WM8255 Datasheet, PDF (1/49 Pages) Cirrus Logic – Single Channel 16-bit CIS/CCD AFE with RGB LED Current Drive

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WM8255
Single Channel 16-bit CIS/CCD AFE with RGB LED Current Drive
DESCRIPTION
The WM8255 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 12 MSPS.
The device includes a complete 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 a 2 bit or 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 includes an RGB LED current drive using current
and PWM functionality to control the operation of sensor
LEDs.
The device typically uses an analogue supply voltage of
5.75V and a digital interface supply of 3.3V.
BLOCK DIAGRAM
FEATURES
 16-bit ADC
 12 MSPS conversion rate
 Low power – 250 mW typical
 5.75V and 3.3V supply operation
 Single channel operation
 Correlated double sampling
 Programmable gain (8-bit resolution)
 Programmable offset adjust (8-bit resolution)
 Programmable clamp voltage
 RGB LED current drive using current and PWM
 2-bit or 4-bit wide multiplexed data output format
 Internally generated voltage references
 28-lead QFN package
 3 wire serial control interface
APPLICATIONS
 Flatbed and sheetfeed scanners
 USB compatible scanners
 Multi-function peripherals
WOLFSON MICROELECTRONICS plc
Production Data, August 2013, Rev 4.7
Copyright 2013 Wolfson Microelectronics plc