Functional description

VM6101

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2.1

Light measurement channels

The VM6101 has four independent wide dynamic range photosensors and current-to-

frequency converters. Each channel produces a digital output with a frequency proportional

to the incoming light level on the photosensor. By construction, the device ensures

automatic exposure control.

Figure 2.

Light-to-Frequency converter (L2F)

The output period is measured using a 27-bit free-running counter and the internal 3.6 MHz

oscillator clock; counter values are then read through the serial interface.

The typical light response is shown in

Figure 3. below, obtained using a CIE D65 white point

light source (~ daylight illumination) and no light diffuser.

Figure 3.

Light response

1000

10000

100000

1000000

10000000

1

10

100

1000

Lum inance (lx)

Y

R

G

B

1.0E+03

1.0E+04

1.0E+05

1.0E+06

1.0E+07

1

10

100

1000

Illum inance (lx)

Y

R

G

B