ROHM BH1721FVC Technical data
Ambient Light Sensor IC Series
Digital 16bit Serial Output Type
Ambient Light Sensor IC
BH1721FVC
●Descriptions
BH1721FVC is an digital Ambient Light Sensor IC for I
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
●Applications
●Absolute Maximum Ratings
2
1) I
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
Mobile phone, LCD TV, NOTE PC, Portable game machine, Digital camera, Digital video camera, PDA,
LCD display
C bus Interface ( f / s Mode Support, Slave Address : "0100011" )
2
C bus interface. This IC is the most suitable to obtain the ambient
No.11046EBT10
Parameter Symbol Ratings Units
Supply Voltage Vmax 4.5 V
Operating Temperature Topr -40～85 ℃
Storage Temperature Tstg -40～100 ℃
SDA Sink Current Imax 7 mA
Power Dissipation Pd 165※ mW
※70mm × 70mm × 1.6mm glass epoxy board. Derating in done at 2.2mW/℃ for operating above Ta=25℃.
●Operating Conditions
Parameter Symbol
VCC Voltage Vcc 2.4 3.0 3.6 V
I2C Reference Voltage VDVI 1.65 - VCC V
Min. Typ. Max.
Ratings
Units
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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 )
Parameter
Supply Current
Symbol
Min. Typ. Max.
Icc1 － 140 199 µA Ev = 100 lx
Limits
Technical Note
Units Conditions
1
※
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
Icc2 － 0.01 1.0 µA No input Light
λp － 560 － nm
S/A 1.02 1.2 1.38 times
S0 0 0 2 count H-Resolution Mode
Sensor out / Actual lx
EV = 1000 lx
※
1, ※2
3
※
rHR － 1 － lx
rLR － 8 － lx
tHR － 120 180 ms
tLR － 16 24 ms
rIF － 1 － times EV = 1000 lx
VDVL － － 0.4 V
VIH1 0.7 * DVI － － V DVI ≧ 1.8V
VIH2 1.26 － － V 1.65V ≦ DVI ＜ 1.8V
VIL1 － － 0.3 * DVI V DVI ≧ 1.8V
SCL, SDA Input ‘L’ Voltage 2
SCL, SDA, Input ‘H’ Current
SCL, SDA, Input ‘L’ Current
I2C SCL Clock Frequency
I2C Bus Free Time
I2C Hold Time ( repeated )
START Condition
I2C Set up time
for a Repeated START Condition
I2C Set up time
for a Repeated STOP Condition
I2C Data Hold Time
I2C Data Valid Time
I2C Data Valid Acknowledge Time
I2C Data Setup Time
I2C ‘L’ Period of the SCL Clock
VIL2 － － DVI – 1.26 V 1.65V ≦ DVI ＜ 1.8V
IIH － － 10 µA
IIL － － 10 µA
fSCL － － 400 kHz
tBUF 1.3 － － µs
tHDSTA 0.6 － － µs
tSUSTA 0.6 － － µs
tSUSTO 0.6 － － µs
tHDDAT 0 － － µs
tVDDAT － － 0.9 µs
tVDACK － － 0.9 µs
tSUDAT 100 － － ns
tLOW 1.3 － － µs
I2C ‘H’ Period of the SCL Clock
I2C SDA Output ‘L’ Voltage
※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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tHIGH 0.6 － － µs
VOL 0 － 0.4 V IOL = 3 mA
2/15
2011.11 - Rev.B
BH1721FVC
●Reference Data
1.2
1.0
0.8
0.6
Ratio
0.4
0.2
0.0
400 500 600 700 800 900 1000 1100
1.2
Wave length [ nm ]
Fig.1 Spectral Response
1
0.8
0.6
Ratio
0.4
0.2
0
-90 -60 -30 0 30 60 90
Fig.4 Directional Characteristics 1
1.2
1
0.8
0.6
Ratio
0.4
0.2
0
-40-20 0 20406080100
1pin
-
-
Angle [ deg ]
Ta [ ℃ ]
+
+
Fig.7 Measurement Result
Temperature Dependency
10
1
0.1
ICC @ POWER DOWN [ uA ]
0.01
-40-20 0 20406080100
Fig.10 VCC – ICC@0 lx
(POWER DOWN)
Ta [ ℃ ]
64
56
48
40
32
H-Res.
24
Measurement Result
16
8
0
0 8 16 24 32 40 48 56 64
L-Res.
Illuminance [ lx ]
Fig.2 Illuminance -
Measurement Result 1
1.2
1
0.8
0.6
Ratio
0.4
0.2
0
-90 -60 -30 0 30 60 90
-
+
Angle [ deg ]
-
1pin
+
Fig.5 Directional Characteristics 2
Fluor escent Light
Incandescent
Light
Halogen Light
Kripton Light
Artifical Sun
Light
White LED
0 0.5 1 1.5 2
Ratio
Fig.8 Light Source Dependency
(Fluorescent Light is set to ‘1’)
1.2
1
0.8
0.6
Ratio
0.4
0.2
0
2 2.5 3 3.5 4
DVI=1.8V
VCC [ V ]
Fig.11 Measurement Result
VCC Dependency
Technical Note
100000
10000
1000
100
Measurement Result
10
1
1 10 100 1000 10000 100000
Illuminance [ lx ]
Fig.3 Illuminance -
Measuremnet Result 2
10
8
6
4
Measurement Result
2
H-Res.
0
-40 -20 0 20 40 60 80 100
Fig.6 Dark Response
200
150
100
50
ICC @ Measurement
0
2 2.5 3 3.5 4
(During measurement)
1.2
1
0.8
0.6
Ratio
0.4
0.2
0
1.5 2 2.5 3 3.5
Fig.12 Measurement Result
DVI Dependency
Ta [ ℃ ]
VCC [ V ]
Fig.9 VCC – ICC
VCC=3V
DVI [ V ]
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© 2011 ROHM Co., Ltd. All rights reserved.
3/15
2011.11 - Rev.B
BH1721FVC
●Block Diagram
●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
・OSC
●Measurement Procedure
Measurement command
Continuous measurement
C Interface
Ambient Light Calculation and I2C 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".
Internal Oscillator. It is CLK for internal logic.
Power supply
Power Down
Power On
VCC
AMP
PD
Initial state is Power Down mode after
VCC and DVI supply.
ADC
OSC
GND
DVI
Logic
+
I2C Interface
State Transition by I2C write-command.
Automatically State Transition
Technical Note
SCL
SDA
* "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 Opecode Comments
Power Down 0000_0000 No active state.
Power On 0000_0001 Waiting for measurement command.
Technical Note
Continuously Auto-Resolution Mode
Continuously H-Resolution Mode
Continuously L-Resolution Mode
Change Measurement time
( High bit )
Change Masurement time
( Low bit )
※ Don't input the other opecode.
●Measurement mode explanation
Measurement Mode Measurement Time. Measurement Range. Resolution
H-Resolution Mode Typ. 120ms
L-Resolution Mode Typ. 16ms
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.
Data output at H-resolution mode after
120ms passes from measurement start.
Lux <= 4000
Start
Select mode
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
0 - 65528 lx 8 lx
after 16ms.(typ.)
Lux > 4000
DATA output at L-resolution mode
Auto-Resolution mode measurement
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."
Change measurement time.
※ Please refer "adjust measurement result for influence of optical window."
0 - 8191 lx 1 lx
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© 2011 ROHM Co., Ltd. All rights reserved.
5/15
2011.11 - Rev.B
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