SFH7773 datasheet(3/23 Pages) OSRAM

3 / 23 page

December 12, 2011

page 3 of 23

4.2 Directivity of the ALS

Fig. 5 presents the directivity of the ALS.

This is an important point for considering the

design of a potential cover glass (please

refer to Sec. 10.1 for more details).

4.3 Sensitivity Range of the ALS

The range of the ALS can be programmed

by the user via the ALS integration time

(register 0x26). Per default (integration time

= 100 ms) the range covers 0.3 lx to 6.5 klx

with a resolution of typ. 0.1 lx/count. A

doubling of the integration time changes the

sensitivity range by a factor of two. Please

400 500 600 700 800 900 1000 1100

0,0

0,2

0,4

0,6

0,8

1,0

Wavelength / nm

Si-Photodetector

V-lambda

SFH 7773

Fig. 3: Spectral sensitivity of the SFH 7773

vs. the human eye (V-lambda) and standard

Si-photodetectors.

100

Human Eye Level

Flourescent

Lamp

Halogen

Lamp

Sunlight

Light

Bulb

Standard

Light A

(2856 K)

Fig. 4: Ambient light sensor accuracy vs.

different light sources. Normalized to 100 lux

and standard light A.

tint

ALS

Range

ALS

Resolution

10 ms

3.0 lx - 65535 lx

1.00 lx/count

20 ms

1.5 lx - 32767 lx

0.50 lx/count

50 ms

0.60 lx - 13106 lx 0.20 lx/count

100 ms

0.30 lx - 6553 lx

0.10 lx/count

200 ms

0.15 lx - 3277 lx

0.05 lx/count

500 ms

0.06 lx - 1311 lx

0.02 lx/count

1000 ms 0.03 lx - 655 lx

0.01 lx/count

Tab. 2: ALS integration time settings tint and

their relation to ALS range and resolution

(default: tint = 100 ms).

-90

-60

-30

100

45°

30°

Angle / °

Short Axis

Long Axis

ALS

Directional Sensitivity of the Ambient Light Sensor

40°

Fig. 5: Directional characteristics of the

ambient light sensor.

100

1000 10000 100000

0.1

100

1000

10000

Illumination / Lux

Ambient Light Sensor Count vs. Illumination

(Standard Light A)

Fig. 6: Ambient light sensor count vs.

illumination (integration time = 100 ms).

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