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PDF ( 数据手册 , 数据表 ) SFH7770E6

零件编号 SFH7770E6
描述 Ambient Light and Proximity Sensor
制造商 OSRAM
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SFH7770E6 数据手册, 描述, 功能
SFH 7770 E6
Ambient Light and Proximity Sensor
1 Abstract
This application note describes technical
details and provides some application
guidelines for the combined ambient light
and proximity sensor SFH 7770 E6.
Compared to its predecessors (SFH 7770
E4 and E5), the SFH 7770 E6 features a
mores sensitive proximity sensor (up to
five times improved sensitivity) and
improved ambient light sensor (sensitive
down to 0.03 lx).
The document starts with a general
introduction to the device, followed by a brief
overview on the features (Sec. 2) and
operating modes (Sec. 3) of the sensor. The
integration and operation of the sensor in an
I²C bus environment is described in Sec. 4,
whereas Sec. 5 covers the interrupt
capabilities of the SFH 7770 E6.
Sec. 6 provides a functional description of
the sensor. Optical design guidelines and
application relevant information are given in
Sec. 7 followed by the guidelines for the
electrical design in Sec. 8. Finally Sec. 9
presents a sample software code.
More general information about ambient
light sensing, technical data and I²C bus are
available in the following documents:
- OSRAM OS general application note
on ambient light sensing [1]
- SFH 7770 E6 datasheet [2]
- I²C bus specification [3]
- Driving a LED with an external driver
(> 200 mA) application note [4]
2 Introduction
The SFH 7770 E6 is a compact device
which is designed for simultaneous
Fig. 1: Ambient Light and Proximity
Sensor SFH 7770 E6.
detection of ambient light and proximity of
reflecting objects. Applications are mobile
phones, PDAs, notebooks, cameras and
other consumer products.
The device includes the following features:
Proximity Sensor (PS)
- Detection-range up to 200 mm
- Gesture recognition possible
- Outputs to drive up to three IR
emitters
- Optimized for 850 nm emitters
- Immune to ambient light
Ambient Light Sensor (ALS)
- 0.03lx - 65000lx- High linearity
- Spectral sensitivity well matched to
the human eye
I2C interface
- 100 kHz / 400 kHz and 3.4 MHz
mode
- 3 programmable measurement
modes (STAND-BY, TRIGGERED,
FREE-RUNNING)
Current consumption < 5 μA in
STAND-BY mode
Small package size, 2.8 x 2.8 x 0.9
mm³
February 27, 2012
page 1 of 33







SFH7770E6 pdf, 数据表
PS CONTROL: Control of proximity sensor
R/W-Register 0x81
Bit 7 6
default XXXXXX
54
not used
3
21
0
mode of Proximity Sensor
00 STAND-BY
00 STAND-BY
01 STAND-BY
10 TRIGGERED by MCU
11 FREE-RUNNING (internally triggered)
I_LED_1 and I_LED_2: Activation of LED and Emitter (LED 1 and LED 2) current setting
The register allows the activation of the LEDs. The following combinations of active LEDs are available: LED 1, LED 1 + LED 2, LED
1 + LED 3 and LED 1 + LED 2 + LED 3. In addition the LED pulse currents for LED 1 and LED 2 can be set.
R/W-Register 0x82
Bit 7 6 5 4 3
activation of LEDs setting LED_2 pulse current
Default 00
011 50 mA
00 LED 1 active
000 5 mA
01 LED 1 and 2 active 001 10 mA
10 LED 1 and 3 active 010 20 mA
11 all LEDs active 011 50 mA
100 100 mA
101 150 mA
110 200 mA
210
setting LED_1 pulse current
011 50 mA
000 5 mA
001 10 mA
010 20 mA
011 50 mA
100 100 mA
101 150 mA
110 200 mA
I_LED_3: Emitter (LED 3) current setting
R/W-Register 0x83
Bit 7
Not used
Default XXXXX
6
5
4
3210
setting LED_3 pulse current
011 50 mA
000 5 mA
001 10 mA
010 20 mA
011 50 mA
100 100 mA
101 150 mA
110 200 mA
ALS & PS TRIG: MCU-triggered measurement (for ambient light sensor and proximity sensor)
If „1“ is set a new measurement will start after I2C stop command from MCU. As soon as the measurement is finished the
corresponding bit of the register will automatically be set to „0“ by the SFH 7770 E6.
R/W-Register 0x84
Bit 7 6 5 4
not used
default XXXXXX
3
21
trigger ambient light
1
0
trigger proximity
1
February 27, 2012
page 8 of 33







SFH7770E6 equivalent, schematic
Fig. 11: LED current and timing during one
proximity measurement cycle (LED
integration time setting to 750 us).
Cover
Transmission
(at 850 nm)
100 % (no glass)
90 % (clear glass)
80 %
70 %
corresponding
detection distance
(approximation)
100 %
90 %
80 %
70 %
Tab. 9: Impact of cover glass (IR-)
transmission on PS detection range.
integration time tburst, LED current and the
size / reflection properties of the target.
6.2.2 PS Signal and Detection Range
The strength of the reflected proximity signal
and hence the output reading of the PS
depends on the current setting of the LEDs.
Large detection ranges are obtained for LED
currents 100 mA, 150 mA or 200 mA.
Fig. 12 and 13 present the proximity values
vs. distance for a 100 x 100 mm2 Kodak
White (90% reflectivity) target. The emitter
(SFH 4650) was placed 5 mm away from
the SFH 7770 E6.
As indicated by Fig. 12 and 13, the above
setup allows a maximum detection range of
about 20 cm (by using e.g. 200 mA LED
current with SFH 4650 and a PS integration
time of 1000 μs). Larger detection distances
might require the use of e.g. stacked LEDs
or LEDs with narrow and intense radiation
characteristics (e.g. lensed LEDs like SFH
4059).
Proximity Sensor Count vs. Target Distance
200 Kodak White, 90 %, 100 x 100 mm2
180 Emitter: SFH 4650
160
140
120
100
100 mA
80 150 mA
60 200 mA
0 50 100 150 200
Target Distance / mm
Fig. 12: Proximity sensor signal count vs.
target distance and LED drive current (PS
integration time tburst = 750 us) – one LED
SFH 4650 on.
Proximity Sensor Count vs. Target Distance
200 Kodak White, 90 %, 100 x 100 mm2
180 Emitter: SFH 4650
160
140
120
100 300 us
80
750 us
1000 us
60 1500 us
0 50 100 150 200
Target Distance / mm
Fig. 13: Proximity sensor signal count vs. PS
integration time tburst (LED currnet = 100 mA) –
one LED SFH 4650 on.
If used as a pure proximity switch it is
recommended to set the threshold level not
below 80 counts to avoid interference with
noise.
As a rule of thumb, 30 counts result in
almost a quadrupling in irradiance (PS
signal level) whereas 10 counts represent
roughly a factor of 1.55 in analog signal
level. As a general rule OSRAM
recommends for a robust design the setting
of the threshold levels to be up to around 10
times above any noise level. The factor 10
February 27, 2012
page 16 of 33










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