WM8181

12-bit 2MSPS Serial Output CIS/CCD Digitiser

Advanced Information, January 2000, Rev 3.0

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

.

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 1

µA.

The WM8181 is available in a 16-pin wide-body SOIC

package.

FEATURES

•

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

•

USB bus powered scanners

•

Flatbed scanners

•

Sheetfeed scanners

•

Contact image sensors (CIS)

•

Linear CCDs

BLOCK DIAGRAM

CLAMP (11)

VREFIN (3)

VINM (5)

VINP (4)

0.8*VDD

(1)

AGND1

1.5V

BAND-

GAP

HOLD

SAMPLE/

(7)

VRT

GENERATOR

VRT/VRB

PD

(2)

AGND2

(6)

VRB

12

TIMING AND

POWER DOWN CONTROL

PARALLEL

TO

SERIAL

(10) DGND

(14) DOUT

VSMP

(12)

MCLK

(13)

(15) DVDD

-

+

x1

AVDD

(16)

WM8181

ADC