WOLFSON WM8224

WM8224
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60MSPS 3-Channel AFE with Multiple Device Operation
and Programmable Automatic Black Level Calibration
DESCRIPTION
FEATURES
The WM8224 is an 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 60MSPS.

12 or 16-bit ADC, 40MSPS conversion rate

8 or 10-bit ADC, 60MSPS conversion rate

Low power – 360 mW typical

3.3V single supply operation
The device includes three analogue signal processing
channels each of which contains Reset Level Clamping,
Correlated Double Sampling and Programmable Gain and
Offset adjust functions. The output from each of these
channels is time multiplexed into a single high-speed 16-bit
Analogue to Digital Converter. The digital data is available in
a variety of output formats via the flexible data port.

3 channel operation

Daisy Chain feature for multiple device use

Correlated double sampling

Programmable gain (9-bit resolution)

Programmable offset adjust (8-bit resolution)

Flexible clamp timing

Programmable clamp voltage

Internally generated voltage references

Automatic Black Level Calibration

32-lead QFN package

Serial control interface
An internal 4-bit DAC is supplied for internal reference level
generation. This may be used during CDS to reference CIS
signals or during Clamping to clamp CCD signals. An
external reference level may also be supplied. ADC
references are generated internally, ensuring optimum
performance from the device.
A programmable automatic Black-Level Calibration function
is available to adjust the DC offset of the output data. A
daisy chain feature allows multiple devices to operate
together using the same control interface and output data
bus.
APPLICATIONS

Digital Copiers

USB2.0 compatible scanners

Multi-function peripherals

High-speed CCD/CIS sensor interface
BLOCK DIAGRAM
WOLFSON MICROELECTRONICS plc
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Production Data, June 2012, Rev 4.1
Copyright 2012 Wolfson Microelectronics plc.
WM8224
Production Data
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 40MHZ OPERATION ....................................................................................................... 7 60MHZ OPERATION ....................................................................................................... 7 GENERAL CHARACTERISTICS ..................................................................................... 9 INPUT VIDEO SAMPLING ............................................................................................ 11 CDS MODE (CDS=1) .................................................................................................... 11 NON-CDS MODE (CDS=0) ........................................................................................... 12 OUTPUT DATA TIMING ................................................................................................ 14 SERIAL INTERFACE..................................................................................................... 15 INTERNAL POWER ON RESET CIRCUIT .......................................................... 16 DEVICE DESCRIPTION ...................................................................................... 18 INTRODUCTION ........................................................................................................... 18 CONFIGURABLE RESOLUTION OF ADC.................................................................... 18 INPUT SAMPLING ........................................................................................................ 18 RESET LEVEL CLAMPING (RLC) ................................................................................ 19 CDS/NON-CDS PROCESSING..................................................................................... 21 OFFSET ADJUST AND PROGRAMMABLE GAIN........................................................ 21 ADC INPUT BLACK LEVEL ADJUST ........................................................................... 22 OVERALL SIGNAL FLOW SUMMARY ......................................................................... 23 CALCULATING THE OUTPUT CODE FOR A GIVEN INPUT ...................................... 24 OUTPUT FORMATS ..................................................................................................... 25 PROGRAMMABLE AUTOMATIC BLACK LEVEL CALIBRATION ................................ 26 INDICATING THE START OF A BLC PROCEDURE .................................................... 27 BLC DURATION CONTROL ......................................................................................... 28 BLC WORKED EXAMPLE: ............................................................................................ 29 BLC SCENARIOS OF OPERATION.............................................................................. 31 REFERENCES .............................................................................................................. 35 POWER MANAGEMENT .............................................................................................. 35 CONTROL INTERFACE ................................................................................................ 35 MULTIPLE DEVICE OPERATION ................................................................................. 36 OPERATING MODES ................................................................................................... 39 16-BIT MODE ................................................................................................................ 39 10-BIT MODE ................................................................................................................ 40 DEVICE CONFIGURATION ................................................................................. 41 REGISTER MAP............................................................................................................ 41 REGISTER MAP DESCRIPTION .................................................................................. 42 APPLICATIONS INFORMATION ........................................................................ 47 RECOMMENDED EXTERNAL COMPONENTS ........................................................... 47 RECOMMENDED EXTERNAL COMPONENT VALUES .............................................. 47 PACKAGE DIMENSIONS .................................................................................... 48 w
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IMPORTANT NOTICE ......................................................................................... 49 ADDRESS: .................................................................................................................... 49 REVISION HISTORY ........................................................................................... 50 w
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PIN CONFIGURATION
ORDERING INFORMATION
DEVICE
TEMPERATURE
RANGE
PACKAGE
MOISTURE
SENSITIVITY
LEVEL
PEAK SOLDERING
TEMPERATURE
32-lead QFN
WM8224CSEFL
o
0 to 70 C
(5x5x0.9mm)
MSL1
260C
MSL1
260C
(Pb-free)
32-lead QFN
WM8224CSEFL/R
o
0 to 70 C
(5x5x0.9mm)
(Pb-free, tape and reel)
Note:
Reel quantity = 3,500
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PIN DESCRIPTION
PIN
NAME
TYPE
DESCRIPTION
1
RSMP
Digital input
Reset sample pulse (when CDS=1) or clamp control.
2
MCLK
Digital input
Master (ADC) clock. This clock determines the ADC conversion rate.
3
DGND
Supply
4
SEN
Digital input
5
DVDD
Supply
6
SDI
Digital input
Serial interface data input.
7
SCK
Digital input
Serial interface clock.
Digital ground.
Enables the serial interface when high.
Digital supply for logic, clock generator and digital input/output pads.
Digital output data bus. ADC output data (d15:d0) is available in a variety of output
formats.
8
OP[0]
Digital output
d0 (LSB)
9
OP[1]
Digital output
d1
10
OP[2]
Digital output
d2
11
OP[3]
Digital output
d3
12
OP[4]
Digital output
d4
13
OP[5]
Digital output
d5
14
OP[6]
Digital output
d6
15
OP[7]
Digital output
d7
16
OP[8]
Digital output
d8
17
OP[9]
Digital output
d9
18
OP[10]
Digital output
d10
19
OP[11]/SDO
Digital output
d11 (MSB)
Alternatively, pin OP[11]/SDO may be used to output register read-back data. See
Serial Interface description in Device Description section for further details.
Supply
Analogue supply. This must be operated at the same potential as DVDD.
AGND1
Supply
Analogue ground.
VRB
Analogue output
Lower reference voltage.
This pin must be connected to AGND via a decoupling capacitor.
23
VRT
Analogue output
Upper reference voltage.
This pin must be connected to AGND via a decoupling capacitor.
24
VRX
Analogue output
Input return bias voltage.
This pin must be connected to AGND via a decoupling capacitor.
25
VRLC/VBIAS
Analogue I/O
26
BINP
Analogue input
27
GINP
Analogue input
Green channel input video.
28
RINP
Analogue input
Red channel input video.
29
AGND2
Supply
30
DSLCT
Digital Tristate
Input
20
AVDD
21
22
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.
Blue channel input video.
Analogue ground.
Sets 2-bit device ID for daisy chain operation:
0 = Device ID is 00
1 = Device ID is 01
Z = Device ID is 10
31
OEB
Digital input
Output Hi-Z control. All digital outputs set to high-impedance state when input pin
OEB=1, if AUTOZ=0.
Note that readback function will override high-impedance on OP11
This pin has an internal 100k pull-down resistor to AGND.
32
VSMP
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Digital input
Video sample pulse.
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ABSOLUTE MAXIMUM RATINGS
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
MIN
MAX
Analogue supply voltage: AVDD
GND - 0.3V
GND + 5V
Digital supply voltage: DVDD
GND - 0.3V
GND + 5V
Digital ground: DGND
GND - 0.3V
GND + 0.3V
Analogue grounds: AGND1  2
GND - 0.3V
GND + 0.3V
Analogue inputs (RINP, GINP, BINP)
GND - 0.3V
AVDD + 0.3V
Other Analogue pins
GND - 0.3V
AVDD + 0.3V
Digital I/O pins
GND – 0.3V
DVDD + 0.3V
0C
Operating temperature range: TA
+70C
30C max / 85% RH max
Storage temperature prior to soldering
-65C
Storage temperature after soldering
+150C
Notes:
1.
GND denotes the voltage of any ground pin.
2.
AGND1, AGND2 and DGND pins are intended to be operated at the same potential. Differential voltages
between these pins will degrade performance.
RECOMMENDED OPERATING CONDITIONS
CONDITION
SYMBOL
MIN
TYP
MAX
UNITS
TA
0
70
C
Analogue supply voltage
AVDD
2.97
3.3
3.63
V
Digital core and I/O supply voltage
DVDD
2.97
3.3
3.63
V
Operating temperature range
THERMAL PERFORMANCE
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Performance
Thermal resistance – junction to
case
RθJC
Thermal resistance – junction to
ambient
RθJA
Tambient = 25°C
10.27
°C/W
29.45
°C/W
Notes:
Figure 3 Figures given are for package mounted on 4-layer FR4 according to JESD51-5 and JESD51-7.
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ELECTRICAL CHARACTERISTICS
40MHZ OPERATION
Test Conditions
AVDD = DVDD = 3.3V, AGND = DGND = 0V, TA = 25C, MCLK = 40MHz unless otherwise stated.
PARAMETER
SYMBOL
TEST
CONDITIONS
MIN
TYP
MAX
UNIT
Overall System Specification (including 16-bit ADC, PGA, Offset and CDS functions)
Max Conversion rate
40
MSPS
Full-scale input voltage range
LOWREFS=0, Max Gain
0.25
Vp-p
(see Note 1)
LOWREFS=0, Min Gain
3.03
Vp-p
Input signal limits (see Note 2)
VIN
LOWREFS=1, Max Gain
0.15
Vp-p
LOWREFS=1, Min Gain
1.82
Vp-p
FOL_EN=0
AGND-0.3
AVDD+0.3
FOL_EN=1, minimum
AGND
V
V
FOL_EN=1, maximum
AGND+1.2
V
RINP, GINP, BINP to AGND
10
pF
Full-scale transition error
Gain = 0dB;
PGA[8:0] = 18(hex)
20
mV
Zero-scale transition error
Gain = 0dB;
PGA[8:0] = 18(hex)
20
mV
Input capacitance
CIN
Differential non-linearity
DNL
16-bit
1.2
LSB
Integral non-linearity (pk-pk/2)
INL
16-bit
56
LSB
Channel to channel gain matching
Output noise
Unity Gain
1.3
%
10.2
LSB rms
(Unused channels grounded)
Programmable Gain Amplifier
Resolution
9
Gain
0.66 
bits
7.34
* PGA [ 8 : 0 ]
511
V/V
Max gain, each channel
GMAX
8
V/V
Min gain, each channel
GMIN
0.66
V/V
Analogue to Digital Converter
Resolution
16
bits
Speed
40
MSPS
Full-scale input range
LOWREFS=0
2
V
(2*(VRT-VRB))
LOWREFS=1
1.2
V
60MHZ OPERATION
Test Conditions
AVDD = DVDD = 3.3V, AGND = DGND = 0V, TA = 25C, MCLK = 60MHz unless otherwise stated.
PARAMETER
SYMBOL
TEST
CONDITIONS
MIN
TYP
MAX
UNIT
Overall System Specification (including 10-bit ADC, PGA, Offset and CDS functions)
Max Conversion rate
60
MSPS
Full-scale input voltage range
LOWREFS=0, Max Gain
0.26
Vp-p
(see Note 1)
LOWREFS=0, Min Gain
3.03
Vp-p
Input signal limits (see Note 2)
Input capacitance
Full-scale transition error
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VIN
CIN
LOWREFS=1, Max Gain
0.16
Vp-p
LOWREFS=1, Min Gain
1.82
Vp-p
FOL_EN=0
AGND-0.3
AVDD+0.3
V
FOL_EN=1, minimum
AGND
FOL_EN=1, maximum
AGND+1.2
V
V
RINP, GINP, BINP to AGND
10
pF
Gain = 0dB;
PGA[8:0] = 18(hex)
20
mV
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Test Conditions
AVDD = DVDD = 3.3V, AGND = DGND = 0V, TA = 25C, MCLK = 60MHz unless otherwise stated.
PARAMETER
SYMBOL
Zero-scale transition error
TEST
CONDITIONS
MIN
TYP
MAX
UNIT
Gain = 0dB;
PGA[8:0] = 18(hex)
20
mV
Differential non-linearity
DNL
10-bit
0.5
LSB
Integral non-linearity (pk-pk/2)
INL
10-bit
7
LSB
Channel to channel gain matching
Output noise
Unity Gain 10-bit
2.5
%
0.5
LSB rms
(Unused channels grounded)
Programmable Gain Amplifier
Resolution
Gain
9
bits
7.34
0.66 
* PGA [ 8 : 0 ]
511
V/V
Max gain, each channel
GMAX
7.7
V/V
Min gain, each channel
GMIN
0.65
V/V
Analogue to Digital Converter
Resolution
10
bits
Speed
60
MSPS
Full-scale input range
LOWREFS=0
2
V
(2*(VRT-VRB))
LOWREFS=1
1.2
V
Notes:
1.
Full-scale input voltage denotes the differential input signal amplitude (VIN-VRLC in non-CDS mode, VIN-RESET
level in CDS mode) that can be gained to match the ADC full-scale input range.
2.
Input signal limits are the limits within which each input voltage and VRLC reference must lie.
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GENERAL CHARACTERISTICS
Test Conditions
AVDD = DVDD = 3.3V, AGND = DGND = 0V, TA = 25C
PARAMETER
SYMBOL
TEST
CONDITIONS
MIN
TYP
MAX
UNIT
References
Upper reference voltage
VRT
Lower reference voltage
VRB
Input return bias voltage
VRX
Diff. Reference voltage (VRTVRB)
VRTB
LOWREFS=0
2.05
V
LOWREFS=1
1.85
V
LOWREFS=0
1.05
V
LOWREFS=1
1.25
V
1.25
V
LOWREFS=0
1.0
V
LOWREFS=1
0.6
V
1

Output resistance VRT, VRB, VRX
VRLC/Reset-Level Clamp (RLC)
RLC switching impedance
50

VRLC short-circuit current
2
mA
VRLC output resistance
VRLC = 0 to AVDD
1
RLCDAC resolution
RLCDAC step size

2
VRLC Hi-Z leakage current
A
4
bits
VRLCSTEP
RLCDACRNG=0,
0.173
V/step
VRLCSTEP
RLCDACRNG=1,
0.11
V/step
0.097
V/step
LOWREFS=0
VRLCSTEP
RLCDACRNG=1,
LOWREFS=1
RLCDAC output voltage at
code 0(hex)
RLCDAC output voltage at
code F(hex)
VRLCBOT
RLCDACRNG=0,
RLCDAC[3:0]=0000,
0.4
V
VRLCBOT
RLCDACRNG=1,
RLCDAC[3:0]=0000,
0.4
V
VRLCTOP
RLCDACRNG=0,
RLCDAC[3:0]=1111,
3.0
V
VRLCTOP
RLCDACRNG=1,
RLCDAC[3:0]=1111,
LOWREFS = 0
2.05
V
VRLCTOP
RLCDACRNG=1,
RLCDAC[3:0]=1111,
LOWREFS = 1
1.85
V
VRLC DNL
-0.5
+0.5
LSB
VRLC INL
-0.5
+0.5
LSB
Offset DAC, Monotonicity Guaranteed
Resolution
8
bits
Differential non-linearity
DNL
0.1
0.5
LSB
Integral non-linearity
INL
0.75
1
LSB
Step size
2.04
Output voltage
mV/step
Code 00(hex)
-250
mV
Code FF(hex)
+250
mV
DIGITAL SPECIFICATIONS
Digital Inputs
0.7 
DVDD
High level input voltage
VIH
Low level input voltage
VIL
0.2 
DVDD
V
High level input current
IIH
1
A
1
A
Low level input current
IIL
Input capacitance
CI
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V
5
pF
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Test Conditions
AVDD = DVDD = 3.3V, AGND = DGND = 0V, TA = 25C
PARAMETER
SYMBOL
TEST
CONDITIONS
MIN
High level output voltage
VOH
IOH = 1mA
DVDD
– 0.5
Low level output voltage
VOL
IOL = 1mA
High impedance output current
IOZ
TYP
MAX
UNIT
Digital Outputs
V
0.5
V
1
A
Digital IO Pins
0.7 
DVDD
Applied high level input voltage
VIH
Applied low level input voltage
VIL
High level output voltage
VOH
IOH = 1mA
Low level output voltage
VOL
IOL = 1mA
Low level input current
IIL
High level input current
IIH
Input capacitance
CI
Output Impedance
Ro
High impedance output current
IOZ
V
0.2 
DVDD
DVDD
– 0.5
V
0.5
V
1
A
1
A
5
Io = 1mA
V
pF
38
Ω
1
A
Supply Currents
Analogue supply current  active
Digital supply current  active
Total supply current  active
Total supply current  full power
down mode
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FOL_EN=0
93
mA
FOL_EN=1
141
mA
FOL_EN=0
7.3
mA
FOL_EN=1
8
mA
FOL_EN=0
100.3
mA
FOL_EN=1
149
mA
150
200
A
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INPUT VIDEO SAMPLING
CDS MODE (CDS=1)
Figure 1 Three-channel CDS Operation (CDS=1)
Figure 2 Two-channel CDS Operation (CDS=1)
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Figure 3 One-channel CDS Operation (CDS=1)
Notes:
1.
The relationship between input video signal and sample points is controlled by VSMP and RSMP.
2.
When VSMP is high the input video signal is connected to the Video sampling capacitors.
3.
When RSMP is high the input video signal is connected to the Reset sampling capacitors.
4.
Non-CDS operation is also possible; VSMP, MCLK timing is unchanged, RSMP is not required in this mode but can be
used to control input clamping.
NON-CDS MODE (CDS=0)
Figure 4 Three-channel non-CDS Operation (CDS=0)
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Figure 5 Two-channel non-CDS Operation (CDS=0)
Figure 6 One-channel non-CDS Operation (CDS=0)
Notes:
1.
2.
The relationship between input video signal and sample points is controlled by VSMP and RSMP.
When VSMP is high the input video signal is connected to the Video sampling capacitors and VRLC is connected to
the Reset sampling capacitors.
3.
RSMP is not required in this mode but can be used to control input clamping.
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Test Conditions
AVDD = DVDD = 3.3V, AGND = DGND = 0V, TA = 25C.
PARAMETER
SYMBOL
MCLK period, ACLKDIV=00 (default)
TEST CONDITIONS
MIN
TYP
MAX
UNITS
tPER
12 or 16 bit
25
ns
tPER
8 or 10 bit
16.67
ns
MCLK high period
tMCLKH
0.5
MCLK
periods
MCLK low period
tMCLKL
0.5
MCLK
periods
MCLK Duty Cycle
45:55
55:45
%
RSMP pulse high time
tRSD
3
ns
VSMP pulse high time
tVSD
2
ns
RSMP falling to VSMP rising time
tRSFVSR
0
ns
MCLK rising to VSMP rising time
tMRVSR
3
ns
MCLK falling to VSMP falling time
tMFVSF
7
ns
VSMP falling to MCLK rising time
tVSFMR
0
ns
tMF1RSF
7
ns
3-channel mode pixel period
tPR3
3
MCLK
periods
2-channel mode pixel period
tPR2
2
MCLK
periods
1-channel mode pixel period
tPR1
1
MCLK
periods
st
1 MCLK falling edge after VSMP falling
to RSMP falling time
st
Output latency. From 1 rising edge of
MCLK after VSMP falling to data output
LAT
OPDEL[3:0]=0000,
7
ACLKDIV=00
MCLK
periods
Notes:
1.
Parameters are measured at 50% of the rising/falling edge.
OUTPUT DATA TIMING
OEB
tPZE
OP
tPEZ
Hi-Z
Hi-Z
Figure 7 Output Enable/Disable Timing from OEB Pin
MCLK
tPAZE
OP
tPD
Hi-Z
tPAEZ
Hi-Z
Figure 8 Output Enable/Disable Timing with AUTOZ=1
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Test Conditions
AVDD = DVDD = 3.3V, AGND = DGND = 0V, TA = 25C, MCLK = 40MHz unless otherwise stated..
PARAMETER
Output propagation delay
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNITS
tPD
IOH & IOL = 1mA
3
4.5
7
ns
AUTOZ=0
Output enable time, from OEB falling edge
tPZE
5
ns
Output disable time, from OEB rising edge.
tPEZ
3
ns
Automatic output enable time from MCLK
rising edge.
tPAZE
AUTOZ=1, OEDEL=01
5.5
ns
Automatic output disable time from MCLK
rising edge.
tPAEZ
AUTOZ=1, all OEDEL
settings
3
ns
SERIAL INTERFACE
Figure 9 Serial Interface Timing
Test Conditions
AVDD = DVDD = 3.3V, AGND = DGND = 0V, TA = 25C, unless otherwise stated.
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNITS
SCK period
tSPER
83.3
ns
SCK high
tSCKH
37.5
ns
SCK low
tSCKL
37.5
ns
SDI set-up time
tSSU
6
ns
SDI hold time
tSH
6
ns
SCK Rising to SEN Rising
tSCRSER
37.5
ns
SCK Falling to SEN Falling
tSCFSEF
12
ns
SEN to SCK set-up time
tSEC
12
ns
SEN pulse width
tSEW
60
ns
SEN low to SDO = Register data
tSERD
30
ns
SCK low to SDO = Register data
tSCRD
30
ns
SCK low to SDO = ADC data
tSCRDZ
30
ns
Note:
Figure 3 Parameters are measured at 50% of the rising/falling edge
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INTERNAL POWER ON RESET CIRCUIT
Figure 10 Internal Power On Reset Circuit Schematic
The WM8224 includes an internal Power-On-Reset Circuit, as shown in Figure 10, which is used to
reset the digital logic into a default state after power up. The POR circuit is powered from AVDD and
monitors DVDD. It asserts PORB low if AVDD or DVDD is below a minimum threshold.
DVDD
Vpord_on
DGND
AVDD
Vpora
Vpora_off
AGND
HI
INTERNAL PORB
LO
No Power
POR
Undefined
Internal
POR active
Device Ready
Internal POR active
Figure 11 Typical Power up Sequence where AVDD is Powered before DVDD
Figure 11 shows a typical power-up sequence where AVDD is powered up first. When AVDD rises
above the minimum threshold, Vpora, there is enough voltage for the circuit to guarantee PORB is
asserted low and the chip is held in reset. In this condition, all writes to the control interface are
ignored. Now AVDD is at full supply level. Next DVDD rises to Vpord_on and PORB is released high
and all registers are in their default state and writes to the control interface may take place.
On power down, where AVDD falls first, PORB is asserted low whenever AVDD drops below the
minimum threshold Vpora_off.
Figure 12 Typical Power up Sequence where DVDD is Powered before AVDD
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Figure 12 shows a typical power-up sequence where DVDD is powered up first. First it is assumed
that DVDD is already up to specified operating voltage. When AVDD goes above the minimum
threshold, Vpora, there is enough voltage for the circuit to guarantee PORB is asserted low and the
chip is held in reset. In this condition, all writes to the control interface are ignored. When AVDD rises
to Vpora_on, PORB is released high and all registers are in their default state and writes to the
control interface may take place.
On power down, where DVDD falls first, PORB is asserted low whenever DVDD drops below the
minimum threshold Vpord_off.
SYMBOL
MIN
TYP
MAX
UNIT
Vpora
0.4
0.6
0.8
V
Vpora_on
0.9
1.2
1.6
V
Vpora_off
0.4
0.6
0.8
V
Vpord_on
0.5
0.7
0.9
V
Vpord_off
0.4
0.6
0.8
V
Table 1 Typical POR Operation (typical values, not tested)
Note: It is recommended that every time power is cycled to the WM8224 a software reset is written to
the software register to ensure that the contents of the control registers are at their default values
before carrying out any other register writes.
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DEVICE DESCRIPTION
INTRODUCTION
A block diagram of the device showing the signal path is presented on the front page of this
datasheet.
The WM8224 samples up to three inputs (RINP, GINP and BINP) simultaneously. The device then
processes the sampled video signal with respect to the video reset level or an internally/externally
generated reference level using between one and three processing channels.
Each processing channel consists of an Input Sampling block with optional Reset Level Clamping
(RLC) and Correlated Double Sampling (CDS), an 8-bit programmable offset DAC and a 9-bit
Programmable Gain Amplifier (PGA).
The processing channel outputs are switched alternately by a 3:1 multiplexer to the ADC input.
The ADC then converts each resulting analogue signal to a digital word. The digital output from the
ADC is presented in a variety of possible output formats onto the output bus, OP[11:0]. The twelve
output pins can be set to a high impedance state using either the OEB control pin or the OPD register
bit.
On-chip control registers determine the configuration of the device, including the offsets and gains
applied to each channel. These registers are programmable via a serial interface.
The device has a Black-Level Calibration function which allows the D.C. offset determined during the
optically-black pixels at the beginning of the linear sensor to be removed during the image-pixels.
CONFIGURABLE RESOLUTION OF ADC
The WM8224 has a configurable ADC resolution. The default setting is 16 bits resolution. This can
be changed by the user by changing a register setting.
The register RES[1:0] can be changed to alter the resolution from 16 bits to either 12, 10 or 8 bits
resolution.
INPUT SAMPLING
The WM8224 can sample and process up to three inputs through one to three processing channels
as follows:
Colour Pixel-by-Pixel: The three inputs (RINP, GINP and BINP) are simultaneously sampled for
each pixel and a separate channel processes each input. The signals are then multiplexed into the
ADC, which converts all three inputs within the pixel period.
Two Channel Pixel-by-pixel: Two input channels (RINP and GINP, RINP and BINP, or GINP and
BINP) are simultaneously sampled for each pixel and a separate channel processes each input. The
signals are then multiplexed into the ADC, which converts both inputs within the pixel period. The
unused channel can be changed via the control interface. The unused channel is powered down
when this mode is selected.
Monochrome: A single chosen input (RINP, GINP, or BINP) is sampled, processed by the
corresponding channel, and converted by the ADC. The choice of input channel can be changed via
the control interface. The unused channels are powered down when this mode is selected.
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RESET LEVEL CLAMPING (RLC)
To ensure that the signal applied to the WM8224 lies within the supply voltage range (0V to AVDD)
the output signal from a CCD is usually level shifted by coupling through a capacitor, CIN. The RLC
circuit clamps the WM8224 side of this capacitor to a suitable voltage through a CMOS switch during
the CCD reset period (pixel clamping) or during the black pixels (line clamping). In order for clamping
to produce correct results the input voltage during the clamping must be a constant value.
Note that if the ac coupling capacitor (CIN) is used in non-CDS mode (CDS=0), then to minimise code
drift, line clamping should be used and internal input voltage buffers enabled using the FOL_EN
register bit. Alternatively, if the input signal contains a stable reference/reset level then pixel clamping
should be used, and the voltage buffers need not be enabled.
The WM8224 allows the user to control the RLC switch in a variety of ways as illustrated in Figure 13.
This figure shows a single channel, however all 3 channels are identical, each with its own clamp
switch controlled by the common CLMP signal.
The method of control chosen depends upon the characteristics of the input video. The RLCEN
register bit must be set to 1 to enable clamping, otherwise the RLC switch cannot be closed (by
default RLCEN=1).
Note that unused inputs should be left floating, or grounded through a decoupling capacitor, if reset
level clamping is used.
Figure 13 RLC Clamp Control Options
When an input waveform has a stable reference level on every pixel it may be desirable to clamp
every pixel during this period. Setting CLMPCTRL=0 means that the RLC switch is closed whenever
the RSMP input pin is high, as shown in Figure 14.
INPUT VIDEO
SIGNAL
reference
("black") level
video level
MCLK
VSMP
RSMP
RLC switch control
"CLMP"
(RLCEN=1,CLMPCTRL=0)
Video sample taken on
fallling edge of VSMP
Reset/reference sample taken
on fallling edge of RSMP
RLC switch closed
when RSMP=1
Figure 14 Reset Level Clamp Operation (CLMPCTRL=0), CDS operation shown, non-CDS also possible
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In situations where the input video signal does not have a stable reference level it may be necessary
to clamp only during those pixels which have a known state (e.g. the dummy, or “black” pixels at the
start or end of a line on most image sensors). This is known as line-clamping and relies on the input
capacitor to hold the DC level between clamp intervals. In non-CDS mode (CDS=0) this can be done
directly by controlling the RSMP input pin to go high during the black pixels only. Note that internal
input voltage buffers should be enabled using the FOL_EN register bit when using this mode of
operation.
Alternatively it is possible to use RSMP to identify the black pixels and enable the clamp at the same
time as the input is being sampled (i.e. when VSMP is high and RSMP is high). This mode is enabled
by setting CLMPCTRL=1 and the operation is shown in Figure 15.
unstable
reference level
INPUT VIDEO
SIGNAL
dummy or
"black" pixel
video level
MCLK
Video and reference sample
taken on fallling edge of VSMP
VSMP
RSMP
RLC switch control,
"CLMP"
(RLCEN=1,CLMPCTRL=1)
RLC switch closed when RSMP=1 &&
VSMP=1 (during "black" pixels)
Figure 15 Reset Level Clamp Operation (CLMPCTRL=1), non-CDS mode only
RLCEN
CLAMPCTRL
OUTCOME
0
X
RLC is not enabled. RLC switch is always open.
When input is DC coupled and within supply
rails.
1
0
RLC switch is controlled directly from RSMP input
pin:
When ASIC explicitly provides a reset sample
signal and the input video waveform has a
suitable reset level.
RSMP=0: switch is open
USE
RMSP=1: switch is closed
1
1
VSMP applied as normal, RSMP is used to
indicate the location of black pixels
RLC switch is controlled by logical combination of
RSMP and VSMP:
RSMP && VSMP = 1: switch is closed
When clamping during the video period of black
pixels or there is no stable per-pixel reference
level.
This method of operation is generally only
sensible in non-CDS mode.
Switch is re-opened when:
VSMP=0 (non-CDS mode)
VSMP=0 and RSMP=0 (CDS mode)
Table 2 Reset Level Clamp Control Summary
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CDS/NON-CDS PROCESSING
For CCD type input signals, containing a fixed reference/reset level, the signal may be processed
using Correlated Double Sampling (CDS), which will remove pixel-by-pixel common mode noise. With
CDS processing the input waveform is sampled at two different points in time for each pixel, once
during the reference/reset level and once during the video level. To sample using CDS, register bit
CDS must be set to 1 (default). This causes the signal reference to come from the video reference
level as shown in Figure 16.
The video sample is always taken on the falling edge of the input VSMP signal (VS). In CDS-mode
the reset level is sampled on the falling edge of the RSMP input signal (RS).
For input signals that do not contain a reference/reset level (e.g. CIS sensor signals), non-CDS
processing is used (CDS=0). In this case, the video level is processed with respect to the voltage on
pin VRLC/VBIAS. The VRLC/VBIAS voltage is sampled at the same time as VSMP samples the
video level in this mode. Note that if the ac coupling capacitor (CIN) is used in non-CDS mode
(CDS=0), then to minimise code drift, line clamping should be used and internal input voltage buffers
enabled using the FOL_EN register bit. Alternatively, if the input signal contains a stable
reference/reset level then pixel clamping should be used, and the voltage buffers need not be
enabled.
Figure 16 CDS/non-CDS Input Configuration
OFFSET ADJUST AND PROGRAMMABLE GAIN
The output from the CDS block is a differential signal, which is added to the output of an 8-bit Offset
DAC to compensate for offsets and then amplified by a 9-bit PGA. The gain and offset for each
channel are independently programmable by writing to control bits DAC[7:0] and PGA[8:0].
The gain characteristic of the WM8224 PGA is shown in Figure 17. Figure 18 shows the maximum
device input voltage that can be gained up to match the ADC full-scale input range (default=2V).
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3.5
8
7
Max i/p V oltage
LOWREFS=0
3
Max i/p V oltage
LOWREFS=1
6
Input Voltage Range (V)
2.5
PGA Gain (V/V)
5
4
3
2
1.5
1
2
0.5
1
0
0
128
256
384
Gain Code (PGA[8:0])
Figure 17 PGA Gain Characteristic
512
0
0
128
256
Gain Code (PGA[8:0])
384
512
Figure 18 Peak Input Voltage to Match ADC Full-scale Range
ADC INPUT BLACK LEVEL ADJUST
The output from the PGA can be offset to match the full-scale range of the differential ADC (2*[VRTVRB]).
For negative-going input video signals, a black level (zero differential) output from the PGA should be
offset to the top of the ADC range by setting register bits PGAFS[1:0]=10. This will give an output
code of FFFF (hex) from the WM8224 for zero input. If code zero is required for zero differential input
then the INVOP bit should be set.
For positive going input signals the black level should be offset to the bottom of the ADC range by
setting PGAFS[1:0]=11. This will give an output code of 0000 (hex) from the WM8224 for zero input.
Bipolar input video is accommodated by setting PGAFS[1:0]=00 or PGAFS[1:0]=01. Zero differential
input voltage gives mid-range ADC output, 7FFF (hex).
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Figure 19 ADC Input Black Level Adjust Settings
OVERALL SIGNAL FLOW SUMMARY
Figure 20 represents the processing of the video signal through the WM8224.
INPUT
SAMPLING OFFSET DAC PGA
BLOCK
BLOCK
BLOCK
V1
+
VIN
-
V2
++
X
V3
analo
g
x (65535/VFS)
+0
if PGAFS[1:0]=11
+65535 if PGAFS[1:0]=10
+32768 if PGAFS[1:0]=0x
CDS = 1
PGA gain
A= 0.66+PGA[8:0]x7.34/511
VRESET
OUTPUT
INVERT
BLOCK
ADC BLOCK
D1
digita
l
D2
OP pins
D2 = D1 if INVOP = 0
D2 = 65535-D1 if INVOP = 1
CDS = 0
VVRLC
CDACPD=1
Offset
DAC
CDACPD=0
RLC
DAC
See parametrics for
DAC voltages.
250mV*(DAC[7:0]-127.5)/127.5
VIN is RINP or GINP or BINP
VRESET is VIN sampled during reset clamp
VRLC is voltage applied to VRLC/VBIAS pin
CDS, CDACPD,CDAC[3:0], DAC[7:0],
PGA[8:0], PGAFS[1:0] and INVOP are set
by programming internal control registers.
CDS=1 for CDS, 0 for non-CDS
Figure 20 Overall Signal Flow
The INPUT SAMPLING BLOCK produces an effective input voltage V1. For CDS, this is the
difference between the input video level VIN and the input reset level VRESET. For non-CDS this is the
difference between the input video level VIN and the voltage on the VRLC/VBIAS pin, VVRLC, optionally
set via the RLC DAC.
The OFFSET DAC BLOCK then adds the amount of fine offset adjustment required to move the
black level of the input signal towards 0V, producing V2.
The PGA BLOCK then amplifies the white level of the input signal to maximise the ADC range,
outputting voltage V3.
The ADC BLOCK then converts the analogue signal, V3, to a 16-bit unsigned digital output, D1.
The digital output is then inverted, if required, through the OUTPUT INVERT BLOCK to produce D2.
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CALCULATING THE OUTPUT CODE FOR A GIVEN INPUT
The following equations describe the processing of the video and reset level signals through
the WM8224.
INPUT SAMPLING BLOCK: INPUT SAMPLING AND REFERENCING
If CDS = 1, (i.e. CDS operation) the previously sampled reset level, VRESET, is subtracted from the
input video, VIN (= RINP, GINP or BINP).
V1
=
VIN – VRESET
Eqn. 1
If CDS = 0, (non-CDS operation) the simultaneously sampled voltage on pin VRLC is subtracted
instead.
V1
=
VIN – VVRLC
Eqn. 2
If VRLCDACPD = 1, VVRLC is an externally applied voltage on pin VRLC/VBIAS.
If VRLCDACPD = 0, VVRLC is the output from the internal RLC DAC.
VVRLC
=
(VRLCSTEP  RLC DAC[3:0]) + VRLCBOT
Eqn. 3
VRLCSTEP is the step size of the RLC DAC and VRLCBOT is the minimum output of the RLC DAC.
OFFSET DAC BLOCK: OFFSET (BLACK-LEVEL) ADJUST
The resultant signal V1 is added to the Offset DAC output.
V2
=
V1 + {250mV  (DAC[7:0]-127.5) } / 127.5
Eqn. 4
PGA NODE: GAIN ADJUST
The signal is then multiplied by the PGA gain.
V3
=
V2  (0.66 + PGA[8 :0]x7.34/511)
Eqn. 5
ADC BLOCK : ANALOGUE-DIGITAL CONVERSION
The analogue signal is then converted to a 16-bit unsigned number, with input range configured by
PGAFS[1:0].
D1[15:0] = INT{ (V3 /VFS)  65535} + 32767
PGAFS[1:0] = 00 or 01
Eqn. 6
D1[15:0] = INT{ (V3 /VFS)  65535}
PGAFS[1:0] = 11
Eqn. 7
D1[15:0] = INT{ (V3 /VFS)  65535} + 65535
PGAFS[1:0] = 10
Eqn. 8
where the ADC full-scale range, VFS = 2V when LOWREFS=0 and VFS = 1.2V when LOWREFS=1.
OUTPUT INVERT BLOCK: POLARITY ADJUST
The polarity of the digital output may be inverted by control bit INVOP.
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D2[15:0] = D1[15:0] (INVOP = 0)
Eqn. 9
D2[15:0] = 65535 – D1[15:0]
Eqn. 10
(INVOP = 1)
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OUTPUT FORMATS
The output from the WM8224 can be presented in several different formats under control of the
OPFORM register bit as shown in Figure 21. In addition the data can be presented at different
resolutions.
Figure 21 Output Data Formats
OPFORM
OUTPUT
FORMAT
OUTPUT
PINS
0
Multiplexed
OP[11:4]
RES[1:0]
RESOLUTION
OUTPUT
11
16-bit
A[7:0] = {d15, d14, d13, d12, d11, d10, d9, d8}
10
12-bit
A[7:0] = {d15, d14, d13, d12, d11, d10, d9, d8}
B[7:0] = {d7, d6, d5, d4, 0, 0, 0, 0}
01
10-bit
A[7:0] = {d15, d14, d13, d12, d11, d10, d9, d8}
B[7:0] = {d7, d6, 0, 0, 0, 0, 0, 0}
Not valid
B[7:0] = {d7, d6, d5, d4, d3, d2, d1,d0}
1
Parallel
00
8-bit
OP[11:0]
11
16-bit
Not valid
OP[11:0]
10
12-bit
A[11:0] ={ d15, d14, d13, d12, d11, d10, d9,
d8,d7,d6,d5,d4}
OP[11:2]
01
10-bit
A[9:0] = {d15, d14, d13, d12, d11, d10, d9, d8,d7,d6}
OP[11:4]
00
8-bit
A[7:0] = {d15, d14, d13, d12, d11, d10, d9, d8}
Table 3 Details of Output Data Formats (as shown in Figure 21)
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PROGRAMMABLE AUTOMATIC BLACK LEVEL CALIBRATION
The Programmable Automatic Black-Level Calibration (BLC) function is to adjust the D.C. offset of the
output data such that the digital output code for black pixels is calibrated to a target black level value.
The D.C. offset is determined during the optically-black pixels at the beginning of the linear sensor,
and removed during the image-pixels as shown in Figure 22.
Black Pixel Period
Image Pixel Period
Determine Black
Level Offset
Remove Black Level Offset
from Image Pixels
Figure 22 Linear Sensor Model
The automatic black level calibration operates assuming 12 bits ADC resolution. Adjustments to
calculations must be made for different ADC resolutions.
The black level calibration process occurs in two stages as shown in Figure 23 below:

Coarse Adjust Calibration: This is a mixed signal loop which removes the coarse offset by
adjusting the offset DAC.

Fine Adjust Calibration: This is a digital loop which removes the remaining offset with
better noise tolerance, utilising ADC over-range to improve the dynamic range of the
system.
PGA
Input Black Level V1
Offset
DAC
Adjusted
ADC Output
ADC
Coarse Adjust
Calibration
Fine Adjust
Calibration
Mixed
Signal
LOOP
Digits
Digital
LOOP
Digits
TARGET BL
Figure 23 BLC Top-Level Circuitry
TARGET CODES
The user must specify a target black level for each Red, Green and Blue channel through the
registers TARGETR, TARGETG and TARGETB. If, during the black-pixel period, the average ADC
output code was, for example, 100 and the user specified the target black level code to be 10, the
BLC circuitry would determine 90 codes should be subtracted from the ADC output. These 90 codes
will then be subtracted from every image-pixel code output from the ADC.
Note – changing the PGA gain affects the black-level through the device; the gain should therefore
not be changed during a BLC procedure. If the PGA gain changes, then the BLC routine should be
re-run.
The automatic black level calibration feature operates with the assumption of a 12bit ADC resolution.
The register settings for Target Codes (TARGETx[7:0]) should be set differently depending on the
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ADC resolution being used. As TARGETx[7:0] is an 8 bit register, the 4 MSBs of a data output code
cannot be changed.
16bit ADC Resolution
For 16bit resolution the target code entered into TARGETx[7:0] will ignore the 4 MSBs and 4 LSBs of
the 16-bit data output. For example if the desired code out is 0000111111110001, the value entered
into TARGETx[7:0] would be 11111111.
12bit ADC Resolution
For 12bit resolution the 4 MSBs of the 12 bit data output code will be ignored. For example if the
desired code out is 000011111111, the value entered into TARGETx[7:0] would be 11111111.
10bit ADC Resolution
For 10bit resolution the 4 MSBs of the 10bit data output code will be ignored. The 2 LSBs of the
target code should be set to ‘00’. For example if the desired code out is 0000111111, the value
entered into TARGETx[7:0] would be 11111100.
8bit ADC Resolution
For 8bit resolution the 4 MSBs of the 8bit data output code will be ignored. The 4 LSBs of the target
code should be set to ‘0000’. For example if the desired code out is 00001111, the value entered into
TARGETx[7:0] would be 11110000.
INDICATING THE START OF A BLC PROCEDURE
The start of a line is required to be indicated to the WM8224 to allow the black-pixel period to be
located. This can be achieved by two methods. The register TG_METHOD is set to reflect which
method is to be used.
METHOD 1: OEB PIN
The OEB pin can be shared with the BLC function to indicate the start of a line if the OEB functionality
is not required. To indicate the start of a line, send a line synchronisation pulse, TG, on the OEB pin.
It must be high for at least one rising edge of MCLK. The TG_METHOD register must be set to either
‘10’ or ‘11’ depending on whether positive or negative edge triggering is required, as shown in Figure
24.
Figure 24 Start of Line Indicator Using TG on the OEB Pin
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METHOD 2: REGISTER WRITE
The start of a line can also be indicated using a register write to TG_REG. The first rising edge of
MCLK after TG_REG goes high will indicate the start of the line. TG_REG shall be automatically set
to zero by the device. This process can be repeated to indicate the start of a second line, as shown
in Figure 25. Set TG_METHOD to ‘00’
Figure 25 Start of Line Indicator Using TG_REG
BLC DURATION CONTROL
DUMMY PIXEL DELAY
Once the start of line has been determined there can be a delay to allow for the dummy pixels at the
start of the sensor to be ignored. This is controlled by BLC_DEL, which is the number of pixels there
should be between the start of line indicator and the start of the BLC routine.
The register BPIX_AVAIL must also be set up for the number of black pixels available to carry out the
calibration. The durations of the Coarse Adjust Calibration and Fine Adjust calibration can then be
determined as detailed below.
Figure 26 BLC Duration Control
COARSE ADJUST CALIBRATION ITERATION DURATION
The duration of one iteration of the Coarse Adjust is an integer number of VSMP periods. The exact
number of VSMP periods depends on the MCLK:VSMP ratio and the number of channels used. The
implementation ensures that there are at least a certain number of MCLK’s per Coarse Adjust
iteration as shown in Table 4.
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MODE
MINIMUM NO. OF MCLKS PER
COARSE ADJUST ITERATION
3-Channel
11
2-Channel
10
Mono
9
Table 4 Modes vs MCLKs for Coarse Iterations
The BLC design rounds the Coarse Adjust iteration duration up to a whole number of pixels (i.e. the
iteration duration will be a whole number of VSMP periods).
FINE ADJUST CALIBRATION DURATION
The Fine Adjust calibration duration is determined by the number of remaining black pixels after the
coarse adjust has taken place.
BLC TEST MODE
This mode allows the status of the BLC to be seen on the 2 LSBs of the output data pins OP[1:0].
This mode could be enabled during the setup stage of the device to ensure that the black level
calibration does not encroach on the active pixel data. Set the STATEOUT register to enable this
mode. Once the BLC register values have been determined this register should be disabled. Table 5
shows the description of the output data.
DATA ON OP[1:0]
DESCRIPTION
00
No BLC
01
Dummy Pixels
10
Coarse Adjust Calibration
11
Fine Adjust Calibration
Table 5 Test Mode Outputs
BLC WORKED EXAMPLE:
Below is an example of how to configure the WM8224 for Black Level Calibration.
Assumptions
MCLK frequency
= 40MHz
VSMP frequency
= 13.33MHz
Mode of operation
= 3 Channel Mode
Black pixels on sensor
= 50
Dummy pixels on sensor
= 20
The following stages set up the Black Level calibration although not all stages may be required
depending on the application:
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1.
Set up the Dummy Pixel Delay
2.
Define the Coarse Adjust Calibration
3.
Define the Fine Adjust Calibration
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1.
Dummy Pixel delay
Set BLC_DEL, the number of dummy pixels for the sensor
BLC_DEL = ‘0010100’
The duration for this will then be BLC_DEL * VSMP period
Dummy pixel delay = 20*75ns = 1.5us
2.
Define the coarse adjust loop
When setting the coarse adjust calibration it is necessary to bear in mind the following:

The number of black pixels available

The coarse adjust iteration duration

The number of iterations required.
Step 1: Set up BPIX_AVAIL with the number of available black pixels for the sensor.
BPIX_AVAIL = ’0000110010’
Step 2:
Calculate MCLK:VSMP ratio
40:13.33 = 3:1
Step 3:
Calculate the duration of the iteration in no. of pixels (round up value). Refer to Table 4 for
the number of MCLK’s per Coarse Adjust iteration
no. of MCLKs
 no. of pixels
(MCLK : VSMP )ratio
no. of MCLKs
(MCLK : VSMP )ratio

11
 3.67
3
Round up this value to give the no of pixels per iteration
= 4 pixels per iteration
Note: The device will automatically calculate this value.
Step 4:
Set the register CADUR for max number of iterations.
CADUR = 2
Theoretically there can be 7 coarse adjust iterations during the black pixel period. However, in most
cases 2 would be sufficient depending on the number of black pixels available to allow time for the
fine adjust loop.
3.
Fine Adjust Calibration
Step 1:
Enable Register FA_EN to allow for fine adjust calibration
Step 2:
The time available for fine adjustment is determined by the no. of remaining
black pixels after the coarse adjust has taken place.
BPIX_AVAIL – (CADUR* iteration duration)
50 – (2*4)
= 42 pixels
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BLC SCENARIOS OF OPERATION
The BLC can be used in various ways to suit the application, for example calibration can be done
once per page or once per line. Register set up should be carried out before the start of a frame and
is not required to be done on a line by line basis if using the Method 1 OEB PIN method. Five
potential scenarios of operation are suggested below.
Note: The registers FRAME_START and SEQ_START when set high by the user will automatically
be set low by the device.
SCENARIO 1
st
Coarse Adjust Calibration enabled for the 1 line, Fine Adjust Calibration enabled every line with the
Fine Adjust Calibration result recalculated every line. This scenario is suitable for dealing with large
amounts of d.c. drift throughout a frame; but this is at a cost of potential line-by-line variation in the
Fine Adjust result (dependent on sensor noise and the PGA gain). Table 6 shows which registers are
required for this scenario with example settings.
SETUP
REGISTER
BPIX_AVAIL
CADUR
FRAME_START
FA_EVERYLINE
Value
50
2
1
1
Table 6 Example Register Settings for Scenario 1
Figure 27 Scenario 1
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SCENARIO 2
st
Coarse Adjust and Fine Adjust Calibration enabled for the 1 line, with the Fine Adjust result updated
st
on the 1 line only. This scenario is suitable for adjusting for black-level d.c. drift on a frame-by-frame
basis; there will be no line-by-line variation in the black-level from the BLC circuitry. Table 7 shows
which registers are required for this scenario with example settings.
SETUP
REGISTER
BPIX_AVAIL
CADUR
FRAME_START
Value
50
2
1
Table 7 Example Register Settings for Scenario 2
Figure 28 Scenario 2
SCENARIO 3
st
Coarse Adjust Calibration enabled for the 1 line, Fine Adjust Calibration enabled every line with the
Fine Adjust result accumulated throughout frame and used every line. This scenario allows any
variation in the black-level to be tracked throughout the frame by accumulating the Fine Adjust result
over multiple lines. This method does not deal with as large amounts of d.c. drift throughout the
frame as scenario 1, but it will produce less line-by-line variation. Table 8 shows which registers are
required for this scenario with example settings.
SETUP
REGISTER
BPIX_AVAIL
CADUR
FRAME_START
FA_EVERYLINE
FA_ACCUM
Value
50
2
1
1
1
Table 8 Example Register Settings for Scenario 3
Figure 29 Scenario 3
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SCENARIO 4
st
Coarse Adjust Calibration enabled for 1 line, Fine Adjust Calibration enabled every line with the Fine
Adjust result accumulated throughout frame and used at start of next frame. This scenario is
intended to be used with a sequence of multiple frames, the first frame being used as a calibration
frame. This is good for use with sensors containing very few black-pixels as the black-level offset can
be calculated over an entire frame and there will be no line-by-line variation in the black-level from the
BLC circuitry. Table 9 shows which registers are required for this scenario with example settings.
SETUP
REGISTER
BPIX_AVAIL
CADUR
FRAME_START
FRAME_SEQ
SEQ_START
FA_EVERYLINE
FA_ACCUM
Value
50
2
1
1
1
1
1
Table 9 Example Register Settings for Scenario 4
Figure 30 Scenario 4
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SCENARIO 5
This scenario utilises the information from a possible calibration black-strip at the start of a scan. The
register LINE_DEL sets the number of lines from the start of the frame that the BLC procedure is to
be performed, so as to coincide with the calibration strip. Table 10 shows which registers are required
for this scenario with example settings.
SETUP REGISTER
BPIX_AVAIL
CADUR
LINE_DEL
FRAME_START
FA_EVERYLINE
Value
1000
2
50
1
1
Table 10 Example Register Settings for Scenario 5
Figure 31 Scenario 5
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REFERENCES
The ADC reference voltages are derived from an internal bandgap reference, and buffered to pins
VRT and VRB, where they must be decoupled to ground. Pin VRX is driven by a similar buffer, and
also requires decoupling. The output buffer from the RLCDAC also requires decoupling at pin
VRLC/VBIAS.
The ADC references can be switched from the default values (VRT=2.05V, VRB=1.05V, ADC input
range=2V) to give a smaller ADC reference range (VRT=1.85V, VRB=1.25V, ADC input range=1.2V)
under control of the LOWREFS register bit. Setting LOWREFS=1 allows smaller input signals to be
accommodated.
Note:
When LOWREFS = 1 the output of the RLCDAC will scale if RLCDACRNG = 1. The max output from
RLCDAC will change from 2.05 to 1.85V and the step size will proportionally reduce.
POWER MANAGEMENT
Power management for the device is performed via the Control Interface. By default the device is fully
enabled. The EN bit allows the device to be fully powered down when set low. Individual blocks can
be powered down using the bits in Setup Register 5. When in MONO or TWOCHAN mode the
unused input channels are automatically disabled to reduce power consumption.
Note: It is recommended that if the clocks are removed from the device, the device should be
powered down using the EN bit in Setup Reg 1.
CONTROL INTERFACE
The internal control registers are programmable via the serial digital control interface. The register
contents can be read back via the serial interface on pin OP[11]/SDO.
It is recommended that a software reset is carried out after the power-up sequence, before writing to
any other register. This ensures that all registers are set to their default values (as shown in Table
15).
DEVICE IDENTIFICATION
Up to 3 WM8224 devices can share a common set of serial interface pins. Each device on the
common interface bus must be given a different device ID. The device ID is set by the input pin
DSLCT as shown in Table 11.
DSLCT
DEVICE ID
(ID[1:0])
0
00
1
01
Z
10
Table 11 Device Identification
REGISTER WRITE
Figure 32 shows sequence of operations for performing a register write. Three pins, SCK, SDI and
SEN are used for the control interface. An eight-bit address (id1, id0, a5, 0, a3, a2, a1, a0) is clocked
in through SDI, MSB first, followed by an eight-bit data word (b7, b6, b5, b4, b3, b2, b1, b0), also MSB
first. The device ID bits indicate which device is being written to on a shared control bus. A register
write with device ID set to 11 writes data to all devices on the common bus. Setting address bit a4 to
0 indicates that the operation is a register write. Each bit is latched on the rising edge of SCK. When
the data has been shifted into the device, a rising edge on the SEN pin transfers the data to the
appropriate internal register.
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Figure 32 Control Interface Register Write
A software reset is carried out by writing to Address “000100” with any value of data, (i.e. Data Word
= XXXXXXXX).
REGISTER READ-BACK
Figure 33 shows register read-back in serial mode. Read-back is initiated by writing to the serial bus
as described above but with address bit a4 set to 1, followed by an 8-bit dummy data word. Writing
address (id1, id0, a5, 1, a3, a2, a1, a0) will cause the contents (d7, d6, d5, d4, d3, d2, d1, d0) of
corresponding register in the addressed device to be output MSB first on pin SDO (on the falling edge
of SCK). Note that pin SDO is shared with an output pin, OP[11], and readback will override a highimpedance output on this pin. The next word may be read in to SDI while the previous word is still
being output on SDO.
Figure 33 Serial Interface Register Read-back
MULTIPLE DEVICE OPERATION
Up to 3 WM8224 devices can be configured to share common serial interfaces and output data
buses. In order to accommodate multiple devices on a shared output bus a higher number of MCLKs
per VSMP are required.
When multiple devices are being used the WM8224 can be configured so that the outputs are high
impedance apart from during valid data output by setting the AUTOZ register bit to 1. [Note that
AUTOZ should not be used if the MCLK : VSMP ratio is 1:1.] The output of each device can be
staggered by adjusting the latency via the OPDEL[3:0] register bits, allowing multiple devices to share
the same output bus.
BUS CONTENTION
In 3 channel mode, an MCLK:VSMP ratio of 8:1 (2 devices) or 12:1 (3 devices) is recommended to
give an spare MCLK cycle in which to allow the output data pins to transition in and out of a high
impedance state. However an MCLK:VSMP ratio of 6:1 (2 devices) or 9:1 (3 devices) can be used,
but care must be taken with output timing to prevent bus contention.
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EXAMPLE : TWO DEVICE, 6-CHANNEL, MCLK:VSMP=8:1, OPERATION
Figure 34 shows how two devices can be configured to share a single data bus and a single control
interface bus thus reducing pin count on the receiving ASIC.
Multi Channel Sensor
The timing for this mode is shown in Figure 35.
Figure 34 Two device, 6-channel, MCLK:VSMP=8:1, Schematic
Figure 35 Two device, 6-channel, MCLK:VSMP=8:1, Timing Diagram
OPERATING MULTIPLE DEVICES AT UP TO 60MHZ IN UP TO 16 BIT MODE
If using multiple devices, then up to 16bit operation can be obtained with an MCLK frequency of up to
60MHz, by dividing down the internal MCLK, using ACLKDIV.
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Figure 36 Timing with aclk=mclk/2 (ACLKDIV=01)
Figure 37 Timing with aclk=mclk/3 (ACLKDIV=10)
Figure 38 Invalid rsmp positions
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OPERATING MODES
Table 12 and Table 13 below show the normal operating modes of the device. The MCLK speed can
be changed along with the MCLK:VSMP ratio to achieve the desired sample rate.
16-BIT MODE
NUMBER
OF
CHANNELS
DESCRIPTION
9
3 Devices Used
CDS
AVAILABLE
YES
MAXIMUM
SAMPLE
RATE
4.4 MSPS
TIMING REQUIREMENTS
REGISTER
SETTINGS
MCLK max = 40MHz
MONO = 0
Minimum MCLK:VSMP ratio = 9:1
TWOCHAN = 0
AUTOZ=1
ACLKDIV = 00
6
2 Devices Used
YES
6.6 MSPS
Dev ID
OPDEL[3:0]
00
0000
01
0100
10
1000
MCLK max = 40MHz
MONO = 0
Minimum MCLK:VSMP ratio = 6:1
TWOCHAN = 0
AUTOZ=1
ACLKDIV = 00
9
3 Devices Used
YES
6.6 MSPS
Dev ID
OPDEL[3:0]
00
0000
01
0100
MCLK max = 60MHz
MONO = 0
Minimum MCLK:VSMP ratio = 9:1
TWOCHAN = 0
AUTOZ=1
ACLKDIV = 10
6
2 Devices Used
YES
10 MSPS
Dev ID
OPDEL[3:0]
00
0000
01
0100
10
1000
MCLK max = 60MHz
MONO = 0
Minimum MCLK:VSMP ratio = 6:1
TWOCHAN = 0
AUTOZ=1
ACLKDIV = 01
Dev ID
OPDEL[3:0]
00
0000
01
0100
3
Three channel
Pixel-by-Pixel
YES
13.33 MSPS
MCLK max = 40MHz
MONO = 0
Minimum MCLK:VSMP ratio = 3:1
TWOCHAN = 0
2
Two channel
Pixel-by-Pixel
YES
20 MSPS
MCLK max = 40MHz
MONO = 0
Minimum MCLK:VSMP ratio = 2:1
TWOCHAN = 1
One channel
Pixel-by-Pixel
YES
MCLK max = 40MHz
MONO = 1
Minimum MCLK:VSMP ratio = 1:1
TWOCHAN = 0
1
40 MSPS
Table 12 WM8224 16-bit Normal Operating Modes
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10-BIT MODE
NUMBER
OF
CHANNELS
DESCRIPTION
9
3 Devices Used
CDS
AVAILABLE
YES
MAXIMUM
SAMPLE
RATE
6.6 MSPS
TIMING REQUIREMENTS
REGISTER
SETTINGS
MCLK max = 60MHz
MONO = 0
Minimum MCLK:VSMP ratio = 9:1
TWOCHAN = 0
AUTOZ=1
6
2 Devices Used
YES
10 MSPS
Dev ID
OPDEL[3:0]
00
0000
01
0100
10
1000
MCLK max = 60MHz
MONO = 0
Minimum MCLK:VSMP ratio = 6:1
TWOCHAN = 0
AUTOZ=1
Dev ID
OPDEL[3:0]
00
0000
01
0100
3
Three channel
Pixel-by-Pixel
YES
20 MSPS
MCLK max = 60MHz
MONO = 0
Minimum MCLK:VSMP ratio = 3:1
TWOCHAN = 0
2
Two channel
Pixel-by-Pixel
YES
30 MSPS
MCLK max = 60MHz
MONO = 0
Minimum MCLK:VSMP ratio = 2:1
TWOCHAN = 1
One channel
Pixel-by-Pixel
YES
MCLK max = 60MHz
MONO = 1
Minimum MCLK:VSMP ratio = 1:1
TWOCHAN = 0
1
60 MSPS
Table 13 WM8224 10-bit Normal Operating Modes
Table 14 below shows the different channel mode register settings required to operate the 8224 in 1,
2 and 3 channel modes.
MONO
TWOCHAN
CHAN[1:0]
0
0
XX
0
1
00
MODE DESCRIPTION
3-channel (colour mode)
2-channel mode
Green and Blue channels selected, Red PGA disabled
0
1
01
2-channel mode
Red and Blue channels selected, Green PGA disabled
0
1
10
2-channel mode
Red & Green channels selected, Blue PGA disabled
1
0
00
1-channel (monochrome) mode.
Red channel selected, Green and Blue PGAs disabled.
1
0
01
1-channel (monochrome) mode.
Green channel selected, Red and Blue PGAs disabled.
1
0
10
1-channel (monochrome) mode.
Blue channel selected, Red and Green PGAs disabled.
X
X
11
Invalid mode
1
1
XX
Invalid mode
Table 14 Sampling Mode Summary
Note: Unused input pins should be connected to AGND unless reset level clamping is used.
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DEVICE CONFIGURATION
REGISTER MAP
The following table describes the location of each control bit used to determine the operation of the
WM8224.
ADDRES
S
DESCRIPTION
DEF
(hex)
R
W
BIT
b7
b6
b5
b4
ACLKDIV[0]
PGAFS[1]
b3
b2
b1
b0
<a5:a0>
000000 (00h) Device ID
82
000001 (01h) Setup Reg 1
03
RW ACLKDIV[1]
R
Reads first 2 digits of device part number
PGAFS[0]
TWOCHAN
MONO
CDS
EN
000010 (02h) Setup Reg 2
E8
RW
RES[1]
RES[0]
RLCDACRNG
LOWREFS
OPD
INVOP
AUTOZ
OPFORM
000011 (03h) Setup Reg 3
1F
RW
CHAN[1]
CHAN[0]
OEDEL[1]
OEDEL[0]
RLCDAC[3]
RLCDAC[2]
RLCDAC[1]
RLCCDAC[0]
000100 (04h) Software Reset
24
RW
Reads second 2 digits of device part number
000101 (05h) Device ID Revision
01
R
000110 (06h) Setup Reg 4
00
RW
OPDEL[3]
OPDEL[2]
OPDEL[1]
Reads revision number of device
OPDEL[0]
0
0
0
0
000111 (07h) Setup Reg 5
00
RW
0
0
ADCREFPD
VRLCDACPD
ADCPD
BLUPD
GRNPD
REDPD
FOL_EN
CLAMPCTRL
RLCEN
0
0
0
001000 (08h) Setup Reg 6
20
RW
0
0
001001 (09h) BLC Red Target
00
RW TARGETR[7] TARGETR[6] TARGETR[5] TARGETR[4] TARGETR[3] TARGETR[2]
TARGETR[1]
TARGETR[0]
001010 (0Ah) BLC Green Target
00
RW TARGETG[7] TARGETG[6] TARGETG[5] TARGETG[4] TARGETG[3] TARGETG[2]
TARGETG[1]
TARGETG[0]
001011 (0Bh) BLC Blue Target
00
RW TARGETB[7] TARGETB[6] TARGETB[5]
TARGETB[1]
TARGETB[0]
001100 (0Ch) BLC Control 1
00
RW STATE_OUT
0
0
0
FSCALE_RE
L
TG_REG
TG_METHOD
[1]
TG_METHOD
[0]
001101 (0Dh) BLC Control 2
00
RW
0
0
0
FA_EN
CADUR[2]
CADUR[1]
CADUR[0]
001110 (0Eh) BLC Control 3
00
RW BPIX_AVAIL BPIX_AVAIL
CA_
[9]
[8]
EVERYLINE
FA_
EVERYLINE
FA_ACCUM FRAME_SEQ
SEQ_START
FRAME_
START
001111 (Ofh) BLC Control 4
00
RW BPIX_AVAIL BPIX_AVAIL BPIX_AVAIL
[7]
[6]
[5]
BPIX_AVAIL
[4]
BPIX_AVAIL BPIX_AVAIL
[3]
[2]
BPIX_AVAIL
[1]
BPIX_AVAIL
[0]
0
TARGETB[4] TARGETB[3] TARGETB[2]
100000 (20h) DAC Value (Red)
80
RW
DACR[7]
DACR[6]
DACR[5]
DACR[4]
DACR[3]
DACR[2]
DACR[1]
DACR[0]
100001 (21h) DAC Value (Green)
80
RW
DACG[7]
DACG[6]
DACG[5]
DACG[4]
DACG[3]
DACG[2]
DACG[1]
DACG[0]
100010 (22h) DAC Value (Blue)
80
RW
DACB[7]
DACB[6]
DACB[5]
DACB[4]
DACB[3]
DACB[2]
DACB[1]
DACB[0]
100011 (23h) DAC Value (RGB)
80
W
DACRGB[7]
DACRGB[6]
DACRGB[5]
DACRGB[4]
DACRGB[3]
DACRGB[2]
DACRGB[1]
DACRGB[0]
100100 (24h) PGA Gain LSB (Red)
00
RW
0
0
0
0
0
0
0
PGAR[0]
100101 (25h) PGA Gain LSB (Green)
00
RW
0
0
0
0
0
0
0
PGAG[0]
100110 (26h) PGA Gain LSB (Blue)
00
RW
0
0
0
0
0
0
0
PGAB[0]
100111 (27h) PGA Gain LSB (RGB)
00
W
0
0
0
0
0
0
0
PGARGB[0]
101000 (28h) PGA Gain MSBs (Red)
0C
RW
PGAR[8]
PGAR[7]
PGAR[6]
PGAR[5]
PGAR[4]
PGAR[3]
PGAR[2]
PGAR[1]
101001 (29h) PGA Gain MSBs (Green)
0C
RW
PGAG[8]
PGAG[7]
PGAG[6]
PGAG[5]
PGAG[4]
PGAG[3]
PGAG[2]
PGAG[1]
101010 (2Ah) PGA Gain MSBs (Blue)
0C
RW
PGAB[8]
PGAB[7]
PGAB[6]
PGAB[5]
PGAB[4]
PGAB[3]
PGAB[2]
PGAB[1]
101011 (2Bh) PGA Gain MSBs (RGB)
0C
W
PGARGB[8]
PGARGB[7]
PGARGB[6]
PGARGB[5]
PGARGB[4]
PGARGB[3]
PGARGB[2]
PGARGB[1]
101100(2Ch) BLC Control 5
00
RW LINE_DEL[8] BLC_DEL[6]
BLC_DEL[5]
BLC_DEL[4]
BLC_DEL[3]
BLC_DEL[2]
BLC_DEL[1]
BLC_DEL[0]
101101(2Dh) BLC Control 6
00
RW LINE_DEL[7] LINE_DEL[6] LINE_DEL[5]
LINE_DEL[4] LINE_DEL[3] LINE_DEL[2]
LINE_DEL[1]
LINE_DEL[0]
Table 15 Register Map
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REGISTER MAP DESCRIPTION
The following table describes the function of each of the control bits shown in Table 15.
REGISTER
REGISTER
NAME
BIT
NO
R0 (00h)
Device ID
7:0
R1 (01h)
Setup
Register 1
0
BIT
NAME(S)
DEFAULT
10000010
EN
1
DESCRIPTION
Read only register. Reading from this register returns the
first 2 digits of device part number.
Global Enable
0 = complete power down,
1 = fully active (individual blocks can be disabled using
individual powerdown bits – see setup register 5).
1
CDS
1
Select correlated double sampling mode:
0 = non-CDS mode,
1 = CDS mode.
2
MONO
0
Sampling mode select
0 = other mode (2 or 3-channel)
1 = Monochrome (1-channel) mode. Input channel
selected by CHAN[1:0] register bits, unused channel is
powered down.
TWOCHAN and MONO should not be set concurrently.
3
TWOCHAN
0
Sampling mode select
0 = other mode (1 or 3-channel)
1 = 2-channel mode.
TWOCHAN and MONO should not be set concurrently.
5:4
PGAFS[1:0]
00
Offsets PGA output to optimise the ADC range for different
polarity sensor output signals. Zero differential PGA input
signal gives:
0x = Zero output from the PGA (Output code=511)
10 = Full-scale positive output (OP=1023) – use for
negative going video.
NB, Set INVOP=1 if zero differential input
should give a zero output code with negative
going video.
11 = Full-scale negative output (OP=0) - use for positive
going video
7:6
ACLKDIV[1:0]
00
Reduces the internal clock frequency to allow analogue
circuitry to run at a slower rate when daisy chaining
devices.
00 – no divide
01 – divide MCLK by 2 internally
10 – divide MCLK by 3 internally
11 – not valid
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REGISTER
R2 (02h)
Production Data
REGISTER
NAME
Setup
Register 2
BIT
NO
BIT
NAME(S)
DEFAULT
0
OPFORM
0
DESCRIPTION
Output format :
0 = Multiplexed mode
1 = Parallel mode
1
AUTOZ
0
When set the output goes to high impedance other than
during valid data output. This will override the OEB/OPD
control.
0 = Output pins high impedance mode controlled by
OPD/OEB
1 = Output pins high impedance mode controlled
automatically. Normally used in multiple device mode
where several devices share a common data bus.
AUTOZ should not be set if MCLK:VSMP is 1:1.
2
INVOP
0
Digitally inverts the polarity of output data.
0 = negative going video gives negative going output,
1 = negative-going video gives positive going output data.
3
OPD
1
Output Disable. This works with the OEB pin to control the
output pins.
This is only valid if AUTOZ=0.
0=Digital outputs enabled, 1=Digital outputs high
impedance
4
LOWREFS
0
OEB (pin)
OPD
OP pins
0
0
Enabled
0
1
High Impedance
1
0
High Impedance
1
1
High impedance
Reduces the ADC reference range (2*[VRT-VRB]), thus
changing the max/min input video voltages (ADC ref
range/PGA gain).
0= ADC reference range = 2.0V
1= ADC reference range = 1.2V
5
RLCDACRNG
1
Sets the output range of the RLCDAC.
0 = RLCDAC ranges from 0 to AVDD (approximately),
1 = RLCDAC ranges from 0 to VRT (approximately).
7:6
R3 (03h)
Setup
Register 3
RES[1:0]
11
3:0
RLCDAC[3:0]
1111
5:4
OEDEL[1:0]
01
Controls the device output resolution:
RES
Output Resolution
00
8-bit
01
10-bit
10
12-bit
11
16-bit
Controls RLCDAC driving VRLC/VBIAS pin to define
single ended signal reference voltage or Reset Level
Clamp voltage. See Electrical Characteristics section for
ranges.
Adjustable delay for beginning of automatic OE signal.
Only valid when AUTOZ=1
00 : typically adds 0.5ns to tPD time
01 : typically adds 1.0ns to tPD time
10 : typically adds 1.5ns to tPD time
11 : typically adds 2.0ns to tPD time
7:6
CHAN[1:0]
00
When MONO=0 and TWOCHAN=0 this register bit has no
effect
When MONO=1:
00 = Red channel select
01 = Green channel select
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10 = Blue
channel select
11 = Reserved
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REGISTER
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REGISTER
NAME
BIT
NO
BIT
NAME(S)
DEFAULT
DESCRIPTION
When TWOCHAN=1:
00 = Red PGA disabled (G&B only)
01 = Green PGA disabled (R&B only)
R4 (04h)
Software
Reset
7:0
00100100
10 = Blue PGA
disabled (R&G
only)
11 = Reserved
Any write to Software Reset causes all register bits to be
reset. It is recommended that a software reset be
performed after a power-up before any other register
writes.
Reading from this register returns the last 2 digits of the
device part number.
R5 (05h)
Device ID
Revision
7:0
R6 (06h)
Setup
Register 4
3:0
Reserved
0000
Must be set to 0000
7:4
OPDEL[3:0]
000
Output latency adjust (ACLKDIV=00).
00000001
Reading from this register returns the revision number of
the device.
0000 = Minimum latency (7 MCLK periods)
0001 = 8 MCLK periods
0010 = 9 MCLK periods
0011 = 10 MCLK periods
0100 = 11 MCLK periods
0101 = 12 MCLK periods
0110 = 13 MCLK periods
0111 = 14 MCLK periods
1000 = 15 MCLK periods
1001 to 1111 = Invalid settings
R7 (07h)
Setup
Register 5
0
REDPD
0
1
GRNPD
0
When set powers down green S/H, PGA
2
BLUPD
0
When set powers down blue S/H, PGA
3
ADCPD
0
When set powers down red S/H, PGA
When set powers down ADC. Allows reduced power
consumption without powering down the references which
have a long time constant when switching on/off due to the
external decoupling capacitors.
4
VRLCDACPD
0
When set powers down 4-bit RLCDAC, setting the output
to a high impedance state and allowing an external
reference to be driven in on the VRLC/VBIAS pin.
5
ADCREFPD
0
When set disables VRT, VRB buffers to allow external
references to be used.
R8 (08h)
Setup
Register 6
7:6
Reserved
00
4:0
5
Reserved
RLCEN
00000
1
6
CLAMPCTRL
0
Must be set to 00
Must be set to 0
Reset Level Clamp Enable. When set Reset Level
Clamping is enabled. The method of clamping is
determined by CLAMPCTRL.
0 = RLC switch is controlled directly from RSMP input pin:
RSMP = 0: switch is open
RMSP = 1: switch is closed
1 = RLC switch is controlled by logical combination of
RSMP and VSMP.
RSMP && VSMP = 0: switch is open
Switch is re-opened when:
VSMP=0 (non-CDS mode)
VSMP=0 and RSMP=0 (CDS mode)
7
FOL_EN
0
Enables internal input voltage buffers, to minimise code
drift if not pixel clamping, when using an ac coupling
capacitor in non-CDS mode (CDS=0).
Line clamping should be used when this bit is set.
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WM8224
REGISTER
Production Data
REGISTER
NAME
BIT
NO
BIT
NAME(S)
DEFAULT
DESCRIPTION
Target Black-Level code for Red channel. Please see the
R9 (09h)
BLC Red
Target
7:0
TARGETR
[7:0]
00000000
R10 (0Ah)
BLC Green
Target
7:0
TARGETG
[7:0]
00000000
R11 (0Bh)
BLC Blue
Target
7:2
TARGETB
[7:0]
00000000
R12 (0Ch)
BLC Control
1
1:0
TG_METHOD
00
Target Codes Section for details.
Target Black-Level code for Green channel. Please see
the Target Codes Section for details.
Target Black-Level code for Blue channel. Please see the
Target Codes Section for details.
Determines the start-of-line method to be used.
00 = TG_REG method
[1:0]
01 = Not a valid option
10 = OEB/TG shared pin method, +ve edge triggered
11 = OEB/TG shared pin method, -ve edge triggered
2
TG_REG
0
Register flag to indicate a start-of-line, this register is
automatically set to zero after it has been clocked by the
BLC.
R13 (0Dh)
R14 (0Eh)
BLC Control
2
BLC Control
3
3
FSCALE_
REL
0
Inverts the Black-level target codes so they are relative to
4
RESERVED
0
Set to zero
6:5
RESERVED
00
Set to zero
7
STATE_OUT
0
Outputs the 2-bit state of the BLC onto OP0 and OP1.
2:0
CADUR[2:0]
000
Controls the number of Coarse Adjust iterations to be
3
FA_EN
0
7:4
RESERVED
0000
0
FRAME_
START
0
SEQ_START
0
fullscale.
performed.
Enables the Fine Adjust operation
Set to zero
Register to indicate that the next start-of-line indicator is
the first line in a frame. This register is automatically set
to zero at the end of the BLC operation on the first line.
1
Register to indicate that the next start-of-line indicator is
the first line of the first frame in a frame-sequence. This
register is automatically set to zero at the end of the BLC
operation on the first line.
2
FRAME_SEQ
0
Indicates that the BLC is to be used in a sequence of
3
FA_ACCUM
0
Makes the Fine Adjust calibration accumulate a result over
4
FA_
EVERYLINE
0
multiple lines.
st
0 = Fine Adjust only used on the 1 line of a frame
5
CA_
EVERYLINE
0
1 = Fine Adjust used on every line of a frame
st
0 = Coarse Adjust only used on the 1 line of a frame
7:6
BPIX_AVAIL
[9:8]
00
MSBs of the number of Black-pixels available over which
frames
1 = Coarse Adjust used on every line of a frame
to perform the Coarse and/or Fine Adjust Calibration.
R15 (0Fh)
BLC Control
4
7:0
BPIX_AVAIL
[7:0]
00000000
LSBs of the number of Black-pixels available over which to
R32 (20h)
Offset DAC
(Red)
7:0
DACR[7:0]
10000000
perform the Coarse and/or Fine Adjust Calibration.
Red channel 8-bit offset DAC value (mV) =
250*(DACR[7:0]-127.5)/127.5
R33 (21h)
Offset DAC
(Green)
7:0
DACG[7:0]
10000000
Green channel 8-bit offset DAC value (mV) =
250*(DACG[7:0]-127.5)/127.5
R34 (22h)
Offset DAC
(Blue)
7:0
DACB[7:0]
10000000
Blue channel 8-bit offset DAC value (mV) =
250*(DACB[7:0]-127.5)/127.5
Offset DAC
7:0
DACRGB[7:0]
-
A write to this register location causes the red, green and
blue offset DAC registers to be overwritten by the new
value
0
PGAR[0]
0
This register bit forms the LSB of the red channel PGA
gain code. PGA gain is determined by combining this
register bit and the 8 MSBs contained in register address
28 hex.
R35 (23h)
(RGB)
R36 (24h)
PGA Gain
LSB
(Red)
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WM8224
REGISTER
R37 (25h)
Production Data
REGISTER
NAME
PGA Gain
BIT
NO
BIT
NAME(S)
DEFAULT
0
PGAG[0]
0
This register bit forms the LSB of the green channel PGA
gain code. PGA gain is determined by combining this
register bit and the 8 MSBs contained in register address
29 hex.
0
PGAB[0]
0
This register bit forms the LSB of the blue channel PGA
LSB
(Green)
R38 (26h)
PGA Gain
DESCRIPTION
LSB
gain code. PGA gain is determined by combining this
(Blue)
register bit and the 8 MSBs contained in register address
2A hex.
R39 (27h)
PGA Gain
0
PGARGB[0]
-
LSB
R40 (28h)
(RGB)
PGA gain
MSBs
Writing a value to this location causes red, green and blue
PGA LSB gain values to be overwritten by the new value.
7:0
PGAR[8:1]
00001100
(Red)
Bits 8 to 1 of red PGA gain. Combined with red LSB
register bit to form complete PGA gain code. This
determines the gain of the red channel PGA according to
the equation:
Red channel PGA gain (V/V) = 0.66 +
PGAR[8:0]x7.34/511
R41 (29h)
PGA gain
MSBs
(Green)
7:0
PGAG[8:1]
00001100
Bits 8 to 1 of green PGA gain. Combined with green LSB
register bit to form complete PGA gain code. This
determines the gain of the green channel PGA according
to the equation:
Green channel PGA gain (V/V) = 0.66 +
PGAG[8:0]x7.34/511
R42 (2Ah)
PGA gain
MSBs
7:0
PGAB[8:1]
00001100
(Blue)
Bits 8 to 1 of blue PGA gain. Combined with blue LSB
register bit to form complete PGA gain code. This
determines the gain of the blue channel PGA according to
the equation:
Blue channel PGA gain (V/V) = 0.66 +
PGAB[8:0]x7.34/511
R43 (2Bh)
PGA gain
MSBs
7:0
PGARGB[8:1]
-
6:0
BLC_DEL
0000000
(RGB)
R44 (2Ch)
BLC Control
5
[6:0]
7
LINE_DEL
BLC Control
6
7:0
LINE_DEL
[7:0]
Determines the number of pixels (from the start of a line)
to delay the start of a BLC operation.
0
MSB of the number of lines from the start of a frame to
delay the start of a BLC operation.
00000000
LSBs of the number of lines from the start of a frame to
delay the start of a BLC operation.
[8]
R45 (2Dh)
A write to this register location causes the red, green and
blue PGA MSB gain registers to be overwritten by the new
value.
Table 16 Register Control Bits
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WM8224
Production Data
APPLICATIONS INFORMATION
RECOMMENDED EXTERNAL COMPONENTS
Figure 39 External Components Diagram
RECOMMENDED EXTERNAL COMPONENT VALUES
COMPONENT
REFERENCE
SUGGESTED
VALUE
DESCRIPTION
C1
100nF
De-coupling for DVDD
C2
100nF
De-coupling for AVDD
C3
1F
C4
100nF
Ceramic de-coupling between VRT and VRB (non polarized)
C5
100nF
De-coupling for VRX
C6
100nF
De-coupling for VRT
C7
100nF
De-coupling for VRLC
C8
10F
Reservoir capacitor for DVDD
C9
10F
Reservoir capacitor for AVDD
De-coupling for VRB
Table 17 External Components Descriptions
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WM8224
Production Data
PACKAGE DIMENSIONS
FL: 32 PIN QFN PLASTIC PACKAGE 5 X 5 X 0.9 mm BODY, 0.50 mm LEAD PITCH
DM101.A
D
DETAIL 1
D2
32
25
L
1
24
4
EXPOSED
GROUND 6
PADDLE
INDEX AREA
(D/2 X E/2)
E2
17
E
8
16
2X
15
9
b
B
e
1
bbb M C A B
2X
aaa C
aaa C
TOP VIEW
BOTTOM VIEW
ccc C
A3
A
5
0.08 C
C
A1
SIDE VIEW
SEATING PLANE
M
M
45°
DETAIL 2
0.30
EXPOSED
GROUND
PADDLE
DETAIL 1
W
Exposed lead
T
A3
G
H
b
Half etch tie bar
DETAIL 2
Symbols
A
A1
A3
b
D
D2
E
E2
e
G
H
L
T
W
MIN
0.80
0
0.18
3.30
3.30
0.30
Dimensions (mm)
NOM
MAX
NOTE
0.90
1.00
0.02
0.05
0.203 REF
1
0.25
0.30
5.00 BSC
3.45
5.00 BSC
3.45
0.50 BSC
0.20
0.1
0.40
0.103
3.60
2
3.60
2
0.50
0.15
Tolerances of Form and Position
aaa
bbb
ccc
REF:
0.15
0.10
0.10
JEDEC, MO-220, VARIATION VHHD-5.
NOTES:
1. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.15 mm AND 0.30 mm FROM TERMINAL TIP.
2. FALLS WITHIN JEDEC, MO-220, VARIATION VHHD-5.
3. ALL DIMENSIONS ARE IN MILLIMETRES.
4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JEDEC 95-1 SPP-002.
5. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS.
6. REFER TO APPLICATION NOTE WAN_0118 FOR FURTHER INFORMATION REGARDING PCB FOOTPRINTS AND QFN PACKAGE SOLDERING.
7. THIS DRAWING IS SUBJECT TO CHANGE WITHOUT NOTICE.
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WM8224
Production Data
IMPORTANT NOTICE
Wolfson Microelectronics plc (“Wolfson”) products and services are sold subject to Wolfson’s terms and conditions of sale,
delivery and payment supplied at the time of order acknowledgement.
Wolfson warrants performance of its products to the specifications in effect at the date of shipment. Wolfson reserves the
right to make changes to its products and specifications or to discontinue any product or service without notice. Customers
should therefore obtain the latest version of relevant information from Wolfson to verify that the information is current.
Testing and other quality control techniques are utilised to the extent Wolfson deems necessary to support its warranty.
Specific testing of all parameters of each device is not necessarily performed unless required by law or regulation.
In order to minimise risks associated with customer applications, the customer must use adequate design and operating
safeguards to minimise inherent or procedural hazards. Wolfson is not liable for applications assistance or customer
product design. The customer is solely responsible for its selection and use of Wolfson products. Wolfson is not liable for
such selection or use nor for use of any circuitry other than circuitry entirely embodied in a Wolfson product.
Wolfson’s products are not intended for use in life support systems, appliances, nuclear systems or systems where
malfunction can reasonably be expected to result in personal injury, death or severe property or environmental damage.
Any use of products by the customer for such purposes is at the customer’s own risk.
Wolfson does not grant any licence (express or implied) under any patent right, copyright, mask work right or other
intellectual property right of Wolfson covering or relating to any combination, machine, or process in which its products or
services might be or are used. Any provision or publication of any third party’s products or services does not constitute
Wolfson’s approval, licence, warranty or endorsement thereof. Any third party trade marks contained in this document
belong to the respective third party owner.
Reproduction of information from Wolfson datasheets is permissible only if reproduction is without alteration and is
accompanied by all associated copyright, proprietary and other notices (including this notice) and conditions. Wolfson is
not liable for any unauthorised alteration of such information or for any reliance placed thereon.
Any representations made, warranties given, and/or liabilities accepted by any person which differ from those contained in
this datasheet or in Wolfson’s standard terms and conditions of sale, delivery and payment are made, given and/or
accepted at that person’s own risk. Wolfson is not liable for any such representations, warranties or liabilities or for any
reliance placed thereon by any person.
ADDRESS:
Wolfson Microelectronics plc
Westfield House
26 Westfield Road
Edinburgh
EH11 2QB
Tel :: +44 (0)131 272 7000
Fax :: +44 (0)131 272 7001
Email :: [email protected]
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WM8224
Production Data
REVISION HISTORY
DATE
REV
ORIGINATOR
CHANGES
15/05/12
4.1
JMacD
Order codes updated from WM8224SEFL and WM8224SEFL/R to
WM8224CSEFL and WM8224CSEFL/R to reflect change to copper wire
bonding.
15/05/12
4.1
JMacD
Package Diagram updated to DM101.A
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