Rohm BH1715FVC Specification sheet

TECHNICAL NOTE
Ambient Light Sensor IC Series
Digital 16bit Serial Output Type
Ambient Light Sensor IC
BH1715FVC
●Descriptions
BH1715FVC is an digital Ambient Light Sensor IC for I2C 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 - 65535 lx ).
●Features
1) I2C bus Interface （f / s Mode Support ）
2) Spectral responsibility is approximately human eye response
3) Illuminance to Digital Converter
4) Wide range and High resolution. （1 – 65535 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) It is possible to select 2 type of I2C slave-address.
11) Adjustable measurement result for influence of optical window ( It is possible to detect min. 0.33 lx, max. 100000 lx by
using this function. )
12) Small measurement variation (+/- 15%)
●Applications
Mobile phone, LCD TV, NOTE PC, Portable game machine, Digital camera, Digital video camera, Car navigation, PDA,
LCD display
●Absolute Maximum Ratings
Parameter Symbol Limits 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 260※mW
※ 70mm × 70mm × 1.6mm glass epoxy board. Derating in done at 3.47mW/℃ for operating above Ta=25℃.
●Operating Conditions
Parameter Symbol Min. Typ. Max. Units
VCC Voltage Vcc 2.4 3.0 3.6 V
I2C Reference Voltage VDVI 1.65 －VCC V
June 2008
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●Electrical Characteristics ( VCC = 3.0V, DVI = 3.0V, Ta = 25℃, unless otherwise noted )
Parameter Symbol Min. Typ. Max. Units Conditions
Supply Current Icc1 －120 190 uA Ev = 100 lx ※1
Powerdown Current Icc2 －0.01 1.0 uA No input Light
Peak Wave Length λp －560 －nm
Measurement Accuracy S/A 1.02 1.2 1.38 times
Sensor out / Actual lx
EV = 1000 lx ※1, ※2
Dark ( 0 lx ) Sensor out S0 0 0 2 count H-Resolution Mode ※3
H-Resolution Mode Resolution rHR －1 －lx
L-Resolution Mode Resolution rLR －4 －lx
H-Resolution Mode Measurement
Time tHR －120 180 ms
L-Resolution Mode Measurement
Time tLR －16 24 ms
Incandescent / Fluorescent Sensor
out ratio rIF －1 －times
EV = 1000 lx
ADDR Input ‘H’ Voltage VAH 0.7 * VCC －－V
ADDR Input ‘L’ Voltage VAL －－0.3 * VCC V
DVI Input ‘L’ Voltage VDVL －－0.4 V
SCL, SDA Input ‘H’ Voltage 1 VIH1 0.7 * DVI －－V DVI ≧1.8V
SCL, SDA Input ‘H’ Voltage 2 VIH2 1.26 －－V 1.65V ≦DVI ＜1.8V
SCL, SDA Input ‘L’ Voltage 1 VIL1 －－0.3 * DVI V DVI ≧1.8V
SCL, SDA Input ‘L’ Voltage 2 VIL2 －－DVI – 1.26 V 1.65V ≦DVI ＜1.8V
SCL, SDA, ADDR Input ‘H’ Current IIH －－10 uA
SCL, SDA, ADDR Input ‘L’ Current IIL －－10 uA
I2C SCL Clock Frequency fSCL －－400 kHz
I2C Bus Free Time tBUF 1.3 －－us
I2C Hold Time ( repeated ) START
Condition tHDSTA 0.6 －－us
I2C Set up time for a Repeated
START Condition tSUSTA 0.6 －－us
I2C Set up time for a Repeated
STOP Condition tSUSTD 0.6 －－us
I2C Data Hold Time tHDDAT 0 －0.9 us
I2C Data Setup Time tSUDAT 100 －－ns
I2C ‘L’ Period of the SCL Clock tLOW 1.3 －－us
I2C ‘H’ Period of the SCL Clock tHIGH 0.6 －－us
I2C SDA Output ‘L’ Voltage VOL 0 －0.4 V IOL = 3 mA
※1White 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 10 lx ) is need.
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●Reference Data
Fig.8 Light Source Dependency
( Fluorescent Light is set to '1' )
1
10
100
1000
10000
100000
1 10 100 1000 10000 100000
Illuminance [ lx ]
Measurement Result
Fig.4 Directional Characteristics 1 Fig.5 Directional Characteristics 2 Fig.6 Dark Response
蛍光灯白熱灯感度比
VCC vs. ICC@測定
中
受信指向角特性
0
0.2
0.4
0.6
0.8
1
1.2
-90 -60 -30 0 30 60 90
Angle [ deg ]
Ratio
0
0.2
0.4
0.6
0.8
1
1.2
-90 -60 -30 0 30 60 90
Angle [ deg ]
Ratio
0
2
4
6
8
10
-40 -10 20 50 80 110
Ta [ ℃]
Measurement Result
0
50
100
150
200
2 2.5 3 3.5 4
VCC [ V ]
ICC @ Measurement
00.511.52
Fluorescent
Light
Incandescent
Light
Halogen
Light
Kripton Light
Artifical Sun
Light
White LED
Ratio
H-Res. L-Res.
0
8
16
24
32
40
48
56
64
0 8 16 24 32 40 48 56 64
Illuminance [ lx ]
Measurement Result
H-Res.
L-Res.
H-Res.
-
+
-
+
-
+
-
+
1pin
1pin
0
0.2
0.4
0.6
0.8
1
1.2
400 500 600 700 800 900 1000 1100
Wavelength [ nm ]
Ratio
Fig.7 Measurement Result
Temperature Dependency
Fig.2 Illuminance –
Measurement Result 1
Fig.3 Illuminance –
Measurement Result 2
Fig.9 VCC – ICC
( During measurement )
Fig.10 VCC – ICC@0 Lx
( POWER DOWN )
Fig.1 Spectral Response
0
0.2
0.4
0.6
0.8
1
1.2
22.533.54
VCC [ V ]
Ratio
Fig.11 Measurement Result
VCC Dependency
0
0.2
0.4
0.6
0.8
1
1.2
1.5 2 2.5 3 3.5
DVI [ V ]
Ratio
Fig.12 Measurement Result
DVI Dependency
DVI=1.8V VCC=3V
0.01
0.1
1
10
-40 -20 0 20 40 60 80
Ta [ ℃]
ICC @ POWER DOWN [ uA ]
0
0.2
0.4
0.6
0.8
1
1.2
-40 -10 20 50 80 110
Ta [ ℃]
Ratio
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●Block Diagram
●Block Diagram Descriptions
zPD
Photo diode with approximately human eye response.
zAMP
Integration-OPAMP for converting from PD current to Voltage.
zADC
AD converter for obtainment Digital 16bit data.
zLogic + I2C 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 "0100_0101".
zOSC
Internal Oscillator ( typ. 320kHz ). It is CLK for internal logic.
●Measurement Procedure
* "Power On" Command is possible to omit.
SCL
SDA
GND ADDR
PD
VCC DVI
Logic
+
I2C Interface
ADC
AMP
OSC
State Transition by I2C write-command.
Automatically State Transition
State is automatically changed to
Power Down mode.
Power supply
Power Down
Power On
Measurement Command
Initial state is Power Down mode after
VCC and DVI supply.
One Time Measurement Continuous Measurement
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●Instruction Set Architecture
Instruction Opecode Comments
Power Down 0000_0000 No active state.
Power On 0000_0001 Waiting for measurement command.
Reset 0000_0111
Reset Data register value. Reset command is not acceptable in
Power Down mode.
Continuously H-Resolution Mode 0001_0000
Start measurement at 1lx resolution.
Measurement Time is typically 120ms.
Continuously L-Resolution Mode 0001_0011
Start measurement at 4lx resolution.
Measurement Time is typically 16ms.
One Time H-Resolution Mode 0010_0000
Start measurement at 1lx resolution.
Measurement Time is typically 120ms.
It is automatically set to Power Down mode after measurement.
One Time L-Resolution Mode 0010_0011
Start measurement at 4lx resolution.
Measurement Time is typically 16ms.
It is automatically set to Power Down mode after measurement.
Change Measurement time
( High bit ) 01000_MT[7,6,5]
Change measurement time.
※Please refer "adjust measurement result for influence of optical
window."
Change Measurement time
( Low bit ) 011_MT[4,3,2,1,0]
Change measurement time.
※Please refer "adjust measurement result for influence of optical
window."
※Don't input the other opecode.
●Measurement mode explanation
Measurement Mode Measurement Time. Resolution
H-Resolution Mode Typ. 120ms. 1 Lx.
L-Resolution Mode Typ. 16ms. 4 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 l x resolution so that it is suitable for darkness ( less than 10 lx )
●Explanation of Asynchronous reset and Reset command "0000_0111"
1) Asynchronous reset
All registers are reset. It is necessary on power supply sequence. Please refer "Timing chart for VCC and DVI power supply
sequence" in this page. It is power down mode during DVI = 'L'.
2) Reset command
Reset command is for only reset Illuminance data register. ( reset value is '0' ) It is not necessary even power supply
sequence. It is used for removing previous measurement result. This command is not working in power down mode, so that
please set the power on mode before input this command.
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●Timing chart for VCC and DVI power supply sequence
DVI is I2C bus reference voltage terminal. And it is also asynchronous reset terminal. It is necessary to set to 'L' after VCC
is supplied. In DVI 'L' term, internal state is set to Power Down mode.
１） Recommended Timing chart1 for VCC and DVI supply.
２） Timing chart2 for VCC and DVI supply.
（If DVI rises within 1us after VCC supply ）
VCC
DVI
Reset Term ( more than 1us )
VCC
DVI
Don't care state
ADDR, SDA, SCL is not stable if DVI 'L' term ( 1us ) is not given by systems.
In this case, please connect the resisters ( approximately 100kOhm ) to ADDR without directly
connecting to VCC or GND,
Reset Term ( more than 1us )
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●Measurement sequence example from "Write instruction" to "Read measurement result"
ex1) Continuously H-resolution mode ( ADDR = 'L' )
①Send "Continuously H-resolution mode " instruction
ST 0100011 0 Ack 00010000 Ack SP
②Wait to complete 1st H-resolution mode measurement.( max. 180ms. )
③Read measurement result.
ST 0100011 1 Ack High Byte [ 15:8 ] Ack
Low Byte [ 7:0 ] Ack SP
How to calculate when the data High Byte is "10000011" and Low Byte is "10010000"
(2
15 + 29 + 28 + 27 + 24) / 1.2 ≒28067 [ lx ]
The result of continuously measurement mode is updated.( 120ms.typ at H-resolution mode, 16ms.typ at L-resolution
mode )
ex2 ) One time L-resolution mode ( ADDR = 'H' )
①Send "One time L-resolution mode " instruction
ST 1011100 0 Ack 00100011 Ack SP
②Wait to complete L-resolution mode measurement.( max. 24ms. )
③Read measurement result
ST 1011100 1 Ack High Byte [ 15:8 ] Ack
Low Byte [ 7:0 ] Ack SP
How to calculate when the data High Byte is "00000001" and Low Byte is "00010000"
(2
8 + 24) / 1.2 ≒227 [ lx ]
In one time measurement, Statement moves to power down mode after measurement completion. If updated result is
need then please resend measurement instruction.
from Master to Slave from Slave to Master
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●Application circuit example of DVI terminal
The DVI terminal is an asynchronous reset terminal. Please note that there is a possibility that IC doesn't operate normally if
the reset section is not installed after the start-up of VCC. (Please refer to the paragraph of "Timing chart for VCC and DVI
power supply sequence" )
The description concerning SDA and the terminal SCL is omitted in this application circuit example. Please design the
application the standard of the I2C bus as it finishes being satisfactory. Moreover, the description concerning the terminal
ADDR is omitted. Please refer to the paragraph of "Timing chart for VCC and DVI power supply sequence" about the
terminal ADDR design.
ex 1) The control signal line such as CPU is connected.
ex 2) Reset IC is used.
1, For Reset IC of the Push-Pull type
2, For Reset IC of the Open drain output
ex 3) A different power supply is used.
※Power supply of DVI must stand up later than power supply of VCC stand up, because it is necessary to secure reset section
( 1us or more ).
Micro
Controller
VCC
ADDR
SCL
SDA
0.1uF
0.1uF
DVI
GND
BH1715FVC
VCC
ADDR
SCL
SDA
0.1uF
DVI
GND
RESET
Reset IC( Push-Pull type )
BH1715FVC
0.1uF
VCC
ADDR
SCL
SDA
0.1uF
DVI
GND
Reset IC( Open drain type )
RESET
1kOhm
BH1715FVC
0
.1
u
F
BH1715FVC
VCC
ADDR
SCL
SDA 0.1uF
DVI
GND
0
.1
u
F
V2
V1
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ex 4) LPF using CR is inserted between VCC and DVI.
This method has the possibility that the Reset section of turning on the power supply can not satisfied. cannot be satisfied.
Please design the set considering the characteristic of the power supply enough.
Notes when CR is inserted between VCC and DVI
※Please note that there is a possibility that reset section ( 1us ) can not be satisfied because the power supply is turned on
when the rise time of VCC is slow
※When VCC is turned off, the DVI voltage becomes higher than VCC voltage but IC destruction is not occurred if
recommended constant ( R1 = 1kOhm, C1 = 1uF ) is used.
※Please note that there is a possibility that Reset section (1usec) cannot be satisfied if wait time is not enough long after
turning off VCC.(It is necessary to consider DVI voltage level after turning off VCC.)
Example of designing set when CR ( C = 1uF, R = 1kΩ) is inserted between VCC and DVI with VCC=2.8V
① The rise time to 0→2.4V of VCC must use the power supply of 100us or less.
② Please wait 25ms or more after VCC turn off ( VCC <= 0.05V ), because it is necessary to secure reset section ( 1us or more ).
R1 : 1kOhm
0.1uF C1 : 1uF
VCC
ADDR
GND
SCL
DVI
SDA
BH1715FVC
Reset Section : 1us or more
t1 VCC
DVI
2.4V
0.4V
0V
* Please do the application design to secure Reset section 1us or more after the reclosing of the power supply.
Reset Section : 1us or more
Rise time of
p
ower su
pp
l
y
: 100us or less
0.05V
Time to power supply reclosing : 25ms or more VCC
DVI
2.4V
0.4V
2.8V
0V
t2
* Please do the application design to secure Reset section 1us or more after the reclosing of the power supply.
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●I
2C Bus Access
1 ) I2C Bus Interface Timing chart
Write measurement command and Read measurement result are done by I2C Bus interface. Please refer the formally
specification of I2C Bus interface, and follow the formally timing chart.
2) Slave Address
Slave Address is 2 types, it is determined by ADDR Terminal
ADDR = ‘H’ ( ADDR ≧0.7VCC ) → “1011100“
ADDR = 'L' ( ADDR ≦0.3VCC ) → “0100011“
3 ) Write Format
BH1715FVC is not able to accept plural command without stop condition. Please insert SP every 1 Opecode.
ST Slave Address R/W
0 Ack Opecode Ack SP
4 ) Read Format
ST Slave Address R/W
1 Ack High Byte [15:8] 215 214 213 212 211 210 29 28Ack
Low Byte [7:0]
27 26 25 24 23 22 21 20Ack SP
ex )
High Byte = "1000_0011"
Low Byte = "1001_0000"
( 215 + 29 + 28 + 27 + 24 ) / 1.2 ≒ 28067 [ lx ] ※2
* I2C BUS is trademark of Phillips Semiconductors. Please refer formality specification.
from Master to Slave from Slave to Master
tHD ; DAT
S
SDA
SCL
S
tHD ; STA
tLOW
tftr
Sr
tSU ; STA
tSU
;
DAT tf
tSU;STO
tBUF
S
P
tr
S
tHIGH
tHD ; STA
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