WM8255 PDF даташит
Спецификация WM8255 изготовлена «Wolfson» и имеет функцию, называемую «Single Channel 16-bit CIS/CCD AFE». |
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Детали детали
Номер произв | WM8255 |
Описание | Single Channel 16-bit CIS/CCD AFE |
Производители | Wolfson |
логотип |
30 Pages
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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
No Preview Available ! |
Production Data
WM8255
TABLE OF CONTENTS
DESCRIPTION....................................................................................................... 1
FEATURES ............................................................................................................ 1
APPLICATIONS..................................................................................................... 1
BLOCK DIAGRAM ................................................................................................ 1
TABLE OF CONTENTS......................................................................................... 2
PIN CONFIGURATION .......................................................................................... 4
ORDERING INFORMATION.................................................................................. 4
PIN DESCRIPTION................................................................................................ 5
ABSOLUTE MAXIMUM RATINGS ........................................................................ 6
RECOMMENDED OPERATING CONDITIONS..................................................... 6
THERMAL PERFORMANCE................................................................................. 6
ELECTRICAL CHARACTERISTICS ..................................................................... 7
INPUT VIDEO SAMPLING ............................................................................................. 10
OUTPUT DATA TIMING................................................................................................. 10
SERIAL INTERFACE ..................................................................................................... 11
PWM TIMING ................................................................................................................. 12
DEVICE DESCRIPTION ...................................................................................... 13
INTRODUCTION ............................................................................................................ 13
INPUT SAMPLING ......................................................................................................... 13
RESET LEVEL CLAMPING (RLC) ................................................................................. 13
CDS/NON-CDS PROCESSING ..................................................................................... 14
OFFSET ADJUST AND PROGRAMMABLE GAIN ........................................................ 15
ADC INPUT BLACK LEVEL ADJUST ............................................................................ 16
OVERALL SIGNAL FLOW SUMMARY .......................................................................... 16
CALCULATING OUTPUT FOR ANY GIVEN INPUT...................................................... 16
OUTPUT FORMATS ...................................................................................................... 18
LED CURRENT DRIVE CONTROL ............................................................................... 19
LED CURRENT DRIVE SEQUENCE SYNCHRONISATION AND PROGRESSION..... 20
LED CURRENT DRIVE INTENSITY CONTROL............................................................ 21
LED CURRENT DRIVE CURRENT PWM CONTROL .................................................. 25
LED CURRENT DRIVE CURRENT BLANKING PERIOD ............................................. 26
CURRENT ACCURACY AND ABSOLUTE MAXIMUM CURRENT LIMIT ..................... 30
LED CONTROL WORKED EXAMPLE........................................................................... 32
CONTROL INTERFACE................................................................................................. 34
TIMING REQUIREMENTS ............................................................................................. 34
PROGRAMMABLE VSMP DETECT CIRCUIT............................................................... 35
REFERENCES............................................................................................................... 36
POWER SUPPLY........................................................................................................... 36
POWER MANAGEMENT ............................................................................................... 36
POWER ON SEQUENCE .............................................................................................. 37
OPERATING MODES .................................................................................................... 37
OPERATING MODE TIMING DIAGRAMS..................................................................... 38
DEVICE REVISION CODES .......................................................................................... 39
DEVICE CONFIGURATION................................................................................. 40
REGISTER MAP .................................................................................................. 40
EXTENDED PAGE REGISTERS ................................................................................... 41
REGISTER MAP DESCRIPTION................................................................................... 41
EXTENDED PAGE REGISTER MAP DESCRIPTION ................................................... 45
RECOMMENDED EXTERNAL COMPONENTS.................................................. 46
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PD, Rev 4.7, August 2013
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WM8255
Production Data
PACKAGE DIMENSIONS.................................................................................... 47
QFN 5 X 5 X 0.85MM ..................................................................................................... 47
QFN 4 X 4 X 0.85MM ..................................................................................................... 47
IMPORTANT NOTICE ......................................................................................... 48
ADDRESS: ..................................................................................................................... 48
REVISION HISTORY ........................................................................................... 49
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PD, Rev 4.7, August 2013
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