TCS3404, TCS3414

DIGITAL COLOR SENSORS

TAOS137A − APRIL 2011

19

The LUMENOLOGY

r Company

r

r

Copyright

E 2011, TAOS Inc.

www.taosinc.com

Gain Register (07h)

The Gain register provides a common gain control adjustment for all four parallel ADC output channels. Two

gain bits [5:4] in the Gain Register allow the relative gain to be adjusted from 1

advantage of the gain adjust is to extend the dynamic range of the light input up to a factor of 64

or digital saturation occurs. If analog saturation has occurred, lowering the gain sensitivity will likely prevent

analog saturation especially when the integration time is relatively short. For longer integration times, the 16-bit

output could be in digital saturation (64K). If lowering the gain to 1

occurring, the use of PRESCALER can be useful.

The PRESCALER is 3 bits [2:0] in the gain register that divides down the output count (i.e. shifts the LSB of the

count value to the right). The PRESCALER adjustment range is divide by 1 to 64 in multiples of 2.

The most sensitive gain setting of the device would be when GAIN is set to 11b (64

to 000b (divide by 1). The least sensitive part setting would be GAIN 00 (1

64). If the part continues to be in digital saturation at the least sensitive setting, the integration time can be

lowered (see Timing Register section).

Table 9. Gain Register

6

75

4

2

31

0

0

00

0

0

00

0

Reset Value:

GAIN

Resv

GAIN

Resv

07h

PRESCALER

Resv

FIELD

BITS

DESCRIPTION

Resv

7:6

Reserved. Write as 0.

Analog Gain Control. This field switches the common analog gain of the four ADC channels. Four gain

modes are provided:

FIELD VALUE

GAIN

GAIN

5:4

00

1

×

GAIN

5:4

01

4

×

10

16

×

11

64

×

Resv

3

Reserved. Write as 0.

Prescaler. This field controls a 6-bit digital prescaler and divider. The prescaler reduces the sensitivity

of each ADC integrator as shown in the table below:

FIELD VALUE

PRESCALER MODE

000

Divide by 1.

001

Divide by 2.

PRESCALER

2:0

010

Divide by 4.

PRESCALER

2:0

011

Divide by 8.

100

Divide by 16.

101

Divide by 32.

110

Divide by 64.

111

Not used.