WM8198
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(8 + 8) Bit Output 16-bit CIS/CCD AFE/Digitiser
DESCRIPTION
FEATURES
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16-bit ADC
The WM8198 is a 16-bit analogue front end/digitiser IC
which processes and digitises the analogue output signals
from CCD sensors or Contact Image Sensors (CIS) at pixel
sample rates of up to 6MSPS.
6MSPS conversion rate
Low power – 212mW typical
5V single supply or 5V/3.3V dual supply operation
Single or 3 channel operation
The device includes three analogue signal processing
channels each of which contains Reset Level Clamping,
Correlated Double Sampling and Programmable Gain and
Offset adjust functions. Three multiplexers allow single
channel processing. The output from each of these
channels is time multiplexed into a single high-speed 16-bit
Analogue to Digital Converter. The digital output data is
available in 8 or 4-bit wide multiplexed format.
Correlated double sampling
Dual Range Programmable Gain Amplifier (9-bit resolution)
Programmable offset adjust (8-bit resolution)
Programmable clamp voltage
8 or 4-bit wide multiplexed data output formats
Internally generated voltage references
28-pin SSOP package
An internal 4-bit DAC is supplied for internal reference level
generation. This may be used during CDS to reference CIS
signals or during Reset Level Clamping to clamp CCD
signals. An external reference level may also be supplied.
ADC references are generated internally, ensuring optimum
performance from the device.
Serial control interface
APPLICATIONS
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Flatbed and sheetfeed scanners
USB compatible scanners
Using an analogue supply voltage of 5V and a digital
interface supply of either 5V or 3.3V, the WM8198 typically
only consumes 195mW when operating from a single
5V supply.
Multi-function peripherals
High-performance CCD sensor interface
BLOCK DIAGRAM
VRLC/VBIAS
VSMP MCLK
AVDD DVDD1 DVDD2
VRT VRX VRB
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CL
RS VS
TIMING CONTROL
WM8198
VREF/BIAS
R
8
M
U
X
OFFSET
DAC
OEB
G
B
RINP
RLC
RLC
CDS
CDS
+
+
PGA
9
+
+
M
U
X
I/P SIGNAL
POLARITY
ADJUST
R
G
B
OP[0]
OP[1]
M
U
X
OP[2]
OP[3]
OP[4]
OP[5]
DATA
I/O
PORT
M
U
X
GINP
BINP
PGA
9
ADC
8
OP[6]
OFFSET
DAC
I/P SIGNAL
POLARITY
ADJUST
OP[7]/SDO
RLC
CDS
PGA
9
+
+
8
OFFSET
DAC
I/P SIGNAL
POLARITY
ADJUST
SEN
SCK
CONFIGURABLE
SERIAL
CONTROL
INTERFACE
SDI
RLC/ACYC
RLC
DAC
4
DGND
AGND1
AGND2
WOLFSON MICROELECTRONICS plc
Production Data, June 2004, Rev 4.0
Copyright 2002 Wolfson Microelectronics plc
w :: www.wolfsonmicro.com