ht82v24 Holtek Semiconductor Inc., ht82v24 Datasheet - Page 9

• Manufacturer Part Number: ht82v24
• Description: Ht82v24 -- 16-bit, 15msps, 3-channel Ccd/cis Analog Signal Processor
• Manufacturer: Holtek Semiconductor Inc.

PGA Gain Registers
There are three PGA registers for use in individually pro-
gramming the gain in the red, green and blue channels.
Bits D8, D7 and D6 in each register must be set low, and
bits D5 through D0 control the gain range in 64 incre-
ments. See figure for a graph of the PGA gain versus
PGA register code. The coding for the PGA registers is a
straight binary, with an all zero words corresponding to
the minimum gain setting (1x) and an all one word corre-
sponding to the maximum gain setting (6x).
The HT82V24 uses one Programmable Gain Amplifier
(PGA) for each channel. Each PGA has a gain range
from 1x (0dB) to 6x (15.6dB), adjustable in 64 steps.
The Figure shows the PGA gain as a function of the PGA
register code. Although the gain curve is approximately
linear in dB, the gain in V/V varies in nonlinear propor-
tion with the register code, according to the following the
equation: Gain=
Note: * Power-on default value
Offset Registers
There are three offset registers for use in individually programming the offset in the red, green, and blue channels. Bits
D8 through D0 control the offset range from 300mV to 300mV in 512 increments.
The coding for the offset registers is sign magnitude, with D8 as the sign bit. The following table shows the offset range
as a function of the bits D8 through D0.
Note: * Power-on default value
Rev. 1.00
Set to 0
MSB
D8
D8
0
0
0
0
0
0
0
1
1
1
Set to 0
D7
0
0
0
0
1 4.85x(
D7
0
0
1
0
0
1
+
Set to 0
6
D6
0
0
0
0
63 G
D6
63
0
0
1
0
0
1
-
)
MSB
D5
0
0
1
1
D5
0
0
1
0
0
1
PGA Gain Register Settings
D4
0
0
1
1
D4
0
0
1
0
0
1
D3
0
0
1
1
9
.
.
.
Where G is the decimal value of the gain register con-
tents, and varies from 0 to 63.
D3
0
0
1
0
0
1
.
.
.
.
.
.
D2
0
0
1
1
PGA Gain Transfer Function
D2
0
0
1
0
0
1
D1
0
0
1
1
D1
0
0
1
0
0
1
LSB
D0
0*
1
0
1
LSB
September 7, 2005
D0
1.039
(V/V)
0*
Gain
5.57
1
1
0
1
1
1.0
6
.
.
.
HT82V24
Gain (dB)
Offset
(mV)
1.17
300
0.33
14.9
15.6
1.17
300
0.0
0
0
.
.
.
.
.
.
.
.
.