Ambient Light Sensor IC Series
Digital 16bit Serial Output Type
Ambient Light Sensor IC
BH1721FVC
No.11046EBT10
●Descriptions
2
BH1721FVC is an digital Ambient Light Sensor IC for I C bus interface. This IC is the most suitable to obtain the ambient
light data for adjusting LCD and Keypad backlight power of Mobile phone. It is possible to detect wide range at High
resolution. ( 1 - 65528 lx ).
●Features
2
1) I C bus Interface ( f / s Mode Support, Slave Address : "0100011" )
2) Spectral responsibility is approximately human eye response
3) Illuminance to Digital Converter
4) Wide range and High resolution. (1 – 65528 lx )
5) Low Current by power down function
6) 50Hz / 60Hz Light noise reject-function
7) 1.8V Logic input interface
8) No need any external parts
9) Light source dependency is little. (ex. Incandescent Lamp. Fluorescent Lamp. Halogen Lamp. White LED. Sun Light)
10) Small measurement variation (+/- 15%)
11) Compact surface mount package 1.6 x 1.6 x 0.55 mm
●Applications
Mobile phone, LCD TV, NOTE PC, Portable game machine, Digital camera, Digital video camera, PDA,
LCD display
●Absolute
Maximum Ratings
Parameter
Supply Voltage
Operating Temperature
Storage Temperature
SDA Sink Current
Power Dissipation
Symbol
Vmax
Topr
Tstg
Imax
Pd
Ratings
4.5
-40½85
-40½100
7
165
※
Units
V
℃
℃
mA
mW
※70mm ×
70mm
×
1.6mm glass epoxy board. Derating in done at 2.2mW/℃ for operating above Ta=25℃.
●Operating
Conditions
Parameter
VCC Voltage
I C Reference Voltage
2
Symbol
Vcc
V
DVI
Ratings
Min.
2.4
1.65
Typ.
3.0
-
Max.
3.6
V
CC
Units
V
V
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© 2011 ROHM Co., Ltd. All rights reserved.
1/15
2011.11 - Rev.B
BH1721FVC
●Electrical
Characteristics ( VCC = 3.0V, DVI = 3.0V, Ta = 25℃, unless otherwise noted )
Limits
Parameter
Symbol
Units
Min.
Typ.
Max.
Supply Current
Powerdown Current
Peak Wave Length
Measurement Accuracy
Dark ( 0 lx ) Sensor out
H-Resolution Mode Resolution
L-Resolution Mode Resolution
H-Resolution Mode
Measurement Time
L-Resolution Mode
Measurement Time
Incandescent /
Fluorescent Sensor out ratio
DVI Input ‘L’ Voltage
SCL, SDA Input ‘H’ Voltage 1
SCL, SDA Input ‘H’ Voltage 2
SCL, SDA Input ‘L’ Voltage 1
SCL, SDA Input ‘L’ Voltage 2
SCL, SDA, Input ‘H’ Current
SCL, SDA, Input ‘L’ Current
I
2
C SCL Clock Frequency
I
2
C Bus Free Time
I
2
C Hold Time ( repeated )
START Condition
I
2
C Set up time
for a Repeated START Condition
I
2
C Set up time
for a Repeated STOP Condition
I
2
C Data Hold Time
I
2
C Data Valid Time
I
2
C Data Valid Acknowledge Time
I
2
C Data Setup Time
I
2
C ‘L’ Period of the SCL Clock
I
2
C ‘H’ Period of the SCL Clock
I
2
C SDA Output ‘L’ Voltage
Icc1
Icc2
λp
S/A
S0
rHR
rLR
tHR
tLR
rIF
VDVL
VIH1
VIH2
VIL1
VIL2
IIH
IIL
fSCL
tBUF
tHDSTA
tSUSTA
tSUSTO
tHDDAT
tVDDAT
tVDACK
tSUDAT
tLOW
tHIGH
VOL
－
－
－
1.02
0
－
－
－
－
－
－
0.7 * DVI
1.26
－
－
－
－
－
1.3
0.6
0.6
0.6
0
－
－
100
1.3
0.6
0
140
0.01
560
1.2
0
1
8
120
16
1
－
－
－
－
－
－
－
－
－
－
－
－
－
－
－
－
－
－
－
199
1.0
－
1.38
2
－
－
180
24
－
0.4
－
－
0.3 * DVI
DVI – 1.26
10
10
400
－
－
－
－
－
0.9
0.9
－
－
－
0.4
µA
µA
nm
times
count
lx
lx
ms
ms
times
V
V
V
V
V
µA
µA
kHz
µs
µs
µs
µs
µs
µs
µs
ns
µs
µs
V
Technical Note
Conditions
Ev = 100 lx
※
1
No input Light
Sensor out / Actual lx
1, 2
EV = 1000 lx
※ ※
H-Resolution Mode
※
3
EV = 1000 lx
DVI
≧
1.8V
1.65V
≦
DVI
＜
1.8V
DVI
≧
1.8V
1.65V
≦
DVI
＜
1.8V
IOL = 3 mA
※1
White LED is used as optical source.
※2
Measurement Accuracy typical value is possible to change '1' by "Measurement result adjustment function".
※3
Use H-Resolution Mode if dark data ( less than 20 lx ) is need.
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© 2011 ROHM Co., Ltd. All rights reserved.
2/15
2011.11 - Rev.B
BH1721FVC
●Reference
Data
1.2
1.0
0.8
Technical Note
64
56
100000
40
32
24
16
8
Measurement Result
32
40
48
56
64
Measurement Result
48
10000
Ratio
1000
0.6
0.4
0.2
0.0
400
500
600
700
800
900
1000
1100
H-Res.
L-Res.
100
10
0
0
8
16
Wavelength [ nm ]
Illuminance [ lx ]
24
1
1
10
100
1000
10000 100000
Fig.1 Spectral Response
1.2
1
1.2
1
Fig.2 Illuminance -
Measurement Result 1
10
Fig.3 Illuminance -
Measuremnet Result 2
Illuminance [ lx ]
0.8
-
+
0.8
Measurement Result
1pin
Ratio
0.6
0.4
0.2
0
-90
-60
-30
0
30
60
90
8
Ratio
+
0.6
-
-
6
1pin
-
+
0.4
0.2
0
-90
-60
-30
0
30
60
90
4
+
+
2
H-Res.
0
-40
-20
0
20
40
60
80
100
Angle [ deg ]
Angle [ deg ]
Ta [
℃
]
Fig.4 Directional Characteristics 1
1.2
1
0.8
Fig.5 Directional Characteristics 2
200
Fig.6 Dark Response
Fluorescent Light
Incandescent
Light
Halogen Light
ICC @ Measurement
150
Ratio
0.6
Kripton Light
100
0.4
0.2
0
-40
-20
0
20
40
60
80
100
Artifical Sun
Light
White LED
50
0
Ta [
℃
]
0
0.5
Ratio
1
1.5
2
2
2.5
3
VCC [ V ]
3.5
4
Fig.7 Measurement Result
Temperature Dependency
10
Fig.8 Light Source Dependency
(Fluorescent Light is set to ‘1’)
1.2
Fig.9 VCC – ICC
(During measurement)
1.2
1
ICC @ POWER DOWN [ uA ]
1
DVI=1.8V
1
VCC=3V
0.8
0.8
Ratio
Ratio
0.6
0.6
0.4
0.2
0
0.1
0.4
0.2
0.01
-40
-20
0
20
40
60
80
100
0
2
2.5
3
3.5
4
1.5
2
2.5
3
3.5
Ta [
℃
]
VCC [ V ]
DVI [ V ]
Fig.10 VCC – ICC@0 lx
(POWER DOWN)
Fig.11 Measurement Result
VCC Dependency
Fig.12 Measurement Result
DVI Dependency
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© 2011 ROHM Co., Ltd. All rights reserved.
3/15
2011.11 - Rev.B
BH1721FVC
●Block
Diagram
VCC
DVI
Technical Note
AMP
ADC
Logic
+
I
2
C Interface
SCL
SDA
PD
OSC
GND
●Block
Diagram Descriptions
・PD
Photo diode with approximately human eye response.
・AMP
Integration-OPAMP for converting from PD current to Voltage.
・ADC
AD converter for obtainment Digital 16bit data.
2
・Logic
+ I C Interface
Ambient Light Calculation and I
2
C BUS Interface. It is including below register.
Data Register
→
This is for registration of Ambient Light Data. Initial Value is "0000_0000_0000_0000".
Measurement Time Register
→
This is for registration of measurement time. Initial Value is "01_0010_1100".
・OSC
Internal Oscillator. It is CLK for internal logic.
●Measurement
Procedure
Power supply
Initial state is Power Down mode after
VCC and DVI supply.
Power Down
Power On
Measurement command
State Transition by I
2
C write-command.
Automatically State Transition
Continuous measurement
* "Power On" Command is possible to omit.
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© 2011 ROHM Co., Ltd. All rights reserved.
4/15
2011.11 - Rev.B
BH1721FVC
●Instruction
Set Architecture
Instruction
Power Down
Power On
Continuously Auto-Resolution Mode
Continuously H-Resolution Mode
Technical Note
Opecode
0000_0000
0000_0001
0001_0000
0010_0000
0001_0010
0010_0010
0001_0011
0001_0110
0010_0011
0010_0110
010_MT[9,8,7,6,5]
011_MT[4]_XXXX
No active state.
Comments
Waiting for measurement command.
Switch measurement mode automatically by illuminance.
Start measurement at 1lx resolution.
Measurement Time is typically 120ms.
Start measurement at 8lx resolution.
Measurement Time is typically 16ms.
Change measurement time.
※
Please refer "adjust measurement result for influence of optical window."
Continuously L-Resolution Mode
Change Measurement time
( High bit )
Change Masurement time
( Low bit )
※
Don't input the other opecode.
Change measurement time.
※
Please refer "adjust measurement result for influence of optical window."
●Measurement
mode explanation
Measurement Mode
Measurement Time.
H-Resolution Mode
L-Resolution Mode
Typ. 120ms
Typ. 16ms
Measurement Range.
0 - 8191 lx
0 - 65528 lx
Resolution
1 lx
8 lx
We recommend to use H-Resolution Mode.
Measurement time (integration time) of H-Resolution Mode is so long that some kind of noise (including in 50Hz / 60Hz
noise) is rejected. And H-Resolution Mode is 1 lx resolution so that it is suitable for darkness (less than 20 lx)
Auto-Resolution mode selects measurement mode automatically. It is determined after 16ms (typ.) passes from
measurement start. If BH1721FVC judges that current illuminance is more than 4000 lx, then Data is output at L-resolution
mode, else Data is output after 120ms(typ.) from measurement start at H-resolution mode. Please refer below flow chart.
Start
after 16ms.(typ.)
Select mode
Lux <= 4000
Lux > 4000
DATA output at L-resolution mode
Data output at H-resolution mode after
120ms passes from measurement start.
Auto-Resolution mode measurement
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© 2011 ROHM Co., Ltd. All rights reserved.
5/15
2011.11 - Rev.B
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