TCS3404, TCS3414
DIGITAL COLOR SENSORS
TAOS137A − APRIL 2011
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× to 64× in 4× increments. The
advantage of the gain adjust is to extend the dynamic range of the light input up to a factor of 64× before analog
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× does not prevent digital saturation from
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×), and PRESCALER is set
to 000b (divide by 1). The least sensitive part setting would be GAIN 00 (1×) and PRESCALER 110 (divide by
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
7
Resv
0
6
Resv
0
5
0
4
0
3
Resv
0
2
1
0
0
GAIN
07h
GAIN
PRESCALER
0
Reset Value:
0
FIELD
BITS
DESCRIPTION
Resv
7:6
5:4
3
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
00
1×
4×
16×
64×
GAIN
Resv
01
10
11
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
001
010
011
100
101
110
111
Divide by 1.
Divide by 2.
Divide by 4.
Divide by 8.
Divide by 16.
Divide by 32.
Divide by 64.
Not used.
PRESCALER
2:0
Copyright E 2011, TAOS Inc.
The LUMENOLOGY r Company
r
r
www.taosinc.com
19
TAOS [ TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS ]
