer Recommendation
Figure 16. Proximity Sensing Using Separate Power Supplies
If it is not possible to provide two separate power supplies, the device can be operated from a single supply.
A 22-Ω resistor in series with the VDD supply line and a 1-μF low ESR capacitor effectively filter any power supply
noise. The previous capacitor placement considerations apply.
VBUS
Voltage
Regulator
22 W
VDD
1 mF
22 mF
RP
ca
GND
ch
ni
1 mF
TSL2771
RP
RPI
INT
SCL
LDR
SDA
IR LED
Figure 17. Proximity Sensing Using Single Power Supply
Te
VBUS in the above figures refers to the I2C bus voltage which is either VDD or 1.8 V. Be sure to apply the specified
I2C bus voltage shown in the Available Options table for the specific device being used.
The I2C signals and the Interrupt are open-drain outputs and require pull−up resistors. The pull-up resistor (RP)
value is a function of the I2C bus speed, the I2C bus voltage, and the capacitive load. The TAOS EVM running
at 400 kbps, uses 1.5-kΩ resistors. A 10-kΩ pull-up resistor (RPI) can be used for the interrupt line.
The LUMENOLOGY r Company
Copyright E 2011, TAOS Inc.
r
r
www.taosinc.com
25
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
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 18.
1000
al
id
2500
Note: Pads can be
extended further if hand
soldering is needed.
1000
400
lv
650
1700
am
lc s
on A
te G
nt
st
il
650
400
NOTES: A. All linear dimensions are in micrometers.
B. This drawing is subject to change without notice.
Te
ch
ni
ca
Figure 18. Suggested FN Package PCB Layout
Copyright E 2011, TAOS Inc.
The LUMENOLOGY r Company
r
r
26
www.taosinc.com
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
MECHANICAL DATA
PACKAGE FN
Dual Flat No-Lead
TOP VIEW
466 10
PIN OUT
TOP VIEW
PIN 1
2000 100
6 SDA
al
id
VDD 1
466
10
SCL 2
5 INT
am
lc s
on A
te G
nt
st
il
2000
100
END VIEW
4 LDR
lv
GND 3
Photodiode Array Area
SIDE VIEW
295
Nominal
650 50
203 8
650
BOTTOM VIEW
CL of Photodiode Array Area
(Note B)
300
50
CL of Solder Contacts
20 Nominal
140 Nominal
ni
750 150
Lead Free
All linear dimensions are in micrometers. Dimension tolerance is ± 20 μm unless otherwise noted.
The die is centered within the package within a tolerance of ± 3 mils.
Package top surface is molded with an electrically nonconductive clear plastic compound having an index of refraction of 1.55.
Contact finish is copper alloy A194 with pre-plated NiPdAu lead finish.
This package contains no lead (Pb).
This drawing is subject to change without notice.
Te
NOTES: A.
B.
C.
D.
E.
F.
CL of Photodiode Array Area (Note B)
Pb
ch
PIN 1
ca
CL of Solder Contacts
Figure 19. Package FN — Dual Flat No-Lead Packaging Configuration
The LUMENOLOGY r Company
Copyright E 2011, TAOS Inc.
r
r
www.taosinc.com
27
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
MECHANICAL DATA
TOP VIEW
2.00 0.05
1.75
1.50
4.00
al
id
4.00
B
+ 0.30
8.00
− 0.10
1.00
0.25
DETAIL A
B
A
am
lc s
on A
te G
nt
st
il
A
lv
3.50 0.05
DETAIL B
5 Max
5 Max
0.254
0.02
2.18 0.05
Ao
2.18 0.05
0.83 0.05
Bo
All linear dimensions are in millimeters. Dimension tolerance is ± 0.10 mm unless otherwise noted.
The dimensions on this drawing are for illustrative purposes only. Dimensions of an actual carrier may vary slightly.
Symbols on drawing Ao, Bo, and Ko are defined in ANSI EIA Standard 481−B 2001.
Each reel is 178 millimeters in diameter and contains 3500 parts.
TAOS packaging tape and reel conform to the requirements of EIA Standard 481−B.
In accordance with EIA standard, device pin 1 is located next to the sprocket holes in the tape.
This drawing is subject to change without notice.
Te
ch
NOTES: A.
B.
C.
D.
E.
F.
G.
ni
ca
Ko
Copyright E 2011, TAOS Inc.
Figure 20. Package FN Carrier Tape
The LUMENOLOGY r Company
r
r
28
www.taosinc.com
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
MANUFACTURING INFORMATION
The FN package has been tested and has demonstrated an ability to be reflow soldered to a PCB substrate.
Table 17. Solder Reflow Profile
PARAMETER
REFERENCE
DEVICE
Average temperature gradient in preheating
tsoak
2 to 3 minutes
Time above 217°C (T1)
t1
Max 60 sec
Time above 230°C (T2)
t2
Max 50 sec
Time above Tpeak −10°C (T3)
t3
Max 10 sec
Tpeak
260°C
am
lc s
on A
te G
nt
st
il
Peak temperature in reflow
lv
Soak time
2.5°C/sec
Temperature gradient in cooling
Max −5°C/sec
Not to scale — for reference only
T3
T2
t3
t2
tsoak
t1
Figure 21. Solder Reflow Profile Graph
Te
ch
Time (sec)
ni
Temperature (C)
T1
ca
Tpeak
al
id
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.
The LUMENOLOGY r Company
Copyright E 2011, TAOS Inc.
r
r
www.taosinc.com
29
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
MANUFACTURING INFORMATION
Moisture Sensitivity
al
id
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 FN package has been assigned a moisture sensitivity level of MSL 3 and the devices should be stored under
the following conditions:
5°C to 50°C
60% maximum
12 months from the date code on the aluminized envelope — if unopened
168 hours or fewer
lv
Temperature Range
Relative Humidity
Total Time
Opened Time
Te
ch
ni
ca
am
lc s
on A
te G
nt
st
il
Rebaking will be required if the devices have been stored unopened for more than 12 months or if the aluminized
envelope has been open for more than 168 hours. If rebaking is required, it should be done at 50°C for 12 hours.
Copyright E 2011, TAOS Inc.
The LUMENOLOGY r Company
r
r
30
www.taosinc.com
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS100B − FEBRUARY 2011
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
al
id
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).
am
lc s
on A
te G
nt
st
il
lv
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.
ca
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.
Te
ch
ni
LUMENOLOGY, TAOS, the TAOS logo, and Texas Advanced Optoelectronic Solutions are registered trademarks of Texas Advanced
Optoelectronic Solutions Incorporated.
The LUMENOLOGY r Company
Copyright E 2011, TAOS Inc.
r
r
www.taosinc.com
31
TSL2771
LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
Te
ch
ni
ca
am
lc s
on A
te G
nt
st
il
lv
al
id
TAOS100B − FEBRUARY 2011
Copyright E 2011, TAOS Inc.
The LUMENOLOGY r Company
r
r
32
www.taosinc.com