ROHM BH1751FVI Technical data

Ambient Light Sensor IC Series

Digital 16bit Serial Output Type
Ambient Light Sensor IC

BH1751FVI

●Descriptions

BH1751FVI is an digital Ambient Light Sensor IC for I
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. 0.11 lx, max. 100000 lx by using this function. )

12) Small measurement variation (+/- 20%)

13) The influence of infrared is very small.

14) Build in power on reset circuit

●Applications

Mobile phone, LCD TV, NOTE PC, Portable game machine, Digital camera, Digital video camera, PDA, LCD display

●Absolute Maximum Ratings

2

C bus interface. This IC is the most suitable to obtain the ambient light

No.11046EBT09

Parameter Symbol Ratings Units

Supply Voltage Vmax

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

VCC Voltage Vcc 2.4 3.0 3.6 V

I2C Reference Voltage VDVI 1.65 - VCC V

Min. Typ. Max.

4.5 V

Ratings

Units

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© 2011 ROHM Co., Ltd. All rights reserved.

1/16

2011.11 - Rev.B

BH1751FVI

● Electrical Characteristics ( VCC = 3.0V, DVI = 3.0V, Ta = 25℃, unless otherwise noted )

Parameter Symbol

Min. Typ. Max.

Limits

Units Conditions

Supply Current Icc1 － 120 190 µA Ev = 100 lx

Powerdown Current Icc2 － 0.85 1.5 µA No input Light

Peak Wave Length λp － 560 － nm

Technical Note

1

※

Measurement Accuracy S/A 0.96 1.2 1.44 times

Dark ( 0 lx ) Sensor out S0 0 0 3 count H-Resolution Mode

Sensor out / Actual lx
EV = 1000 lx

※

1, ※2

※

H-Resolution Mode Resolution rHR － 1 － lx

L-Resolution Mode Resolution rLR － 4 － lx

H-Resolution Mode
Measurement Time

L-Resolution Mode
Measurement Time

Incandescent /
Fluorescent Sensor out ratio

tHR － 120 180 ms

t

LR － 16 24 ms

F － 1 － times

rI

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

3

SCL, SDA Input ‘L’ Voltage 2 VIL2 － － DVI – 1.26 V 1.65V ≦ DVI ＜ 1.8V

SCL, SDA, ADDR Input ‘H’ Current IIH

SCL, SDA, ADDR Input ‘L’ Current IIL

I2C SCL Clock Frequency fSCL

I2C Bus Free Time tBUF 1.3

I2C Hold Time ( repeated )
START Condition

I2C Set up time
for a Repeated START Condition
I2C Set up time
for a Repeated STOP Condition

t

HDSTA 0.6

SUSTA 0.6

t

t

SUSTD 0.6

I2C Data Hold Time tHDDAT 0

I2C Data Setup Time tSUDAT 100

I2C ‘L’ Period of the SCL Clock tLOW 1.3

I2C ‘H’ Period of the SCL Clock tHIGH 0.6

I2C SDA Output ‘L’ Voltage VOL 0

※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 or H-resolution mode2 if dark data ( less than 10 lx ) is need.

－ －

－ －

－ －

－

－

－

－

－

－

－

－

－

10 µA

10 µA

400 kHz

－ µs

－ µs

－ µs

－ µs

0.9 µs

－ ns

－ µs

－ µs

0.4 V IOL = 3 mA

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© 2011 ROHM Co., Ltd. All rights reserved.

2/16

2011.11 - Rev.B

BH1751FVI

●Reference Data

1.2

1

0.8

0.6

Ratio

0.4

0.2

0

400 500 600 700 800 900 1000 1100

Fig.1 Spectral Response

1.2

1

0.8

0.6

Ratio

0.4

0.2

Wavelength [ nm ]

1pin

-

-

+

+

0

-90 -60 -30 0 30 60 90

Angle [ deg ]

Fig.4 Directional Characteristics 1

1.2

1

0.8

0.6

Ratio

0.4

0.2

0

-40-200 20406080100

Fig.7 Measurement Accuracy

Temperature Dependency

10

Ta [ ℃ ]

1

ICC @ POWER DOWN [ uA ]

0.1

-40-20 0 20406080100

Fig.10 V

Ta [ ℃ ]

CC – ICC@0 Lx

( POWER DOWN )

64

56

48

40

32

H-Res.

24

Measurement Result

16

8

0

0 8 16 24 32 40 48 56 64

Illuminance [ lx ]

Fig.2 Illuminance -

Measuremnet Result 1

1.2

1

0.8

0.6

Ratio

0.4

0.2

0

-90 -60 -30 0 30 60 90

Angle [ deg ]

L-Res.

-

1pin

-

+

+

Fig.5 Directional Characteristics 2

Fluorescent

Light

Incandescent

Light

Halogen

Light

Kripton Light

Artifical Sun

Light

White LED

00.511.52

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

22.533.54

DVI=1.8V

VCC [ V ]

Fig.11 Measurement Result

CC Dependency

V

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

蛍光灯白熱灯感度比

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 V

VCC=3V

DVI [ V ]

CC - ICC

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3/16

2011.11 - Rev.B

BH1751FVI

●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

・POR

●Measurement Procedure

State is automatically changed to
Power Down mode.

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 "0100_0101".

Internal Oscillator ( typ. 320kHz ). It is CLK for internal logic.

Power on reset. All register is reset after VCC is supplied. Please refer P.8 (Caution of power on reset function).

One Time Measurement

PD

AMP

Power supply

Power Down

Power On

Measurement Command

ADC

VCC

OSC

GND

Initial state is Power Down mode after
VCC and DVI supply.

DVI

Logic

+

I2C Interface

POR

ADDR

Continuous Measurement

State Transition by I2C write-command.

Automatically State Transition

* "Power On" Command is possible to omit.

Technical Note

SCL

SDA

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4/16

2011.11 - Rev.B

BH1751FVI

●Instruction Set Architecture

Instruction Opecode Comments

Power Down 0000_0000 No active state.

Power On 0000_0001 Waiting for measurement command.

Technical Note

Reset 0000_0111

Continuously H-Resolution Mode 0001_0000

Continuously H-Resolution Mode2 0001_0001

Continuously L-Resolution Mode 0001_0011

One Time H-Resolution Mode 0010_0000

One Time H-Resolution Mode2 0010_0001

One Time L-Resolution Mode 0010_0011

Change Measurement time
( High bit )

Change Masurement time
( Low bit )

※ Don't input the other opecode.

●Measurement mode explanation

Measurement Mode Measurement Time. Resolurtion

H-resolution Mode2 Typ. 120ms. 0.5 lx

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 )
H-resolution mode2 is also suitable to detect for darkness.

●Explanation of Asynchronous reset and Reset command "0000_0111"

1) Asynchronous reset
All registers are reset and BH1751FVI becomes power down during DVI = 'L'. Initial reset is not necessary, because power
on reset function is included in this product.

2) Reset command
Reset command is for only reset Illuminance data register. ( reset value is '0' )It is not necessary after power supply to
VCC because power on reset function is included in this product.
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.

01000_MT[7,6,5]

011_MT[4,3,2,1,0]

Reset Data register value. Reset command is not acceptable in
Power Down mode.

Start measurement at 1lx resolution.
Measurement Time is typically 120ms.

Start measurement at 0.5lx resolution.
Measurement Time is typically 120ms.

Start measurement at 4lx resolution.
Measurement Time is typically 16ms.

Start measurement at 1lx resolution.
Measurement Time is typically 120ms.
It is automatically set to Power Down mode after measurement.

Start measurement at 0.5lx resolution.
Measurement Time is typically 120ms.
It is automatically set to Power Down mode after measurement.

Start measurement at 4lx resolution.
Measurement Time is typically 16ms.
It is automatically set to Power Down mode after measurement.

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."

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5/16

2011.11 - Rev.B

BH1751FVI

●Timing chart for VCC and DVI power supply sequence

DVI is I2C bus reference voltage terminal. And it is also asynchronous reset terminal. In DVI 'L' term, internal state is set to
Power Down mode.Initial reset is not necessary, because power on reset function is included in this product. DVI supply with
VCC supply, or after VCC supply. Please do not become DVI＞VCC.

1) Recommended Timing chart1 for VCC and DVI supply.

VCC

DVI

2) Recommended Timing chart2 for VCC and DVI supply.

( If DVI can not supply with VCC supply )

VCC

DVI

Technical Note

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6/16

2011.11 - Rev.B