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DESCRIPTION
The WM8259 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 3MSPS.
The device has two selectable video input pins and one
complete analogue signal processing channel containing
Reset Level Clamping, Correlated Double Sampling,
Programmable Gain and Offset adjust functions. Internal
multiplexers allow fast switching of offset and gain for line-
by-line colour processing. The output from this channel is
time multiplexed into a high-speed 16-bit Analogue to Digital
Converter. The digital output data is available in 4-bit wide
multiplexed format.
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.
The device uses an analogue supply voltage of 3.3V and a
digital interface supply of between 2.5V and 3.3V. The
WM8259 typically only consumes 132mW when operating
from a single 3.3V supply.
WM8259
Single Channel 16-bit CIS/CCD AFE with 4-bit Wide Output
FEATURES
•
•
•
•
•
•
•
•
•
•
•
•
•
16-bit ADC
3MSPS conversion rate
Low power - 132mW typical
3.3V single supply or 3.3V/2.5V dual supply operation
Single channel operation, selectable inputs
Correlated double sampling
Programmable gain (8-bit resolution)
Programmable offset adjust (8-bit resolution)
Programmable clamp voltage
4-bit wide multiplexed data output format
Internally generated voltage references
20-lead SSOP package
Serial control interface
APPLICATIONS
•
•
•
•
Flatbed and sheetfeed scanners
USB compatible scanners
Multi-function peripherals
High-performance CCD sensor interface
BLOCK DIAGRAM
WOLFSON MICROELECTRONICS plc
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Production Data, April 2007, Rev 4.2
Copyright
©2007
Wolfson Microelectronics plc
WM8259
TABLE OF CONTENTS
Production Data
DESCRIPTION .......................................................................................................1
FEATURES.............................................................................................................1
APPLICATIONS .....................................................................................................1
BLOCK DIAGRAM .................................................................................................1
PIN CONFIGURATION...........................................................................................3
ORDERING INFORMATION ..................................................................................3
PIN DESCRIPTION ................................................................................................4
ABSOLUTE MAXIMUM RATINGS.........................................................................5
RECOMMENDED OPERATING CONDITIONS .....................................................5
ELECTRICAL CHARACTERISTICS ......................................................................6
INPUT VIDEO SAMPLING .....................................................................................8
OUTPUT DATA TIMING.........................................................................................9
SERIAL INTERFACE..............................................................................................9
DEVICE DESCRIPTION.......................................................................................10
INTRODUCTION ..................................................................................................10
INPUT SAMPLING ...............................................................................................10
RESET LEVEL CLAMPING (RLC) .......................................................................10
CDS/NON-CDS PROCESSING............................................................................11
OFFSET ADJUST AND PROGRAMMABLE GAIN...............................................12
ADC INPUT BLACK LEVEL ADJUST...................................................................13
OVERALL SIGNAL FLOW SUMMARY ................................................................13
CALCULATING OUTPUT FOR ANY GIVEN INPUT ............................................13
OUTPUT DATA FORMAT ....................................................................................14
CONTROL INTERFACE.......................................................................................15
TIMING REQUIREMENTS ...................................................................................15
PROGRAMMABLE VSMP DETECT CIRCUIT .....................................................16
REFERENCES .....................................................................................................17
POWER SUPPLY.................................................................................................17
POWER MANAGEMENT .....................................................................................17
OPERATING MODES ..........................................................................................17
OPERATING MODE TIMING DIAGRAMS ...........................................................18
DEVICE CONFIGURATION .................................................................................20
REGISTER MAP...................................................................................................20
REGISTER MAP DESCRIPTION .........................................................................21
RECOMMENDED EXTERNAL COMPONENTS ..................................................24
PACKAGE DIMENSIONS ....................................................................................25
IMPORTANT NOTICE ..........................................................................................26
ADDRESS: ...........................................................................................................26
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PD Rev 4.2 April 2007
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WM8259
PIN CONFIGURATION
AGND2
DVDD1
VSMP
MCLK
DGND
SEN
DVDD2
SDI
SCK
OP[0]
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
VINP1
VINP2
VRLC/VBIAS
VRT
VRB
AGND1
AVDD
OP[3]/SDO
OP[2]
OP[1]
Production Data
WM8259
ORDERING INFORMATION
ORDER CODE
WM8259SCDS/V
WM8259SCDS/RV
TEMPERATURE
RANGE
0 to 70
o
C
0 to 70
o
C
PACKAGE
20-lead SSOP
(Pb-free, drybagged)
20-lead SSOP
(Pb-free, drybagged, tape
and reel)
MOISTURE
PEAK SOLDERING
SENSITIVITY LEVEL
TEMPERATURE
MSL3
MSL3
260
o
C
260
o
C
Note:
Reel quantity = 2,000
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PD Rev 4.2 April 2007
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WM8259
PIN DESCRIPTION
PIN #
1
2
3
4
5
6
7
8
9
NAME
AGND2
DVDD1
VSMP
MCLK
DGND
SEN
DVDD2
SDI
SCK
TYPE
Supply
Supply
Digital input
Digital input
Supply
Digital input
Supply
Digital input
Digital input
DESCRIPTION
Analogue ground pin (0V)
Digital Core supply (3.3V)
Video sample synchronisation pulse.
Production Data
Master clock. This clock is applied at N times the input pixel rate (N = 2, 3, 6, 8 or
any multiple of 2 thereafter depending on input sample mode).
Digital ground (0V).
Enables the serial interface when high.
Digital I/O supply (2.5V-3.3V), all digital I/O pins.
Serial data input.
Serial clock.
Digital multiplexed output data bus.
ADC output data (d15:d0) is available in 4-bit multiplexed format as shown below.
A
B
d8
d9
d10
d11
C
d4
d5
d6
d7
D
d0
d1
d2
d3
10
11
12
13
OP[0]
OP[1]
OP[2]
OP[3]/SDO
Digital output
Digital output
Digital output
Digital output
d12
d13
d14
d15
Alternatively, pin OP[3]/SDO may be used to output register read-back data when
address bit 4=1 and SEN has been pulsed high. See Serial Interface description in
Device Description section for further details.
14
15
16
17
18
AVDD
AGND1
VRB
VRT
VRLC/VBIAS
Supply
Supply
Analogue output
Analogue output
Analogue I/O
Analogue supply (3.3V)
Analogue ground (0V).
Lower reference voltage.
This pin must be connected to AGND via a decoupling capacitor.
Upper reference voltage.
This pin must be connected to AGND via a decoupling capacitor.
Selectable analogue output voltage for RLC or single-ended bias reference.
This pin would typically be connected to AGND via a decoupling capacitor.
VRLC can be externally driven if programmed Hi-Z.
Video input2 for analog switch
Video input1.
19
20
VINP2
VINP1
Analogue input
Analogue input
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PD Rev 4.2 April 2007
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WM8259
ABSOLUTE MAXIMUM RATINGS
Production Data
Absolute Maximum Ratings are stress ratings only. Permanent damage to the device may be caused by continuously operating at
or beyond these limits. Device functional operating limits and guaranteed performance specifications are given under Electrical
Characteristics at the test conditions specified.
ESD Sensitive Device. This device is manufactured on a CMOS process. It is therefore generically susceptible
to damage from excessive static voltages. Proper ESD precautions must be taken during handling and storage
of this device.
Wolfson tests its package types according to IPC/JEDEC J-STD-020B for Moisture Sensitivity to determine acceptable storage
conditions prior to surface mount assembly. These levels are:
MSL1 = unlimited floor life at <30°C / 85% Relative Humidity. Not normally stored in moisture barrier bag.
MSL2 = out of bag storage for 1 year at <30°C / 60% Relative Humidity. Supplied in moisture barrier bag.
MSL3 = out of bag storage for 168 hours at <30°C / 60% Relative Humidity. Supplied in moisture barrier bag.
The Moisture Sensitivity Level for each package type is specified in Ordering Information.
CONDITION
Analogue supply voltage: AVDD
Digital core supply voltage: DVDD1
Digital IO supply voltage: DVDD2
Digital ground: DGND
Analogue grounds AGND
Digital inputs, digital outputs and digital I/O pins
Analogue inputs (VINP1, VINP2)
Other pins
Operating temperature range: T
A
Notes:
1.
2.
3.
GND denotes the voltage of any ground pin.
AGND and DGND pins are intended to be operated at the same potential. Differential voltages between these pins
will degrade performance.
AVDD and DVDD1 pins are intended to be operated at the same potential. Differential voltages between these pins
will degrade performance.
MIN
GND - 0.3V
GND - 0.3V
GND - 0.3V
GND - 0.3V
GND - 0.3V
GND - 0.3V
GND - 0.3V
GND - 0.3V
0
°
C
MAX
GND + 4.2V
GND + 4.2V
GND + 4.2V
GND + 0.3V
GND + 0.3V
DVDD + 0.3V
AVDD + 0.3V
AVDD + 0.3V
+70
°
C
RECOMMENDED OPERATING CONDITIONS
CONDITION
Operating temperature range
Analogue supply voltage
Digital Core supply voltage
Digital I/O supply voltage
SYMBOL
T
A
AVDD
DVDD1
DVDD2
MIN
0
2.97
2.97
2.5
3.3
3.3
3.3
TYP
MAX
70
3.63
3.63
3.63
UNITS
°C
V
V
V
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PD Rev 4.2 April 2007
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