WM8181
12-bit 2MSPS Serial Output CIS/CCD Digitiser
Advanced Information, January 2000, Rev 3.0
DESCRIPTION
The WM8181 is a 12-bit resolution, 2MSPS single channel
image digitiser which is designed for easy interface to either
CIS or CCD linear image sensors. Data is output in serial
mode. The applied clock frequency (MCLK) equals the bit
rate of the data output. The sample rate of the WM8181 can
be either 1/12th or 1/16th of the applied master clock
frequency.
The device can be configured for either single-ended or
differential input operation. In single ended input mode, a
reset clamp voltage can be applied to the analogue signal,
under the control of a digital signal at the CLAMP pin. The
WM8181 will accept either positive or negative-going video
signals at any voltage between AGND and AVDD. The ADC
references are internally generated. The range of these
references may be derived internally using a bandgap
generator or externally using the VREFIN pin.
The WM8181 is powered from either 3.3V or 5V single
supplies. The device may also be powered from split 5V
and 3.3V dual supplies. Typically, the WM8181 consumes
23mA supply current in normal operation. When the device
is powered down, the supply current falls to less than 1µA.
The WM8181 is available in a 16-pin wide-body SOIC
package.
FEATURES
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12-bit 2MSPS ADC
No missing codes
Serial output
Simple clocking
Internal or external ADC reference range control
Accepts positive or negative video
Rail to rail input range
Reset-level clamp switch
3.3V or 5V single supplies
5V/3.3V dual supplies
23mA supply current
16-pin wide body SOIC package
APPLICATIONS
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USB bus powered scanners
Flatbed scanners
Sheetfeed scanners
Contact image sensors (CIS)
Linear CCDs
BLOCK DIAGRAM
AVDD
(16)
VSMP
(12)
MCLK
(13)
PD
TIMING AND
POWER DOWN CONTROL
WM8181
(15) DVDD
VINP (4)
SAMPLE/
HOLD
VINM (5)
(10) DGND
CLAMP (11)
0.8*VDD
VREFIN (3)
+
-
x1
VRT/VRB
ADC
12
PARALLEL
TO
SERIAL
(14) DOUT
1.5V
BAND-
GAP
GENERATOR
(1)
(2)
AGND1 AGND2
(7)
VRT
(6)
VRB
WOLFSON MICROELECTRONICS LTD
Lutton Court, Bernard Terrace, Edinburgh, EH8 9NX, UK
Tel: +44 (0) 131 667 9386
Fax: +44 (0) 131 667 5176
Email: sales@wolfson.co.uk
http://www.wolfson.co.uk
Advanced Information
data sheets contain
preliminary data on new products in the
preproduction phase of development.
Supplementary data will be published at a
later date.
2000
Wolfson Microelectronics Ltd
.
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
