AD AD9882A/PCB

Dual Interface for
Flat Panel Displays
AD9882A
FUNCTIONAL BLOCK DIAGRAM
APPLICATIONS
RGB graphics processing
LCD monitors and projectors
Plasma display panels
Scan converter
Microdisplays
Digital TV
AD9882A
ANALOG INTERFACE
REF
RAIN
CLAMP
A/D
GAIN
CLAMP
A/D
BAIN
CLAMP
A/D
SOGIN
HSYNC
FILT
VSYNC
SCL
SDA
A0
SYNC
PROCESSING AND
CLOCK
GENERATION
8
ROUT
8
GOUT
8
BOUT
8
DATACK
HSOUT
VSOUT
SOGOUT
8
8
SERIAL REGISTER AND
POWER MANAGEMENT
DVI
RECEIVER
ROUT
GOUT
BOUT
DATACK
HSOUT
CSOUT
DIGITAL INTERFACE
RX0+
RX0–
RX1+
RX1–
RX2+
RX2–
RXC+
RXC–
RTERM
DDCSCL
DDCSDA
MCL
MDA
REFBYPASS
MUXES
Analog interface
140 MSPS maximum conversion rate
Programmable analog bandwidth
0.5 V to 1.0 V analog input range
500 ps p-p PLL clock jitter at 140 MSPS
3.3 V power supply
Full sync processing
Midscale clamping
4:2:2 output format mode
Digital interface
DVI 1.0 compatible interface
112 MHz operation
High skew tolerance of 1 full input clock
Sync detect for hot plugging
Supports high bandwidth digital content protection
8
ROUT
8
GOUT
8
BOUT
SOGOUT
DE
DATACK
DE
HSYNC
HDCP
VSYNC
05123-001
FEATURES
Figure 1.
GENERAL DESCRIPTION
The AD9882A offers designers the flexibility of an analog interface and a digital visual interface (DVI) receiver integrated on a
single chip. Also included is support for high bandwidth digital
content protection (HDCP).
Analog Interface
The AD9882A is a complete, 8-bit, 140 MSPS monolithic
analog interface optimized for capturing RGB graphics signals
from personal computers and workstations. Its 140 MSPS
encode rate capability and full power analog bandwidth of 300
MHz sup-ports resolutions up to SXGA (1280 × 1024 at 75 Hz).
The analog interface includes a 140 MHz triple ADC with
internal 1.25 V reference, a phase-locked loop (PLL), programmable gain, offset, and clamp control. The user provides only a
3.3 V power supply, analog input, and Hsync. Three-state
CMOS outputs can be powered from 2.2 V to 3.3 V.
The AD9882A’s on-chip PLL generates a pixel clock from
Hsync. Pixel clock output frequencies range from 12 MHz to
140 MHz. PLL clock jitter is typically 500 ps p-p at 140 MSPS.
The AD9882A also offers full sync processing for composite
sync and sync-on-green (SOG) applications.
Digital Interface
The AD9882A contains a DVI 1.0 compatible receiver and
supports display resolutions up to SXGA (1280 × 1024 at
60 Hz). The receiver features an intrapair skew tolerance of up
to one full clock cycle.
With the inclusion of HDCP, displays can now receive
encrypted video content. The AD9882A allows for authentication of a video receiver, decryption of encoded data at the
receiver, and renewability of that authentication during transmission, as specified by the HDCP v1.0 protocol. It also has
high tolerance of noncompliant HDCP sources.
Fabricated in an advanced CMOS process, the AD9882A is
provided in a space-saving, 100-lead LQFP surface-mount
plastic package and is specified over the 0°C to 70°C
temperature range. It is available in a Pb-free package.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.326.8703
© 2004 Analog Devices, Inc. All rights reserved.
AD9882A
TABLE OF CONTENTS
Specifications............................................................................................3
Special Characters .............................................................................20
Absolute Maximum Ratings ..................................................................6
Channel Resynchronization.............................................................20
Explanation of Test Levels..................................................................6
Data Decoder .....................................................................................20
ESD Caution ........................................................................................6
HDCP..................................................................................................20
Pin Configuration and Function Descriptions....................................7
General Timing Diagrams: Digital Interface.................................22
Pin Descriptions of Shared Pins between Analog and Digital
Interfaces ..............................................................................................8
Timing Mode Diagrams: Digital Interface ....................................22
Serial Port (2-Wire) ............................................................................8
Data Outputs........................................................................................8
Pin Function Detail: Analog Interface .............................................9
Power Supply .....................................................................................10
Theory of Operation: Interface Detection .........................................12
Active Interface Detection and Selection.......................................12
Power Management ..........................................................................12
Theory of Operation and Design Guide: Analog Interface.............13
General Description..........................................................................13
Input Signal Handling ......................................................................13
Hsync and Vsync Inputs ..................................................................13
Serial Control Port ............................................................................13
Output Signal Handling ...................................................................13
Clamping ............................................................................................13
Gain and Offset Control...................................................................14
Sync-on-Green (SOG)......................................................................15
Clock Generation ..............................................................................15
Timing: Analog Interface .....................................................................17
Timing Diagrams ..............................................................................18
Theory of Operation: Digital Interface...............................................19
Digital Interface Pin Descriptions ..................................................19
2-Wire Serial Register Map ..................................................................23
2-Wire Serial Control Register Detail.................................................26
Chip Identification ............................................................................26
PLL Divider Control .........................................................................26
Clamp Timing....................................................................................27
Hsync Output Pulse Width..............................................................27
Input Gain ..........................................................................................27
Input Offset ........................................................................................27
2-Wire Serial Control Port...............................................................32
Sync Processing Engine ........................................................................35
Sync Slicer...........................................................................................35
Sync Separator ...................................................................................35
PCB Layout Recommendations...........................................................36
Analog Interface Inputs ....................................................................36
Digital Interface Inputs.....................................................................36
Power Supply Bypassing ...................................................................36
PLL ......................................................................................................37
Outputs: Data and Clocks ................................................................37
Digital Inputs .....................................................................................37
Voltage Reference ..............................................................................37
Outline Dimensions ..............................................................................38
Ordering Guide..................................................................................38
Capturing the Encoded Data...........................................................20
Data Frames .......................................................................................20
REVISION HISTORY
10/04—Revision 0: Initial Version
Rev. 0 | Page 2 of 40
AD9882A
SPECIFICATIONS
VD = 3.3 V, VDD = 3.3 V, ADC clock = maximum conversion rate, unless otherwise noted.
Table 1. Analog Interface Electrical Characteristics
Parameter
RESOLUTION
DC ACCURACY
Differential Nonlinearity
Integral Nonlinearity
No Missing Codes
ANALOG INPUT
Input Voltage Range
Minimum
Maximum
Gain Tempco
Input Bias Current
Input Full-Scale Matching
Offset Adjustment Range
REFERENCE OUTPUT
Output Voltage
Temperature Coefficient
SWITCHING PERFORMANCE1
Maximum Conversion Rate
Minimum Conversion Rate
Clock to Data Skew, tSKEW
Serial Port Timing
tBUFF
tSTAH
tDHO
tDAL
tDAH
tDSU
tSTASU
tSTOSU
Hsync Input Frequency
Maximum PLL Clock Rate
Minimum PLL Clock Rate
PLL Jitter
Sampling Phase Tempco
DIGITAL INPUTS
Input Voltage, High (VIH)
Input Voltage, Low (VIL)
Input Current, High (IIH)
Input Current, Low (IIL)
Input Capacitance
DIGITAL OUTPUTS
Output Voltage, High (VOH)
Output Voltage, Low (VOL)
Duty Cycle, DATACK
Min
AD9882AKSTZ-100
Typ
Max
8
Temp
Test Level
25°C
Full
25°C
Full
Full
I
VI
I
VI
VI
Full
Full
25°C
Full
Full
Full
VI
VI
V
IV
VI
VI
Full
Full
VI
V
Full
Full
Full
VI
IV
IV
Full
Full
Full
Full
Full
Full
Full
Full
Full
Full
Full
25°C
Full
Full
VI
VI
VI
VI
VI
VI
VI
VI
IV
VI
IV
IV
IV
IV
4.7
4.0
250
4.7
4.0
250
4.7
4.0
15
100
Full
Full
Full
Full
25°C
VI
VI
IV
IV
V
2.6
Full
Full
Full
IV
IV
IV
VDD – 0.1
Min
AD9882AKSTZ-140
Typ
Max
8
±0.5
+1.25/–1.0
+1.35/–1.0
±0.5 ±1.85
±2.0
Guaranteed
±0.5
+1.35/–1.0
+1.45/–1.0
±0.5 ±2.0
±2.3
Guaranteed
0.5
0.5
1.0
45
1.5
49
100
1
8.0
56
45
1.25
±50
1.5
49
1
8.0
56
1.25
±50
100
V
ppm/°C
140
10
+2.0
–0.5
4.7
4.0
250
4.7
4.0
250
4.7
4.0
15
140
110
500
12
7002
1000
110
500
2
15
12
700
1000
2
15
2.6
0.8
–1.0
1.0
0.8
–1.0
1.0
3
MSPS
MSPS
ns
10
+2.0
–0.5
LSB
LSB
LSB
LSB
V p-p
V p-p
ppm/°C
µA
% FS
% FS
1.0
100
Unit
Bits
3
2
µs
µs
ns
µs
µs
ns
µs
µs
kHz
MHz
MHz
ps p-p
ps p-p
ps/°C
V
V
µA
µA
pF
1
45
VDD – 0.1
50
Rev. 0 | Page 3 of 40
0.4
55
45
50
0.4
55
V
V
%
AD9882A
Parameter
Output Coding
POWER SUPPLY
VD Supply Voltage
VDD Supply Voltage
PVD Supply Voltage
ID Supply Current (VD)
IDD Supply Current (VDD)3
IPVD Supply Current (PVD)
Total Supply Current
Power-Down Supply Current
DYNAMIC PERFORMANCE
Analog Bandwidth, Full Power
Signal-to-Noise Ratio (SNR)
fIN = 2.3 MHz
Crosstalk
THERMAL CHARACTERISTICS
θJA Junction-to-Ambient4
AD9882AKSTZ-100
Typ
Max
Binary
Min
AD9882AKSTZ-140
Typ
Max
Binary
Temp
Test Level
Min
Unit
Full
Full
Full
25°C
25°C
25°C
Full
Full
IV
IV
IV
V
V
V
VI
VI
3.15
2.2
3.15
25°C
25°C
V
V
300
44
300
43
MHz
dB
Full
V
55
55
dBc
V
43
43
°C/W
1
3.3
3.3
3.3
162
47
19
228
30
3.45
3.45
3.45
3.15
2.2
3.15
3.3
3.3
3.3
181
63
21
265
30
237
35
3.45
3.45
3.45
V
V
V
mA
mA
mA
mA
mA
274
35
1
Drive strength = 11.
VCO range = 10, Charge pump current = 110, PLL divider = 1693.
DATACK Load = 15 pF, Data load = 5 pF.
4
Simulated typical performance with package mounted to a 4-layer board.
2
3
VD = 3.3 V, VDD = 3.3 V, clock = maximum, unless otherwise noted.
Table 2. Digital Interface Electrical Characteristics
Parameter
RESOLUTION
DC DIGITAL I/O Specifications
High Level Input Voltage (VIH)
Low Level Input Voltage (VIL)
High Level Output Voltage (VOH)
Low Level Output Voltage (VOL)
Output Leakage Current (IOL)
DC SPECIFICATIONS
Output High Drive
(IOHD)(VOUT = VOH)
Output Low Drive
(IOLD)(VOUT = VOL)
DATACK High Drive
(VOHC)(VOUT = VOH)
DATACK Low Drive
(VOLC)(VOUT = VOL)
Conditions
Temp
Test Level
High impedance
Full
Full
Full
Full
Full
VI
VI
IV
IV
IV
Output drive = high
Output drive = medium
Output drive = low
Output drive = high
Output drive = medium
Output drive = low
Output drive = high
Output drive = medium
Output drive = low
Output drive = high
Output drive = medium
Output drive = low
Full
Full
Full
Full
Full
Full
Full
Full
Full
Full
Full
Full
V
V
V
V
V
V
V
V
V
V
V
V
Full
IV
Differential Input Voltage
Single-Ended Amplitude
Rev. 0 | Page 4 of 40
AD9882AKSTZ
Min Typ Max
8
2.6
0.8
2.4
0.4
+10
–10
11
8
5
–7
–6
–5
28
14
7
–15
–9
–7
75
Unit
Bits
V
V
V
V
µA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
800
mV
AD9882A
Parameter
POWER SUPPLY
VD Supply Voltage
VDD Supply Voltage
PVD Supply Voltage
ID Supply Current (Typical Pattern)1
IDD Supply Current (Typical Pattern)1, 2
IPVD Supply Current (Typical Pattern) 1
Total Supply Current with HDCP
(Typical Pattern) 1, 2
ID Supply Current (Worst-Case Pattern)3
IDD Supply Current
(Worst-Case Pattern) 2, 3
IPVD Supply Current
(Worst-Case Pattern) 3
Total Supply Current with HDCP
(Worst-Case Pattern) 2, 3
Power-Down Supply Current (IPD)
AC SPECIFICATIONS
Intrapair (+ to –) Differential Input
Skew (TDPS)
Channel-to-Channel Differential
Input Skew (TCCS)
Low-to-High Transition Time
for Data (DLHT)
Low-to-High Transition Time
for DATACK (DLHT)
High-to-Low Transition Time
for Data (DHLT)
High-to-Low Transition Time
for DATACK (DHLT)
Conditions
AD9882AKSTZ
Min Typ Max
Temp
Test Level
Full
Full
Full
25°C
25°C
25°C
Full
IV
IV
IV
V
V
V
IV
25°C
25°C
V
V
247
61
mA
mA
25°C
V
57
mA
Full
IV
385
420
mA
Full
VI
30
35
mA
Full
IV
360
ps
Full
IV
1
Clock Period
Output drive = high, CL = 10 pF
Full
IV
2.2
ns
Output drive = medium,
CL = 7 pF
Output drive = low, CL = 5 pF
Output drive = high, CL = 10 pF
Full
Full
Full
IV
IV
IV
2.5
3.2
1.0
ns
ns
ns
Output drive = medium,
CL = 7 pF
Output drive = low, CL = 5 pF
Output drive = high, CL = 10 pF
Full
Full
Full
IV
IV
IV
1.6
2.1
2.2
ns
ns
ns
Full
Full
Full
IV
IV
IV
1.9
1.7
1.0
ns
ns
ns
Full
Full
Full
Full
Full
IV
IV
IV
IV
VI
1.0
1.4
+2.0
50
112
ns
ns
ns
%
MHz
Output drive = medium,
CL = 7 pF
Output drive = low, CL = 5 pF
Output drive = high,
CL = 10 pF
Output drive = medium,
CL = 7 pF
Output drive = low, CL = 5 pF
Clock -to- Data Skew,4 tSKEW
Duty Cycle, DATACK
DATACK Frequency (FCIP)
4
1
The typical pattern contains a gray scale area. Output drive = high.
DATACK load = 10 pF, data load = 10 pF.
The worst-case pattern contains a black and white checkerboard pattern. Output drive = high.
4
Drive strength = 11.
2
3
Rev. 0 | Page 5 of 40
3.15
2.2
3.15
–0.5
40
25
3.3
3.3
3.3
237
25
57
340
46
3.45
3.45
3.45
367
Unit
V
V
V
mA
mA
mA
mA
AD9882A
ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter
VD
VDD
Analog Inputs
VREF
Digital Inputs
Digital Output Current
Operating Temperature
Storage Temperature
Maximum Junction Temperature
Maximum Case Temperature
EXPLANATION OF TEST LEVELS
Rating
3.6 V
3.6 V
VD to 0.0 V
VD to 0.0 V
5 V to 0.0 V
20 mA
–25°C to +85°C
–65°C to +150°C
150°C
150°C
I. 100% production tested.
II. 100% production tested at 25°C and sample tested at
specified temperatures.
III. Sample tested only.
IV. Parameter is guaranteed by design and characterization
testing.
V. Parameter is a typical value only.
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating; functional operation of the device at these or any other
conditions outside of those indicated in the operation sections
of this specification is not implied. Exposure to absolute
maximum ratings for extended periods may affect device
reliability.
VI. 100% production tested at 25°C; guaranteed by design and
characterization testing.
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although
this product features proprietary ESD protection circuitry, permanent damage may occur on devices
subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are
recommended to avoid performance degradation or loss of functionality.
Rev. 0 | Page 6 of 40
AD9882A
GND
1
GREEN<7>
2
GREEN<6>
76 A0
77 SCL
78 SDA
79 HSYNC
80 VSYNC
81 MCL
82 MDA
83 VDD
84 GND
85 DATACK
86 DE
87 VSOUT
88 HSOUT
89 SOGOUT
90 VDD
91 GND
92 RED<7>
93 RED<6>
94 RED<5>
95 RED<4>
96 RED<3>
97 RED<2>
98 RED<1>
99 RED<0>
100 VDD
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
GND
74
MIDBYPASS
3
73
REFBYPASS
GREEN<5>
4
72
VD
GREEN<4>
5
71
GND
GREEN<3>
6
70
RAIN
GREEN<2>
7
69
VD
GREEN<1>
8
68
GND
GREEN<0>
9
67
VD
VDD 10
66
GND
65
GAIN
64
SOGIN
63
VD
BLUE<5> 14
62
GND
BLUE<4> 15
61
VD
BLUE<3> 16
60
GND
BLUE<2> 17
59
BAIN
BLUE<1> 18
58
VD
BLUE<0> 19
57
GND
VDD 20
56
VD
GND 21
55
GND
CTL 0 22
54
DDCSDA
CTL 1 23
53
DDCSCL
CTL 2 24
52
PVD
CTL 3 25
51
GND
GND 11
AD9882A
BLUE<7> 12
GND 50
PVD 49
FILT 48
GND 47
PVD 46
GND 45
PVD 44
VD 43
RXC– 42
RXC+ 41
GND 40
RX2+ 39
RX2– 38
GND 37
RX1– 35
GND 34
RX0+ 33
RX0– 32
GND 31
VD 30
VD 29
RTERM 28
VD 27
GND 26
BLUE<6> 13
RX1+ 36
TOP VIEW
(Not to Scale)
05123-002
75
PIN 1
INDICATOR
Figure 2. 100-Lead LQFP Pin Configuration
Table 4. Pin Function Descriptions
Pin Type
Analog Video Inputs
External Sync/Clock
Sync Outputs
References
PLL Filter
Power Supply
Serial Port Control
Mnemonic
RAIN
GAIN
BAIN
HSYNC
VSYNC
SOGIN
HSOUT
VSOUT
SOGOUT
REFBYPASS
MIDBYPASS
FILT
VD
VDD
PVD
GND
SDA
SCL
A0
Function
Analog Input for Converter R
Analog Input for Converter G
Analog Input for Converter B
Horizontal Sync Input
Vertical Sync Input
Input for Sync-on-Green
HSYNC Output Clock (Phase-Aligned with
DATACK)
VSYNC Output Clock
Sync-on-Green Slicer Output
Internal Reference Bypass
Internal Midscale Voltage Bypass
Connection for External Filter Components for
Internal PLL
Analog Power Supply
Output Power Supply
PLL Power Supply
Ground
Serial Port Data I/O
Serial Port Data Clock (100 kHz Maximum)
Serial Port Address Input
Rev. 0 | Page 7 of 40
Value
0.0 V to 1.0 V
0.0 V to 1.0 V
0.0 V to 1.0 V
3.3 V CMOS
3.3 V CMOS
0.0 V to 1.0 V
3.3 V CMOS
3.3 V CMOS
3.3 V CMOS
1.25 V
3.15 V to 3.45 V
2.2 V to 3.6 V
3.15 V to 3.45 V
0V
3.3 V CMOS
3.3 V CMOS
3.3 V CMOS
Pin
Number
70
65
59
79
80
64
88
Interface
Analog
Analog
Analog
Analog
Analog
Analog
Both
87
89
73
74
48
Both
Analog
Analog
Analog
Analog
78
77
76
Both
Both
Both
Both
Both
Both
Both
AD9882A
Pin Type
Data Outputs
Data Clock Output
Digital Video Data
Inputs
Digital Video Clock
Inputs
Data Enable
Control Bits
RTERM
HDCP
Mnemonic
RED [7:0]
GREEN [7:0]
BLUE [7:0]
DATACK
RX0+
RX0–
RX1+
RX1–
RX2+
RX2–
RXC+
RXC–
DE
CTL [0:3]
RTERM
DDCSCL
DDCSDA
MCL
MDA
Function
Outputs of Converter Red, Bit 7 is the MSB
Outputs of Converter Green, Bit 7 is the MSB
Outputs of Converter Bue, Bit 7 is the MSB
Data Output Clock for the Analog and Digital
Interface
Digital Input Channel 0 True
Digital Input Channel 0 Complement
Digital Input Channel 1 True
Digital Input Channel 1 Complement
Digital Input Channel 2 True
Digital Input Channel 2 Complement
Digital Data Clock True
Digital Data Clock Complement
Data Enable
Decoded Control Bits
Sets Internal Termination Resistance
HDCP Slave Serial Port Data Clock
HDCP Slave Serial Port Data I/O
HDCP Master Serial Port Data Clock
HDCP Master Serial Port Data I/O
PIN DESCRIPTIONS OF SHARED PINS BETWEEN
ANALOG AND DIGITAL INTERFACES
3.3 V CMOS
3.3 V CMOS
3.3 V CMOS
3.3 V CMOS
3.3 V CMOS
3.3 V CMOS
Pin
Number
92–99
2–9
12–19
85
Interface
Both
Both
Both
Both
33
32
36
35
39
38
41
42
86
22–25
28
53
54
81
82
Digital
Digital
Digital
Digital
Digital
Digital
Digital
Digital
Digital
Digital
Digital
Digital
Digital
Digital
Digital
DATA OUTPUTS
RED—Data Output, Red Channel
HSOUT—Horizontal Sync Output
GREEN—Data Output, Green Channel
A reconstructed and phase-aligned version of the video Hsync.
The polarity of this output can be controlled via a serial bus bit.
In analog interface mode, the placement and duration are
variable. In digital interface mode, the placement and duration
are set by the graphics transmitter.
VSOUT—Vertical Sync Output
The separated Vsync from a composite signal or a direct passthrough of the Vsync input. The polarity of this output can be
controlled via a serial bus bit. The placement and duration in all
modes is set by the graphics transmitter.
SERIAL PORT (2-WIRE)
Value
3.3 V CMOS
3.3 V CMOS
3.3 V CMOS
3.3 V CMOS
BLUE—Data Output, Blue Channel
The main data outputs. Bit 7 is the MSB. These outputs are
shared between the two interfaces and behave in accordance
with the active interface. Refer to the Analog Interface and
Digital Interface sections.
DATACK—Data Output Clock
Just like the data outputs, the data clock output is shared
between the two interfaces. It behaves differently depending on
which interface is active. Refer to the DATACK—Data Output
Clock section to determine how this pin behaves. .
SDA—Serial Port Data I/O
SCL—Serial Port Data Clock
A0—Serial Port Address Input
For a full description of the 2-wire serial register, refer to the
2-Wire Serial Control Register Detail section.
Rev. 0 | Page 8 of 40
AD9882A
Table 5. Analog Interface Pin List
Pin Type
Analog Video Inputs
External Sync/Clock
Sync Outputs
Voltage Reference Clamp Voltages
PLL Filter
Power Supply
Mnemonic
RAIN
GAIN
BAIN
HSYNC
VSYNC
SOGIN
HSOUT
VSOUT
SOGOUT
REFBYPASS
MIDBYPASS
FILT
VD
PVD
VDD
GND
Function
Analog input for Converter R
Analog input for Converter G
Analog input for Converter B
Horizontal SYNC input
Vertical SYNC input
Sync-on-green input
Hsync output (phase-aligned with DATACK)
Vsync output
Composite SYNC
Internal reference bypass
Internal midscale voltage bypass
Connection for external filter components for
internal PLL
Main power supply
PLL power supply (nominally 3.3 V)
Output power supply
Ground
PIN FUNCTION DETAIL: ANALOG INTERFACE
Value
0.0 V to 1.0 V
0.0 V to 1.0 V
0.0 V to 1.0 V
3.3 V CMOS
3.3 V CMOS
0.0 V to 1.0 V
3.3 V CMOS
3.3 V CMOS
3.3 V CMOS
1.25 V
Pin
Number
70
65
59
79
80
64
88
87
89
73
74
48
3.15 V to 3.45 V
3.15 V to 3.45 V
2.2 V to 3.6 V
0V
The input includes a Schmitt trigger for noise immunity, with a
nominal input threshold of 1.5 V.
Inputs
RAIN—Analog Input for Red Channel
Electrostatic discharge (ESD) protection diodes conduct heavily
if this pin is driven more than 0.5 V above the maximum
tolerance voltage (3.3 V) or more than 0.5 V below ground.
GAIN—Analog Input for Green Channel
BAIN—Analog Input for Blue Channel
VSYNC—Vertical Sync Input
High impedance inputs that accept the red, green, and blue
channel graphics signals, respectively. For RGB, the three
channels are identical and can be used for any colors, but colors
are assigned for convenient reference.
For proper 4:2:2 formatting in a YPbPr application, the Y must
be connected to the GAIN input, the Pb must be connected to the
BAIN input, and the Pr must be connected to the RAIN input.
They accommodate input signals ranging from 0.5 V to 1.0 V
full scale. Signals should be ac-coupled to these pins to support
clamp operation.
Hsync—Horizontal Sync Input
This input receives a logic signal that establishes the horizontal
timing reference and provides the frequency reference for pixel
clock generation. The logic sense of this pin is controlled by
Serial Register Bit 0x10, Bit 6 (Hsync polarity). Only the leading
edge of Hsync is used by the PLL; the trailing edge is used for
clamp timing. When Hsync polarity = 0, the falling edge of
Hsync is used. When Hsync polarity = 1, the rising edge is
active.
This is the input for vertical sync.
SOGIN—Sync-on-Green Input
This input is provided to assist with processing signals with
embedded sync, typically on the green channel. The pin is
connected to a high speed comparator with an internally
generated threshold, which is set by the value of Register 0x0F,
Bits 7 to 3.
When connected to an ac-coupled graphics signal with
embedded sync, it produces a noninverting digital output
on SOGOUT.
When not used, this input should be left unconnected. For
more details on this function and how it should be configured,
refer to the Sync-on-Green (SOG) section.
SOGOUT—Sync-on-Green Slicer Output
This pin can be programmed to produce either the output from
the sync-on-green slicer comparator or an unprocessed but
delayed version of the Hsync input. See Figure 20, the sync
processing block diagram, to view how this pin is connected.
Note that the output from this pin is the composite sync
without additional processing from the AD9882A.
Rev. 0 | Page 9 of 40
AD9882A
FILT—External Filter Connection
RED—Data Output, Red Channel
For proper operation, the pixel clock generator PLL requires an
external filter. Connect the filter as shown in Figure 8 to this
pin. For optimal performance, minimize noise and parasitics on
this node.
GREEN—Data Output, Green Channel
REFBYPASS—Internal Reference Bypass
The delay from pixel sampling time to output is fixed. When the
sampling time is changed by adjusting the phase register, the
output timing is shifted as well. The DATACK and HSOUT
outputs are also moved, so the timing relationship among the
signals is maintained. See the Timing Diagrams section for
more information.
Bypass for the internal 1.25 V band gap reference. It should be
connected to ground through a 0.1 µF capacitor.
The absolute accuracy of this reference is ±4%, and the temperature coefficient is ±50 ppm, which is adequate for most
AD9882A applications. If higher accuracy is required, an
external reference can be employed instead.
BLUE—Data Output, Blue Channel
These are the main data outputs. Bit 7 is the MSB.
POWER SUPPLY
VD—Main Power Supply
MIDBYPASS—Midscale Voltage Reference Bypass
Bypass for the internal midscale voltage reference. It should be
connected to ground through a 0.1 µF capacitor. The exact
voltage varies with the gain setting of the red channel.
HSOUT—Horizontal Sync Output
A reconstructed and phase-aligned version of the Hsync input.
The duration of Hsync can be programmed only on the analog
interface, not the digital.
DATACK—Data Output Clock
The data clock output signal is used to clock the output data
and HSOUT into external logic. It is produced by the internal
clock generator and is synchronous with the internal pixel
sampling clock.
These pins supply power to the main elements of the circuit.
They should be as quiet as possible.
VDD—Digital Output Power Supply
A large number of output pins (up to 25) switching at high
speed (up to 140 MHz) generates a lot of power supply transients. These supply pins are identified separately from the VD
pins, so special care must be taken to minimize output noise
transferred into the sensitive analog circuitry.
If the AD9882A is interfacing with lower voltage logic, VDD can
be connected to a lower supply voltage (as low as 2.2 V) for
compatibility.
PVD—Clock Generator Power Supply
The most sensitive portion of the AD9882A is the clock generation circuitry. These pins provide power to the clock PLL and
help the user design for optimal performance. The designer
should provide noise-free power to these pins.
When the sampling time is changed by adjusting the phase
register, the output timing is shifted as well. The data bits,
DATACK, and HSOUT outputs are all moved, so the timing
relationship among the signals is maintained.
GND—Ground
VSOUT—Vertical Sync Output
The separated Vsync from a composite signal or a direct passthrough of the Vsync input. The polarity of this output can be
controlled via Register 0x10, Bit 2. The placement and duration
in all modes is set by the graphics transmitter.
The ground return for all circuitry on-chip. It is recommended
that the AD9882A be assembled on a single solid ground plane,
with careful attention to ground current paths.
Rev. 0 | Page 10 of 40
AD9882A
Table 6. Interface Selection Controls
AIO
(0xF Bit 2)
1
Analog Interface
Detect
X
Digital Interface
Detect
X
0
0
X
AIS
(0x0F, Bit 1)
0
1
None
0
1
X
Active
Interface
Analog
Digital
Neither interface
was detected.
Digital
1
0
X
Analog
1
1
0
Analog
1
Digital
Description
Force the analog interface active.
Force the digital interface active.
Both interfaces are powered down.
The digital interface was detected. Power
down the analog interface.
The analog interface was detected. Power
down the digital interface.
Both interfaces were detected. The
analog interface gets priority.
Both interfaces were detected. The digital
interface gets priority.
Table 7. Power-Down Modes, 4:2:2 and 4:4:4 Format Descriptions
PowerDown1
1
Analog
Interface
Detect2
0
Digital
Interface
Detect3
0
Active
Interface
Override
0
Active
Interface
Select
X
4:2:2
Formatting
X
Digital Interface On
1
0
1
0
X
X
Analog Interface On
4:4:4 Format
1
1
0
0
X
0
Analog Interface On
4:2:2 Format
1
1
0
0
X
1
Serial Bus
Arbitrated Interface
Serial Bus
Arbitrated Interface
Serial Bus
Arbitrated Interface
Override to Analog
Interface
Override to Analog
Interface
Override to Digital
Interface
Absolute PowerDown
1
1
1
1
0
0
1
1
1
1
0
1
1
1
1
1
1
X
1
1
X
1
0
0
1
1
X
1
0
1
1
X
1
1
1
X
Same as the analog interface
4:4:4 mode
Same as the analog interface
4:2:2 mode
Same as digital interface mode
0
X
X
X
X
X
Serial bus
Mode
Soft Power-Down
(Seek Mode)
1
Power-down is controlled via Bit 1 in Serial Bus Register 0x14.
Analog interface detect is determined by OR’ing Bits 7, 6, and 5 in Serial Bus Register 0x15.
3
Digital interface detect is determined by Bit 4 in Serial Bus Register 0x15.
2
Rev. 0 | Page 11 of 40
Data Sheet Signals Powered
On
Serial bus, digital interface clock
detect, analog interface clock
detect, SOG
Serial bus; digital interface and
analog interface activity detect;
SOG, band gap reference; red,
green, and blue outputs
Serial bus; analog interface and
digital interface clock detect;
SOG, band gap reference; red,
green, and blue outputs
Serial bus; analog interface and
digital interface clock detect;
SOG, band gap reference; red
and green outputs only
Same as the analog interface in
4:4:4 mode
Same as the analog interface in
4:2:2 mode
Same as digital interface mode
AD9882A
THEORY OF OPERATION: INTERFACE DETECTION
ACTIVE INTERFACE DETECTION AND SELECTION
POWER MANAGEMENT
The AD9882A includes circuitry to detect whether an interface
is active or not (see Table 6).
The AD9882A is a dual interface device with shared outputs.
Only one interface can be used at a time. For this reason, the
chip automatically powers down the unused interface. When
the analog interface is being used, most of the digital interface
circuitry is powered down, and vice versa. This helps to minimize the AD9882A total power dissipation. In addition, if
neither interface has activity on it, the chip powers down both
interfaces. The AD9882A uses the activity detect circuits, the
active interface bits in Serial Register 0x15, the active interface
override bits in Register 0x0F, Bits 2 and 1, and the power-down
bit in Register 0x14, Bit 1, to determine the correct power state.
In a given power mode, not all circuitry in the inactive interface
is powered down completely.
For detecting the analog interface, the circuitry monitors the
presence of Hsync, Vsync, and sync-on-green. The result of the
detection circuitry can be read from the 2-wire serial interface
bus at Address 0x15, Bits 7, 5, and 6, respectively. If one of these
sync signals disappears, the maximum time it takes for the
circuitry to detect it is 100 ms.
For detecting the digital interface, there are two stages of
detection. The first stage searches for the presence of the digital
interface clock. The circuitry for detecting the digital interface
clock is active even when the digital interface is powered down.
The result of this detection stage can be read from the 2-wire
serial interface bus at Address 0x15, Bit 4. If the clock disappears, the maximum time it takes for the circuitry to detect it is
100 ms. Once a digital interface clock is detected, the digital
interface is powered up and the second stage of detection
begins. During the second stage, the circuitry searches for
32 consecutive DEs. Once 32 DEs are found, the detection
process is complete.
When the digital interface is active, the band gap reference
Hsync, Vsync, and SOG detect circuitry remain powered-up.
When the analog interface is active, the digital interface clock
detect circuit is not powered-down. Table 7 summarizes how
the AD9882A determines which power mode to be in and
which circuitry is powered on/off in each of these modes. The
power-down command has priority, then the active interface
override, and then the automatic circuitry.
There is an override for the automatic interface selection. It is
the AIO (Active Interface Override) bit, Register 0x0F, Bit 2.
When the AIO bit is set to Logic 0, the automatic circuitry is
used. When the AIO bit is set to Logic 1, the AIS (Active
Interface Select) bit (Register 0x0F, Bit 1) is used to determine
the active interface rather than the automatic circuitry.
Rev. 0 | Page 12 of 40
AD9882A
THEORY OF OPERATION AND DESIGN GUIDE: ANALOG INTERFACE
GENERAL DESCRIPTION
47nF
RGB
INPUT
The AD9882A is a fully integrated solution for capturing analog
RGB signals and digitizing them for display on flat panel monitors or projectors. The device is ideal for implementing a computer interface for HDTV monitors or as the front end to high
performance video scan converters.
Implemented in a high performance CMOS process, the interface can capture signals with pixel rates of up to 140 MHz.
The AD9882A includes all necessary input buffering, signal dc
restoration (clamping), offset and gain (brightness and contrast)
adjustment, pixel clock generation, sampling phase control, and
output data formatting. All controls are programmable via a
2-wire serial interface. Full integration of these sensitive analog
functions makes the system design straightforward and less
sensitive to the physical and electrical environment.
With a typical power dissipation of only 875 mW and an operating temperature range of 0°C to 70°C, the device requires no
special environmental considerations.
INPUT SIGNAL HANDLING
The AD9882A has three high impedance analog input pins for
the red, green, and blue channels. They will accommodate
signals ranging from 0.5 V to 1.0 V p-p.
RAIN
GAIN
BAIN
05123-003
75Ω
Figure 3. Analog Input Interface Circuit
HSYNC AND VSYNC INPUTS
The AD9882A receives a horizontal sync signal and uses it to
generate the pixel clock and clamp timing. This can be either a
sync signal directly from the graphics source or a preprocessed
TTL or CMOS level signal.
The Hsync input includes a Schmitt trigger buffer and is
capable of handling signals with long rise times, with superior
noise immunity. In typical PC-based graphic systems, the sync
signals are simply TTL level drivers, feeding unshielded wires in
the monitor cable. As such, no termination is required.
SERIAL CONTROL PORT
The serial control port is designed for 3.3 V logic. If there are
5 V drivers on the bus, these pins should be protected with
150 Ω series resistors placed between the pull-up resistors and
the input pins.
OUTPUT SIGNAL HANDLING
Signals are typically brought onto the interface board via a
DVI-I connector, a 15-pin D connector, or BNC connectors.
The AD9882A should be located as close as practical to the
input connector. Signals should be routed via matchedimpedance traces (normally 75 Ω) to the IC input pins.
The digital outputs are designed and specified to operate from a
3.3 V power supply (VDD). They can also work with a VDD as low
as 2.5 V for compatibility with other 2.5 V logic.
CLAMPING
At that point, the signal should be resistively terminated (75 Ω
to the signal ground return) and capacitively coupled to the
AD9882A inputs through 47 nF capacitors. These capacitors
form part of the dc restoration circuit (see Figure 9).
In an ideal world of perfectly matched impedances, the best
performance can be obtained with the widest possible signal
bandwidth. The wide bandwidth inputs of the AD9882A
(300 MHz) can track the input signal continuously as it moves
from one pixel level to the next and digitize the pixel during a
long, flat pixel time. In many systems, however, there are
mismatches, reflections, and noise, which can result in excessive
ringing and distortion of the input waveform. This makes it
more difficult to establish a sampling phase that provides good
image quality. It has been shown that a small inductor in series
with the input is effective in rolling off the input bandwidth
slightly and providing a high quality signal over a wider range
of conditions. Using a Fair-Rite #2508051217Z0 high speed
signal chip bead inductor in the circuit of Figure 9 gives good
results in most applications.
RGB Clamping
To properly digitize the incoming signal, the dc offset of the
input must be adjusted to fit the range of the on-board ADCs.
Most graphics systems produce RGB signals with black at
ground and white at approximately 0.75 V. However, if sync
signals are embedded in the graphics, the sync tip is often at
ground, and black is at 300 mV; white will be approximately
1.0 V. Some common RGB line amplifier boxes use emitterfollower buffers to split signals and increase drive capability.
This introduces a 700 mV dc offset to the signal, which is
removed by clamping for proper capture by the AD9882A.
The key to clamping is to identify a portion (time) of the signal
when the graphics system is known to be producing black.
Originating from CRT displays, the electron beam is blanked by
sending a black level during horizontal retrace to prevent
disturbing the image. Most graphics systems maintain this
format of sending a black level between active video lines.
Rev. 0 | Page 13 of 40
AD9882A
The offset control shifts the entire input range, resulting in a
change in image brightness. Three 7-bit registers (red offset,
green offset, and blue offset) provide independent settings for
each channel.
The offset controls provide a ±63 LSB adjustment range. This
range is connected with the full-scale range, so if the input
range is doubled (from 0.5 V to 1.0 V), the offset step size is also
doubled (from 2 mV per step to 4 mV per step).
Figure 4 illustrates the interaction of gain and offset controls.
The magnitude of an LSB in offset adjustment is proportional to
the full-scale range, so changing the full-scale range also
changes the offset. The change is minimal if the offset setting is
near midscale. When changing the offset, the full-scale range is
not affected, but the full-scale level is shifted by the same
amount as the zero-scale level.
The value of the external input coupling capacitor affects the
performance of the clamp. If the value is too small, there can be
an amplitude change during a horizontal line time (between
clamping intervals). If the capacitor is too large, then it takes
excessively long for the clamp to recover from a large change in
incoming signal offset. The recommended value (47 nF) results
in recovery from a step error of 100 mV to within one-half LSB
in 30 lines, using a clamp duration of 20 pixel periods on a
75 Hz SXGA signal.
0x
7F
These are both 8-bit values, providing considerable flexibility in
clamp generation. The clamp timing is referenced to the trailing
edge of Hsync, because the back porch (black reference) always
follows Hsync. A good starting point for establishing clamping
is to set the clamp placement to 0x08 (providing eight pixel
periods for the graphics signal to stabilize after sync) and set the
clamp duration to 0x14 (giving the clamp 20 pixel periods to
reestablish the black reference).
A code of 0 establishes a minimum input range of 0.5 V; a code
of 255 corresponds with the maximum range of 1.0 V. Note that
increasing the gain setting results in an image with less contrast.
=
The clamp timing is established by the AD9882A internal clamp
timing generator. The clamp placement register (0x05) is
programmed with the number of pixel times that should pass
after the trailing edge of Hsync before clamping starts. A second
register (clamp duration, 0x06) sets the duration of the clamp.
The AD9882A can accommodate input signals with inputs
ranging from 0.5 V to 1.0 V full scale. The full-scale range is set
in three 8-bit registers (red gain, green gain, and blue gain).
1.0 V
O
FF
SE
T
In systems with embedded sync, a blacker-than-black signal
(Hsync) is produced briefly to signal the CRT that it is time to
begin a retrace. For obvious reasons, it is important to avoid
clamping on the tip of Hsync. Fortunately, there is virtually
always a period following Hsync called the back porch, in which
a good black reference is provided. This is the time when
clamping should be done.
GAIN AND OFFSET CONTROL
INPUT RANGE
An offset is then introduced, which results in the ADC
producing a black output (Code 0x00) when the known black
input is present. The offset then remains in place when other
signal levels are processed, and the entire signal is shifted to
eliminate offset errors.
FF
O
0.5 V
OF
T
SE
=
3F
0x
=
ET
FS
00
0x
YUV Clamping
Clamping to midscale rather than ground can be accomplished
by setting the clamp select bits in the serial bus register. Each of
the three converters has its own selection bit, so that they can be
clamped to either midscale or ground independently. These bits
are located in Register 0x11 and are Bits 4 to 6. The midscale
reference voltage that each ADC clamps to is provided on the
MIDBYPASS pin (Pin 74). This pin should be bypassed to
ground with a 0.1 µF capacitor (even if midscale clamping is not
required).
Rev. 0 | Page 14 of 40
T=
OFFSE
0.0 V
0x00
0x7F
OFFSET = 0x3F
0xFF
OF F S
ET =
0x00
GAIN
Figure 4. Gain and Offset Control
05123-004
YUV signals are slightly different from RGB signals in that the
dc reference level (black level in RGB signals) is at the midpoint
of the U and V video. For these signals, it might be necessary to
clamp to the midscale range of the ADC range (0x80) rather
than the bottom of the ADC range (0x00).
AD9882A
PIXEL CLOCK
SYNC-ON-GREEN (SOG)
INVALID SAMPLE TIMES
05123-006
The sync-on-green input operates in two steps. First, it sets a
baseline clamp level off of the incoming video signal with a
negative peak detector. Second, it sets the sync trigger level
(nominally 150 mV above the negative peak). The exact trigger
level is variable and can be programmed via Register 0x0F,
Bits 7 to 3. The sync-on-green input must be ac-coupled to the
green analog input through its own capacitor as shown in
Figure 5. The value of the capacitor must be 1 nF ±20%. If syncon-green is not used, this connection is not required and
SOGIN should be left unconnected. Note that the sync-ongreen signal is always negative polarity. See the Sync Processing
Engine section for further information.
Figure 6. Pixel Sampling Times
Any jitter in the clock reduces the precision with which the
sampling time can be determined and must also be subtracted
from the stable pixel time.
47nF
RAIN
47nF
BAIN
47nF
Considerable care has been taken in the design of the
AD9882A’s clock generation circuit to minimize jitter. As
indicated in Figure 7, the clock jitter of the AD9882A is less
than 6% of the total pixel time in all operating modes, making
negligible the reduction in the valid sampling time due to jitter.
Figure 5. Typical Clamp Configuration
CLOCK GENERATION
10
8
6
4
2
05123-007
The stability of this clock is a very important element in providing the clearest and most stable image. During each pixel time,
there is a period during which the signal is slewing from the old
pixel amplitude and settling at its new value. Then there is a
time when the input voltage is stable, before the signal must
slew to a new value (Figure 6). The ratio of the slewing time to
the stable time is a function of the bandwidth of the graphics
DAC and the bandwidth of the transmission system (cable and
termination). It is also a function of the overall pixel rate.
Clearly, if the dynamic characteristics of the system remain
fixed, then the slewing and settling time is likewise fixed. This
time must be subtracted from the total pixel period, leaving the
stable period. At higher pixel frequencies, the total cycle time is
shorter, and the stable pixel time becomes shorter as well.
PIXEL CLOCK JITTER (p-p) (%)
A phase-locked loop (PLL) is employed to generate the pixel
clock. The Hsync input provides a reference frequency for the
PLL. A voltage controlled oscillator (VCO) generates a much
higher pixel clock frequency. This pixel clock is divided by the
PLL divide value (Registers 0x01 and 0x02) and phase compared with the Hsync input. Any error is used to shift the VCO
frequency and maintain lock between the two signals.
0
25.1
31.5
36.0
40.0
50.0
56.2
65.0
75.0
78.7
85.5
94.5 108.0 135.0
PIXEL CLOCK FREQUENCY (MHz)
Figure 7. Pixel Clock Jitter vs. Frequency
The PLL characteristics are determined by the loop filter design,
the PLL charge pump current, and the VCO range setting. The
loop filter design is illustrated in Figure 8. Recommended
settings of VCO range and charge pump current for VESA
standard display modes are listed in Table 10.
CZ
0.082µF
RZ
2.74kΩ
CP
0.0082µF
FILT
PVD
05123-008
SOGIN
05123-005
GAIN
1nF
Figure 8. PLL Loop Filter Detail
Rev. 0 | Page 15 of 40
AD9882A
Four programmable registers are provided to optimize the
performance of the PLL. These registers are
1.
Table 8. VCO Frequency Ranges
The 12-bit divisor register (Registers 0x01 and 0x02). The
input Hsync frequencies range from 15 kHz to 110 kHz.
The PLL multiplies the frequency of the Hsync signal,
producing pixel clock frequencies in the range of 12 MHz
to 140 MHz. The divisor register controls the exact
multiplication factor. This register can be set to any value
between 221 and 4095. The divide ratio that is actually
used is the programmed divide ratio plus one.
2.
The 2-bit VCO range register (Register 0x03, Bits 6 and 7).
To improve the noise performance of the AD9882A, the
VCO operating frequency range is divided into three
overlapping regions. The VCO range register sets this
operating range. The frequency ranges for the lowest and
highest regions are shown in Table 8.
3.
The 3-bit charge pump current register (Register 0x03,
Bits 3 to 5). This register allows the current that drives the
low-pass loop filter to be varied. The possible current
values are listed in Table 9.
4.
The 5-bit Phase Adjust Register (Register 0x04, Bits 3 to 7).
The phase of the generated sampling clock can be shifted
to locate an optimum sampling point within a clock cycle.
The phase adjust register provides 32 phase-shift steps of
11.25° each. The Hsync signal with an identical phase shift
is available through the HSOUT pin.
PV1
0
0
1
PV0
0
1
0
Pixel Clock Range (MHz)
12–41
41–82
82–140
Table 9. Charge Pump Current/Control Bits
Ip2
0
0
0
0
1
1
1
1
Ip1
0
0
1
1
0
0
1
1
Ip0
0
1
0
1
0
1
0
1
Current (µA)
50
100
150
250
350
500
750
1500
The coast function allows the PLL to continue to run at the
same frequency, in the absence of the incoming Hsync signal or
during disturbances in Hsync (such as equalization pulses).
This can be used during the vertical sync period, or any other
time that the Hsync signal is unavailable. Also, the polarity of
the Hsync signal can be set through the Hsync polarity bit
(Register 0x10, Bit 6). If not using automatic polarity detection,
the Hsync polarity bit should be set to match the polarity of the
Hsync input signal.
Table 10. Recommended VCO Range and Charge Pump Current Settings for Standard Display Formats
Standard
VGA
Refresh Resolution
640 × 480
SVGA
800 × 600
XGA
1024 × 768
SXGA
1280 × 1024
TV Modes
480i
480p
720p
1080i
Horizontal Rate (Hz)
60
72
75
85
56
60
72
75
85
60
70
75
80
85
60
75
60
60
60
60
Frequency (kHz)
31.500
37.700
37.500
43.300
35.100
37.900
48.100
46.900
53.700
48.400
56.500
60.000
64.000
68.300
64.000
80.000
15.750
31.470
45.000
33.750
Rev. 0 | Page 16 of 40
Pixel Rate (MHz)
25.175
31.500
31.500
36.000
36.000
40.000
50.000
49.500
56.250
65.000
75.000
78.750
85.500
94.500
108.000
135.000
13.500
27.000
74.500
74.500
VCORNGE
00
00
00
00
00
00
01
01
01
01
01
01
10
10
10
10
00
00
01
01
CURRENT
101
101
101
110
101
110
101
101
101
101
110
110
101
101
101
110
001
100
101
101
AD9882A
TIMING: ANALOG INTERFACE
The following timing diagrams show the operation of the
AD9882A. The output data clock signal is created so that its
rising edge always occurs between data transitions and can be
used to latch the output data externally.
tPER
tDCYCLE
DATACK
tSKEW
05123-009
tSKEW
DATA
HSOUT
Figure 9. Output Timing
Hsync Timing
Horizontal sync (Hsync) is processed in the AD9882A to
eliminate ambiguity in the timing of the leading edge with
respect to the phase-delayed pixel clock and data. The Hsync
input is used as a reference to generate the pixel sampling clock.
The sampling phase can be adjusted, with respect to Hsync,
through a full 360° in 32 steps via the phase adjust register
(Register 0x04) to optimize the pixel sampling time. Display
systems use Hsync to align memory and display write cycles, so
it is important to have a stable timing relationship between
Hsync output (HSOUT) and data clock (DATACK).
Coast Timing
In most computer systems, the Hsync signal is provided
continuously on a dedicated wire. In these systems, the
coast function is unnecessary and should be disabled using
Register 0x11, Bits 1 to 3.
In some systems, however, Hsync is disturbed during the vertical sync period (Vsync). In other cases, Hsync pulses disappear.
In other systems, such as those that employ composite sync
(Csync) signals or embedded sync-on-green (SOG), Hsync
includes equalization pulses or other distortions during Vsync.
To avoid upsetting the clock generator during Vsync, it is
important to ignore these distortions. If the pixel clock PLL sees
extraneous pulses, it attempts to lock to this new frequency and
has changed frequency by the end of the Vsync period. It then
takes a few lines of correct Hsync timing to recover at the
beginning of a new frame, resulting in a tearing of the image at
the top of the display.
The coast function is provided to eliminate this problem. It is an
internally generated signal, created by the sync processing
engine that disables the PLL input and allows the clock to freerun at its then-current frequency. The PLL can free-run for
several lines without significant frequency drift.
Three things happen to horizontal sync in the AD9882A. First,
the polarity of Hsync input is determined and therefore has a
known output polarity. The known output polarity can be
programmed either active high or active low (Register 0x10,
Bit 5). Second, HSOUT is aligned with DATACK and data
outputs. Third, the duration of HSOUT (in pixel clocks) is set
via Register 0x07. HSOUT is the sync signal that should be used
to drive the rest of the display system.
Rev. 0 | Page 17 of 40
AD9882A
TIMING DIAGRAMS
RGBIN
P0
P1
P2
P3
P4
P5
P6
P7
HSYNC
PXCK
HS
5-PIPE DELAY
ADCCK
DATACK
D1
D2
HSOUT
D3
D4
D5
D6
D7
05123-010
D0
DATAOUT
VARIABLE DURATION
Figure 10. 4:4:4 Mode (for RGB and YPbPr)
RGBIN
P0
P1
P2
P3
P4
P5
P6
P7
HSYNC
PXCK
HS
5-PIPE DELAY
ADCCK
GOUTA
Y0
Y1
Y2
Y3
Y4
Y5
Y6
Y7
ROUTA
Pb0
Pr0
Pb2
Pr2
Pb4
Pr4
Pb6
Pr6
HSOUT
VARIABLE DURATION
Figure 11. 4:4:2 Mode (for YPbPr Only)
Rev. 0 | Page 18 of 40
05123-011
DATACK
AD9882A
THEORY OF OPERATION: DIGITAL INTERFACE
Table 11. Digital Interface Pin List
Pin Type
Digital Video Data
Inputs
Digital Video Clock
Inputs
Termination Control
Outputs
HDCP
Power Supply
Mnemonic
RX0+
RX0–
RX1+
RX1–
RX2+
RX2–
RXC+
RXC–
RTERM
DE
HSOUT
VSOUT
CTL0, CTL1, CTL2, CTL3
DDCSCL
DDCSDA
MCL
MDA
VD
PVD
VDD
GND
Function
Digital input Channel 0 true
Digital input Channel 0 complement
Digital input Channel 1 true
Digital input Channel 1 complement
Digital input Channel 2 true
Digital input Channel 2 Complement
Digital data clock true
Digital data clock complement
Control pin for setting the internal termination
resistance
Data enable
Hsync output
Vsync output
Decoded control bit outputs
HDCP slave serial port data clock
HDCP slave serial port data I/O
HDCP master serial port data clock
HDCP master serial port data I/O
Main power supply
PLL power Supply
Output power supply
Ground supply
Value
3.3 V CMOS
3.3 V CMOS
3.3 V CMOS
3.3 V CMOS
3.3 V CMOS
3.3 V CMOS
3.3 V CMOS
3.3 V CMOS
3.15 V to 3.45 V
3.15 V to 3.45 V
2.2 V to 3.6 V
0V
Pin
Number
33
32
36
35
39
38
41
42
28
86
88
87
22–25
53
54
81
82
DIGITAL INTERFACE PIN DESCRIPTIONS
Digital Data Inputs
Termination Control
RX0+ Positive Differential Input Data (Channel 0)
RTERM—Internal Termination Set Pin
RX0– Negative Differential Input Data (Channel 0)
This pin is used to set the termination resistance for all of the
digital interface high speed inputs. To set, place a resistor of
value equal to 10× the desired input termination resistance
between this pin (Pin 28) and ground supply. Typically, the
value of this resistor should be 500 Ω.
RX1+ Positive Differential Input Data (Channel 1)
RX1– Negative Differential Input Data (Channel 1)
RX2+ Positive Differential Input Data (Channel 2)
Outputs
RX2– Negative Differential Input Data (Channel 2)
DE—Data Enable Output
These six pins receive three pairs of differential, low voltage
swing input pixel data from a DVI transmitter.
This pin outputs the state of data enable (DE). The AD9882A
decodes DE from the incoming stream of data. The DE signal is
high during active video and is low while there is no active
video.
Digital Clock Inputs
RXC+ Positive Differential Input Clock
DDCSCL—HDCP Slave Serial Port Data Clock
RXC– Negative Differential Input Clock
These two pins receive the differential, low voltage swing input
pixel clock from a DVI transmitter.
Used for communicating with the HDCP-enabled DVI
transmitter.
DDCSDA—HDCP Slave Serial Port I/O
For use in communicating with the HDCP-enabled DVI
transmitter.
Rev. 0 | Page 19 of 40
AD9882A
Connects to the EEPROM for reading the encrypted HDCP
keys.
The AD9882A receives these characters and uses them to set
the video frame boundaries and the phase recovery loop for
each channel. There are four special characters that can be
received. They are used to identify the top, bottom, left side, and
right side of each video frame. The data receiver can
differentiate these special characters from active data because
the special characters have a different number of transitions per
data frame.
CTL—Digital Control Outputs
CHANNEL RESYNCHRONIZATION
These pins output the control signals for the red and green
channels. CTL0 and CTL1 correspond to the red channel’s
input, while CTL2 and CTL3 correspond to the green channel’s
input.
The purpose of the channel resynchronization block is to
resynchronize the three data channels to a single internal data
clock. Coming into this block, all three data channels can be on
different phases of the 3× oversampling PLL clock (0°, 120°, and
240°). This block can resynchronize the channels from a worstcase skew of one full input period (8.93 ns at 112 MHz).
MCL—HDCP Master Serial Port Data Clock
Connects to the EEPROM for reading the encrypted HDCP
keys.
MDA—HDCP Master Serial Port Data I/O
Power Supply
VD—Main Power Supply
DATA DECODER
It should be as quiet as possible.
It should be as quiet as possible.
The data decoder receives frames of data and sync signals from
the data capture block (in 10-bit parallel words) and decodes
them into groups of eight RGB bits, two control bits, and a data
enable bit (DE).
VDD—Outputs Power Supply
HDCP
The power for the data and clock outputs. It can run at 3.3 V
or 2.5 V.
The AD9882A contains all the circuitry necessary for
decryption of a high bandwidth digital content protection
encoded DVI video stream. A typical HDCP implementation
is shown in Figure 12. Several features of the AD9882A make
this possible and add functionality to ease the implementation
of HDCP.
PVD—PLL Power Supply
GND—Ground
The ground return for all circuitry on the device. It is recommended that the application circuit board have a single, solid
ground plane.
CAPTURING THE ENCODED DATA
The first step in recovering the encoded data is to capture the
raw data. To accomplish this, the AD9882A employs a high
speed phase-locked loop (PLL) to generate clocks capable of
over sampling the data at the correct frequency. The data
capture circuitry continuously monitors the incoming data
during horizontal and vertical blanking times (when DE is low)
and selects the best sampling phase for each data channel
independently. The phase information is stored and used until
the next blanking period (one video line).
DATA FRAMES
The digital interface data is captured in groups of 10 bits each,
which are called data frames. During the active data period,
each frame is made up of the nine encoded video data bits and
one dc-balancing bit. The data capture block receives this data
serially but outputs each frame in parallel 10-bit words.
SPECIAL CHARACTERS
During periods of horizontal or vertical blanking time (when
DE is low), the digital transmitter transmits special characters.
The basic components of HDCP are included in the AD9882A.
A slave serial bus connects to the DDC clock and DDC data
pins on the DVI connector to allow the HDCP-enabled
DVI transmitter to coordinate the HDCP algorithm with
the AD9882A. A second serial port (MDA/MCL) allows the
AD9882A to read the HDCP keys and key selection vector
(KSV) stored in an external serial EEPROM. When
transmitting encrypted video, the DVI transmitter enables
HDCP through the DDC port. The AD9882A then decodes the
DVI stream using information provided by the transmitter,
HDCP keys, and KSV.
The AD9882A allows the MDA and MCL pins to be threestated using the MDA/MCL three-state bit (Register 0x1B, Bit
7) in the configuration registers. The three-state feature allows
the EEPROM to be programmed in-circuit. The MDA/MCL
port must be three-stated before attempting to program the
EEPROM using an external master. The keys will be stored in
an I2C® compatible 3.3 V serial EEPROM of at least 512 bytes in
size. The EEPROM should have a device address of 0xA0.
Proprietary software licensed from Analog Devices encrypts the
keys and creates properly formatted EEPROM images for use in
a production environment. Encrypting the keys helps maintain
Rev. 0 | Page 20 of 40
AD9882A
ADI provides a royalty-free license for the proprietary software
needed by customers to encrypt the keys between the AD9882A
and the EEPROM only after customers provide evidence of a
completed HDCP adopter’s license agreement and sign ADI’s
software license agreement. The adopter’s license agreement is
maintained by Digital Content Protection, LLC, and can be
downloaded from www.digital-cp.com. To obtain ADI’s
software license agreement, contact the Display Electronics
Product Line directly by sending an email to
[email protected]
3.3V
DVI
CONNECTOR
3.3V
5kΩ PULL-UP
RESISTORS
5kΩ PULL-UP
RESISTORS
DDC CLOCK
DDC SCL MCL
AD9882A
DDC DATA
D
DDC SDA MDA
S
3.3V
150Ω SERIES
RESISTOR
10kΩ
PULL-UP RESISTOR
DVI-VCC
Rev. 0 | Page 21 of 40
Figure 12. HDCP Implementation Using the AD9882A
SCL
EEPROM
SDA
05123-012
the confidentiality of the HDCP keys as required by the
HDCP v. 1.0 specification. The AD9882A includes hardware
for decrypting the keys in the external EEPROM.
AD9882A
GENERAL TIMING DIAGRAMS: DIGITAL INTERFACE
Rx0
Rx0
VDIFF = 0V
VDIFF = 0V
Rx1
tCCS
VDIFF = 0V
05123-013
tCCS
Rx2
VDIFF = 0V
05123-015
Rx1
Rx2
Figure 13. Digital Output Rise and Fall Times
Figure 15. Channel-to-Channel Skew Timing
TCIP, RCIP
TCIL, RCIL
05123-014
TCIH, RCIH
Figure 14. Clock Cycle High/Low Times
TIMING MODE DIAGRAMS: DIGITAL INTERFACE
INTERNAL
ODCLK
TST
DATACK
FIRST PIXEL
SECOND PIXEL
THIRD PIXEL
FOURTH PIXEL
05123-016
DATAOUT
FOURTH PIXEL
05123-017
DE
Figure 16. DVI CLK Invert = 1 (Register 14, Bit 4)
INTERNAL
ODCLK
TST
DATACK
DE
DATAOUT
FIRST PIXEL
SECOND PIXEL
THIRD PIXEL
Figure 17. DVI CLK Invert = 0 (Register 14, Bit 4)
Rev. 0 | Page 22 of 40
AD9882A
2-WIRE SERIAL REGISTER MAP
The AD9882A is initialized and controlled by a set of registers that determines the operating modes. An external controller is employed
to write and read the control registers through the 2-wire serial interface port.
Table 12. Control Register Map
Hexadecimal
Address
0x00
0x01
Read and
Write or
Read Only
RO
R/W
Bit
7–0
7–0
0x02
R/W
0x03
R/W
0x04
Default
Value
0110 1001
Register Name
Chip Revisions
PLL Div MSB
7–4
1101 ****
PLL Div LSB
R/W
7–6
5–3
7–3
01** ****
**00 1***
1000 0***
VCO Range
Charge Pump
Phase Adjust
0x05
R/W
7–0
0000 1000
Clamp Placement
0x06
R/W
7–0
0001 0100
Clamp Duration
0x07
R/W
7–0
0010 0000
0x08
R/W
7–0
1000 0000
Hsync Output
Pulse Width
Red Gain
0x09
R/W
7–0
1000 0000
Green Gain
0x0A
R/W
7–0
1000 0000
Blue Gain
0x0B
R/W
7–1
1000 000*
Red Offset
0x0C
R/W
7–1
1000 000*
Green Offset
0x0D
R/W
7–1
1000 000*
Blue Offset
0x0E
R/W
7–0
0010 0000
Sync Separator
Threshold
0x0F
R/W
7–3
0111 1***
2
**** *0**
1
**** **0*
Sync-on-Green
Threshold
Active Interface
Override
Active Interface
Select
0x10
R/W
7
0*** ****
6
*1** ****
5
**0* ****
Hsync Polarity
Override
Input Hsync
Polarity
Output Hsync
Polarity
Function
An 8-bit register that represents the silicon level.
This register is for Bits [11:4] of the PLL divider. Larger values
mean the PLL operates at a faster rate. This register should be
loaded first whenever a change is needed. (This will give the PLL
more time to lock.)1
Bits [3:0] LSBs of the PLL divider word. Links to PLL MSB to make
a 12-bit register.1
Selects VCO frequency range.
Varies the current that drives the PLL loop filter.
ADC clock phase adjustment. Larger values mean more delay
(1 LSB = T/32).
Places the clamp signal an integer number of clock periods after
the trailing edge of Hsync.
Number of clock periods that the clamp signal is actively
clamping.
Sets the number of pixel clocks that HSOUT will remain active.
Controls the ADC input range (contrast) of the red channel.
Larger values give less contrast.
Controls the ADC input range (contrast) of the green channel.
Larger values give less contrast.
Controls the ADC input range (contrast) of the blue channel.
Larger values give less contrast.
Controls the dc offset (brightness) of the red channel.
Larger values decrease brightness.
Controls the dc offset (brightness) of the green channel.
Larger values decrease brightness.
Controls the dc offset (brightness) of the blue channel.
Larger values decrease brightness.
Sets how many pixel clocks to count before toggling high or low.
This should be set to some number greater than the maximum
Hsync or equalization pulsewidth.
Sets the voltage level of the sync-on-green slicer’s comparator.
0 = No override.
1 = User overrides, interface set by 0x0F, Bit 1.
0 = Analog interface active.
1 = Digital interface active.
This interface is selected only if Register 0x0F, Bit 2 is set to 1, or if
both interfaces are active.
0 = Polarity determined by chip.
1 = Polarity set by 0x10, Bit 6.
0 = Active low polarity.
1 = Active high polarity.
0 = Active high sync signal.
1 = Active low sync signal.
Rev. 0 | Page 23 of 40
AD9882A
Hexadecimal
Address
0x11
Read and
Write or
Read Only
R/W
Bit
4
Default
Value
***0 ****
3
**** 0***
2
**** *0**
1
**** **0*
0
**** ***0
7
0*** ****
Output Vsync
Polarity
Active Vsync
Override
Active Vsync
Select
Clamp Function
6
*0** ****
Red Clamp Select
5
**0* ****
4
***0 ****
Green Clamp
Select
Blue Clamp Select
3
**** 1***
Coast Select
2
**** *0**
Coast Polarity
Override
1
**** **1*
Input Coast
Polarity
Register Name
Active Hsync
Override
Active Hsync
Select
0x12
0x13
R/W
R/W
7–0
7–0
0000 0000
0000 0000
Precoast
Postcoast
0x14
R/W
7–6
11** ****
5
**1* ****
4
***0 ****
Output Drive
Select
Programmable
Bandwidth
DVI Clock Invert
3
**** 0***
2
**** *0**
DVI PDO ThreeState
HDCP Address
1
0
**** **1*
**** ***0
Power-Down
Enable 4:2:2
0x15
RO
7
4
Analog Hsync
Active
Analog SOG
Active
Analog Vsync
Active
DVI Active
3
Active Interface
6
5
Function
0 = No override.
1 = User overrides, analog Hsync set by 0x10, Bit 3.
0 = Analog Hsync from the Hsync input pin.
1 = Analog Hsync from SOG. This bit is used if Register 0x10, Bit 4
is set to 1 or if both syncs are active.
0 = Invert.
1 = Not inverted.
0 = No override.
1 = User overrides, analog Vsync set by 0x10, Bit 0.
0 = Analog Vsync from the Vsync input pin.
1 = Analog Vsync from sync separator.
0 = Clamping with internal clamp.
1 = Clamping disabled.
0 = Clamp to ground.
1 = Clamp to midscale for red channel.
0 = Clamp to ground.
1 = Clamp to midscale for green channel.
0 = Clamp to ground.
1 = Clamp to midscale for blue channel.
0 = Disabled coast.
1 = Coasting with internally generated coast signal.
0 = Coast polarity determined by the chip.
1 = Coast polarity set by 0x11, Bit 1. This bit must be set to 1 to
disable coast.
0 = Active low coast signal.
1 = Active high coast signal. This bit must be set to 1 to disable
coast.
Number of Hsync periods that coast goes active prior to Vsync.
Number of Hsync periods before coast goes inactive following
Vsync.
Selects among high, medium, and low output drive strength.
0 = Low bandwidth of 10 MHz.
1 = High bandwidth of 300 MHz.
0 = DVI data clock output not inverted.
1 = DVI data clock output inverted.
For digital interface only.
0 = Normal outputs.
1 = High impedance outputs.
Address Bit 0 = 0 for HDCP slave port.
Address Bit 1 = 1 for HDCP slave port.
0 = Full chip power-down.
0 = 4:4:4 mode.
1 = 4:2:2 mode.
0 = Hsync not detected.
1 = Hsync detected.
0 = Sync signal not detected on green channel.
1 = Sync signal detected on green channel.
0 = Vsync not detected.
1 = Vsync detected.
0 = Digital interface clock not detected.
1 = Digital interface clock detected.
0 = Analog interface active.
1 = DVI interface active.
Rev. 0 | Page 24 of 40
AD9882A
Hexadecimal
Address
0x16
Read and
Write or
Read Only
RO
Bit
7
Default
Value
6
Register Name
Active Hsync
Hsync Polarity
Detected
Active Vsync
5
4
Vsync Polarity
Detected
Coast Polarity
Detected
3
2
R/W
R/W
R/W
R/W
R/W
7–0
7–0
7–0
7–0
7
0000 0000
0000 000X
0000 010X
0011 1111
1*** ****
HDCP Keys
Detected
Test Register
Test Register
Test Register
Test Register
MDA and MCL
0x1C
R/W
6–0
7–1
0
*111 0000
0000 111*
**** ***1
Test Register
Test Register
RXC Connect
0x1D
0x1E
RO
RO
7–0
7–0
0x17
0x18
0x19
0x1A
0x1B
1
Test Register
Test Register
Function
0 = Hsync from the Hsync input pin.
1 = Hsync from the SOG input.
0 = Active low polarity detected.
1 = Active high polarity detected.
0 = Vsync from the Vsync input pin.
1 = Vsync from SOG.
0 = Active high polarity detected.
1 = Active low polarity detected.
0 = Active low polarity detected.
1 = Active high polarity detected.
This function works only with internal coast.
0 = Not detected.
1 = Detected.
Must be set to 1000 0000 for proper operation.
Must be set to 1100 000x for proper operation.
Must be set to 0111 110x for proper operation.
Must be set to default for proper operation.
0 = MDA and MCL three-stated.
1 = MDA and MCL not three-stated.
Must be set to *110 0111 for proper operation.
Must be set to default for proper operation.
0 = RX clock lines disconnected.
1 = RX clock lines connected.
Reserved for future use.
Reserved for future use.
The AD9882A updates the PLL divide ratio only when the LSBs are written to Register 0x02.
Rev. 0 | Page 25 of 40
AD9882A
2-WIRE SERIAL CONTROL REGISTER DETAIL
CHIP IDENTIFICATION
0x03 7–6
0x00 7–0
Two bits that establish the operating range of the clock
generator. VCORNGE must be set to correspond with the
desired operating frequency (incoming pixel rate).
Chip Revision
An 8-bit register that represents the silicon revision.
PLL DIVIDER CONTROL
0x01 7–0
PLL Divide Ratio MSBs
The eight most significant bits of the 12-bit PLL divide ratio
PLLDIV. (The operational divide ratio is PLLDIV + 1.)
The PLL derives a pixel clock from the incoming Hsync signal.
The pixel clock frequency is then divided by an integer value,
such that the output is phase-locked to Hsync. This PLLDIV
value determines the number of pixel times (pixels plus horizontal blanking overhead) per line. This is typically 20% to 30%
more than the number of active pixels in the display.
The 12-bit value of the PLL divider supports divide ratios from
221 to 4095. The higher the value loaded in this register, the
higher the resulting clock frequency with respect to a fixed
Hsync frequency.
VESA has established some standard timing specifications that
can assist in determining the value for PLLDIV as a function of
the horizontal and vertical display resolution and frame rate
(see Table 10). However, many computer systems do not conform precisely to the recommendations, and these numbers
should be used only as a guide. The display system manufacturer should provide automatic or manual means for
optimizing PLLDIV. An incorrectly set PLLDIV usually
produces one or more vertical noise bars on the display. The
greater the error, the greater the number of bars produced.
The power-up default value of PLLDIV is 1693
(PLLDIVM = 0x69, PLLDIVL = 0xDx).
The AD9882A updates the full divide ratio only when the LSBs
are changed. Writing to this register by itself does not trigger an
update.
0x02 7–4
PLL Divide Ratio LSBs
VCO Range Select
The PLL VCO gives the best jitter performance while operating
at high frequencies. For this reason, to output low pixel rates
and still get good jitter performance, the PLL VCO actually
operates at a higher frequency but then divides down the clock
rate afterward. Table 13 shows the pixel rates for each VCO
range setting. The PLL output divisor is automatically selected
with the VCO range setting.
Table 13. VCO Ranges
VCORNGE
00
01
10
Pixel Rate Range
12–41
41–82
82–140
The power-up default value is VCORNGE = 01.
0x03 5–3
CURRENT Charge Pump Current
Three bits that establish the current driving the loop filter in the
clock generator.
Table 14. Charge Pump Currents
Charge Pump
000
001
010
011
100
101
110
111
Current (µA)
50
100
150
250
350
500
750
1500
Charge pump must be set to correspond with the desired
operating frequency (incoming pixel rate). See Table 10 for
the charge pump current for each register setting.
The four least significant bits of the 12-bit PLL divide ratio
PLLDIV. The operational divide ratio is PLLDIV + 1.
The power-up default value for current is 001.
The power-up default value of PLLDIV is 1693
(PLLDIVM = 0x69, PLLDIVL = 0xDx).
A 5-bit value that adjusts the sampling phase in 32 steps across
one pixel time. Each step represents an 11.25° shift in sampling
phase.
The AD9882A updates the full divide ratio only when this
register is written.
The power-up default phase adjust value is 0x10.
0x04 7–3
Rev. 0 | Page 26 of 40
Phase Adjust
AD9882A
CLAMP TIMING
0x0A 7–0
0x05 7–0
An 8-bit word that sets the gain of the blue channel. See Red
gain (0x08).
Clamp Placement
An 8-bit register that sets the position of the internally
generated clamp.
Blue Gain
Blue Gain
INPUT OFFSET
When clamp function (Register 0x11, Bit 7) is 0, a clamp signal
is generated internally at a position established by the clamp
placement and for a duration set by the clamp duration.
Clamping is started (clamp placement) an integral number of
pixel periods after the trailing edge of Hsync. The clamp
placement can be programmed to any value from 1 to 255.
0x0B 7–1
Red Channel Offset Adjust
When clamp function is 1, this register is ignored.
A 7-bit offset binary word that sets the dc offset of the red channel. One LSB of offset adjustment equals approximately one LSB
change in the ADC offset. Therefore, the absolute magnitude of
the offset adjustment scales as the gain of the channel changes.
A nominal setting of 64 results in the channel nominally clamping the back porch (during the clamping interval) to Code 00.
An offset setting of 127 results in the channel clamping to
Code 63 of the ADC. An offset setting of 0 clamps to Code –64
(off the bottom of the range). Increasing the value of the red
offset decreases the brightness of the channel.
0x06 7–0
0x0C 7–1
The clamp should be placed during a time that the input signal
presents a stable black-level reference, usually the back porch
period between Hsync and the image.
Clamp Duration
A 7-bit offset binary word that sets the dc offset of the green
channel. See the 0x0B 7–1 red channel offset adjust.
An 8-bit register that sets the duration of the internally
generated clamp.
For the best results, the clamp duration should be set to include
the majority of the black-reference signal time that follows the
Hsync signal trailing edge. Insufficient clamping time can produce brightness changes at the top of the screen and a slow
recovery from large changes in the average picture level (APL)
or brightness.
When clamp function is 1, this register is ignored.
HSYNC OUTPUT PULSE WIDTH
0x07 7–0
Hsync Output Pulse Width
An 8-bit register that sets the duration of the Hsync output
pulse.
The leading edge of the Hsync output is triggered by the
internally generated, phase-adjusted PLL feedback clock. The
AD9882A then counts a number of pixel clocks equal to the
value in this register minus one. This triggers the trailing edge
of the Hsync output, which is also phase-adjusted.
INPUT GAIN
0x08 7–0
Red Gain
Red Gain
An 8-bit word that sets the gain of the red channel. The
AD9882A can accommodate input signals with a full-scale
range of between 0.5 V and 1.0 V p-p. Setting red gain to 255
corresponds to an input range of 1.0 V. A red gain of 0
establishes an input range of 0.5 V. Note that increasing red gain
results in the picture having less contrast (the input signal uses
fewer of the available converter codes). See Figure 4.
0x09 7–0
Green Gain
Green Channel Offset Adjust
0x0D 7–1
Blue Channel Offset Adjust
A 7-bit offset binary word that sets the dc offset of the blue
channel. 0x0B 7–1 Red channel offset adjust.
0x0E 7–0
Sync Separator Threshold
This register is used to set the responsiveness of the sync
separator. It sets how many internal 5 MHz clock periods the
sync separator must count to before toggling high or low. It
works like a low-pass filter to ignore Hsync pulses in order to
extract the Vsync signal. This register should be set to some
number greater than the maximum Hsync pulse width. Note
that the sync separator threshold uses an internal dedicated
clock with a frequency of approximately 5 MHz.
The default for this register is 0x20.
0x0F 7–3
Sync-on-Green Slicer Threshold
This register allows the comparator threshold of the sync-ongreen slicer to be adjusted. This register adjusts it in steps of
10 mV, with the minimum setting equaling 10 mV and the
maximum setting equaling 330 mV.
The default setting is 15 decimal and corresponds to a threshold
value of 170 mV.
0x0F 2
AIO Active Interface Override
This bit is used to override the automatic interface selection
(Bit 3 in Register 0x15). To override, set this bit to Logic 1.
When overriding, the active interface is set via Bit 1 in this
register.
Table 15. Active Interface Override Settings
Green Gain
An 8-bit word that sets the gain of the green channel. See red
gain (0x08).
AIO
0
1
Result
Autodetermines the active interface.
Override; Bit 1 determines the active interface.
The default for this register is 0.
Rev. 0 | Page 27 of 40
AD9882A
0x0F 1
AIS Active Interface Select
0x10 5
This bit is used under two conditions. It is used to select the
active interface when the override bit is set (Register 0x0F,
Bit 2). Alternatively, it is used to determine the active interface
when not overriding but both interfaces are detected.
Hsync Output Polarity
This bit determines the polarity of the Hsync output and the
SOG output. Table 19 shows the effect of this option. Sync
indicates the logic state of the sync pulse.
Table 19. Hsync Output Polarity Settings
Table 16. Active Interface Select Settings
AIS
0
1
Setting
0
1
Result
Analog interface
Digital interface
SYNC
Logic 1 (positive polarity)
Logic 0 (negative polarity)
The default setting for this register is 0.
The default for this register is 0.
0x10 4
0x10 7
Hsync Input Polarity Override
Active Hsync Override
This register is used to override the internal circuitry that
determines the polarity of the Hsync signal going into the PLL.
This bit is used to override the automatic Hsync selection. To
override, set this bit to Logic 1. When overriding, the active
Hsync is set via Bit 3 in this register.
Table 17. Hsync Input Polarity Override Settings
Table 20. Active Hsync Override Settings
Override Bit
0
1
Override
0
1
Result
Hsync polarity determined by chip.
Hsync polarity determined by Register 0x10,
Bit 6.
Result
Autodetermines the active Hsync.
Override; Bit 3 determines the active Hsync.
The default for this register is 0.
The default for Hsync polarity override is 0. (Polarity
determined by chip.)
0x10 3
Active Hsync Select
A bit that must be set to indicate the polarity of the Hsync
signal that is applied to the PLL Hsync input.
This bit is used under two conditions. It is used to select the
active Hsync when the override bit is set (Bit 4). Alternatively, it
is used to determine the active Hsync when not overriding, but
both Hsyncs are detected.
Table 18. Hsync Input Polarity Settings
Table 21. Active Hsync Select Settings
HSPOL
0
1
Select
0
1
0x10 6
HSPOL Hsync Input Polarity
Function
Active low
Active high
Active low means the leading edge of the Hsync pulse is
negative-going. All PLL timing is based on the leading edge
of Hsync, which is the falling edge. The rising edge is used to
time the internal clamping.
Active high means the leading edge of the Hsync pulse is
positive-going. This means that PLL timing is based on the
leading edge of Hsync, which is now the rising edge.
The device operates if this bit is set incorrectly, but the
internally generated clamp position, as established by clamp
placement (Register 0x05), is not placed as expected, which
might generate clamping errors.
The power-up default value for HSPOL is 1.
Result
Hsync input
Sync-on-green input
The default for this register is 0.
0x10 2
Vsync Output Polarity
This bit determines the polarity of the Vsync output. Table 22
shows the effect of this option. SYNC indicates the logic state of
the sync pulse.
Table 22. Vsync Output Polarity Settings
Setting
1
0
SYNC
Not inverted
Inverted
The default setting for this register is 0.
0x10 1
Active Vsync Override
This bit is used to override the automatic Vsync selection. To
override, set this bit to Logic 1. When overriding, the active
interface is set via Bit 0 in this register.
Rev. 0 | Page 28 of 40
AD9882A
Table 23. Active Vsync Override Settings
0x11 5
Override
0
1
This bit determines whether the green channel is clamped to
ground or to midscale.
Result
Autodetermines the active Vsync
Override; Bit 0 determines the
active Vsync.
The default for this register is 0.
0x10 0
Table 27. Green Clamp Select Settings
Clamp
0
1
Active Vsync Select
This bit is used to select the active Vsync when the override bit
is set (Bit 1).
Blue Clamp Select
This bit determines whether the blue channel is clamped to
ground or to midscale.
Result
Vsync input
Sync separator output
Table 28. Blue Clamp Select Settings
The default for this register is 0.
0x11 7
Function
Clamp to ground
Clamp to midscale (Pin 74)
The default setting for this register is 0.
0x11 4
Table 24. Active Vsync Select Settings
Select
0
1
Green Clamp Select
Clamp
0
1
Clamp Function
This bit enables/disables clamping.
Function
Clamp to ground
Clamp to midscale (Pin 74)
The default setting for this register is 0.
Table 25. Clamp Input Signal Source Settings
Clamp Function
0
1
0x11 3
Function
Internally generated clamp enabled
Clamping disabled
This bit is used to enable or disable the coast signal. If coast is
enabled, the additional decision of using the Vsync input pin
or the output from the sync separator needs to be made
(Register 0x10, Bits 1, 0). To disable coast, the user must set
Register 0x11, Bit 2 to 1 and Register 0x11, Bit 1 to 1.
0 enables the clamp timing circuitry controlled by clamp
placement and clamp duration. The clamp position and
duration is counted from the trailing edge of Hsync.
1 disables clamping. The three channels are clamped when the
clamp signal is active.
Power-up default value for clamp function is 0.
0x11 6
Red Clamp Select
A bit that determines whether the red channel is clamped to
ground or to midscale. For RGB video, all three channels are
referenced to ground. For YPbPr, the Y channel is referenced to
ground, but the PbPr channels are referenced to midscale.
Clamping to midscale clamps to Pin 74.
Table 26. Red Clamp Select Settings
Clamp
0
1
Function
Clamp to ground
Clamp to midscale (Pin 74)
The default setting for this register is 0.
Coast Select
Table 29. Coast Enable Settings
Select
0
1
Result
Coast disabled
Internally generated coast signal
The default for this register is 1.
0x11 2
Coast Input Polarity Override
This register is used to override the internal circuitry that
determines the polarity of the coast signal going into the PLL.
When disabling coast, Register 11, Bit 2 must be set to 1 and
Register 0x11, Bit 1 must be set to 1. This register works only
when coast is disabled. It does not work with internal coast.
Table 30. Coast Input Polarity Override Settings
Override Bit
0
1
Result
Coast polarity determined by chip
Coast polarity determined by user
The default for coast polarity override is 0.
Rev. 0 | Page 29 of 40
AD9882A
0x11 1 Coast Input Polarity
0x14 4
This bit indicates the polarity of the coast signal that is applied
to the PLL coast input.
This register can be used only when coast is disabled and
Register 0x11, Bit 2 is set to 1.
A control bit for the inversion of the output data clock (Pin 85).
This function works only for the digital interface. When not
inverted, data is output on the falling edge of the data clock. See
the Timing Diagrams sections, Figure 14 and Figure 15, to see
how this affects timing.
Table 31. Coast Input Polarity Settings
Table 34. Clock Output Invert Settings
CSTPOL
0
1
Clk Inv
0
1
Function
Active low
Active high
Clk Inv Data Output Clock Invert
Function
Not inverted
Inverted
The power-up default value is CSTPOL = 1.
The default for this register is 0 (not inverted).
0x12 7–0
0x14 3
Precoast
PDO Power-Down Outputs
This register allows the coast signal to be applied prior to the
Vsync signal. This is necessary in cases where pre-equalization
pulses are present. This register defines the number of edges
that are filtered before Vsync on a composite sync.
This bit is used to put the outputs in a high impedance mode.
This applies to the 24 data output pins, HSOUT, VSOUT, and
DE pins.
The default is 0.
Table 35. Power-Down Output Settings
0x13 7–0 Postcoast
This register allows the coast signal to be applied following the
Vsync signal. This is necessary in cases where postequalization
pulses are present. The step size for this control is one Hsync
period. This register defines the number of edges that are
filtered after Vsync on a composite sync.
PDO
0
1
Function
Normal operation
Three-state
The default for this register is 0. (This option works on both the
analog and digital interfaces.)
0x14 2
HDCP Address
The default is 0.
This bit is used to set the HDCP slave port address.
0x14 7–6 Output Drive
Table 36. HDCP Address Settings
These two bits select the drive strength for the high speed
digital outputs (all data output and clock output pins). Higher
drive strength results in faster rise/fall times, and in general
makes it easier to capture data. Lower drive strength results in
slower rise/fall times and helps reduce EMI and digitally
generated power supply noise.
Address Bit
0
1
Table 32. Output Drive Strength Settings
Bit 7
1
0
0
Bit 6
X
1
0
Result
High drive strength
Medium drive strength
Low drive strength
The default for this register is 11, high drive strength. This
option works on both the analog and digital interfaces.
0x14 5
Programmable Analog Bandwidth
The default for this register is 0.
0x14 1
PWRDN
This bit is used to control chip power-down. See the Power
Management section for details about which blocks are actually
powered down.
Table 37. Power-Down Settings
Select
0
1
The default for this register is 1.
These bits select the analog bandwidth.
Table 33. Analog Bandwidth Control
Bit 5
0
1
Result
0 for HDCP Slave Port
1 for HDCP Slave Port
Analog Bandwidth
10 MHz
300 MHz
Rev. 0 | Page 30 of 40
Result
Power-down
Normal operation
AD9882A
0x14 0
4:2:2 Output Mode Select
0x15 4
This bit configures the output data in 4:2:2 mode. This mode
can be used to reduce the number of data lines used from 24 to
16 for applications using YPbPr graphics signals. A timing
diagram for this mode is shown in Figure 17. Recommended
input and output configurations are shown in Table 39. In
4:2:2 mode, the red and blue channels can be interchanged to
help satisfy board layout or timing requirements, but the green
channel must be configured for Y.
Digital Interface Clock Detect
This bit is used to indicate when activity is detected on the
digital interface clock input.
Table 43. Digital Interface Clock Detection Results
Detect
0
1
Function
No activity detected
Activity detected
Figure 20 shows where this function is implemented.
Table 38. 4:2:2 Output Mode Select
Select
0
1
Output Mode
4:4:4
4:2:2
0x15 3
Table 39. 4:2:2 Input/Output Configuration
Channel
Red
Green
Blue
0x15 7
Input Connection
Pr
Y
Pr
Output Format
Pb/Pr
Y
High impedance
Hsync Detect
This bit is used to indicate when activity is detected on the
HSYNC input pin (Pin 79). If Hsync is held high or low, activity
is not detected.
Table 40. Hsync Detection Results
Active Interface
This bit is used to indicate which interface should be active,
analog or digital. It checks for activity on the analog interface
and for activity on the digital interface, then determines which
should be active according to Table 44. Specifically, analog
interface detection is determined by OR’ing Bits 7, 6, and 5 in
this register. Digital interface detection is determined by Bit 4 in
this register. If both interfaces are detected, the user can
determine which has priority via Bit 1 in Register 0x0F. The
user can override this function via Bit 2 in Register 0x0F. If the
override bit is set to Logic 1, then this bit will be forced to the
same state as Bit 1 in Register 0x0F.
Table 44. Active Interface Results
Bits 7, 6, or 5
(Analog
Detection)
0
Bit 4
(Digital
Detection)
0
Override
0
This bit is used to indicate when sync activity is detected on the
sync-on-green input pin (Pin 64).
0
1
1
X
1
0
1
X
0
0
0
1
Table 41. Sync-on-Green Detection Results
AI = 0 means analog interface. AI = 1 means digital interface.
The override bit is in Register 0x0F, Bit 2.
Detect
0
1
Function
No activity detected
Activity detected
Figure 20 shows where this function is implemented.
0x15 6
Detect
0
1
Sync-on-Green Detect
Function
No activity detected
Activity detected
0x16 7
Figure 20 shows where this function is implemented.
Note that if no sync signal is presented on the green video
input, normal video might still trigger activity.
0x15 5
Vsync Detect
This bit is used to indicate when activity is detected on the
Vsync input pin (Pin 80). If Vsync is held high or low, activity is
not detected.
AHS Active Hsync
This bit indicates which Hsync input source is being used by
the PLL (Hsync input or sync-on-green). Bits 6 and 7 in
Register 0x15 determine which source is used. If both Hsync
and SOG are detected, the user can determine which has
priority via Bit 3 in Register 0x10. The user can override this
function via Bit 4 in Register 0x10. If the override bit is set to
Logic 1, then this bit will be forced to the same state as Bit 3 in
Register 0x10.
Table 42. Vsync Detection Results
Detect
0
1
AI
Soft powerdown (seek
mode)
1
0
Bit 1 in 0x0F
Bit 1 in 0x0F
Function
No activity detected
Activity detected
Figure 20 shows where this function is implemented.
Rev. 0 | Page 31 of 40
AD9882A
0x16 3 Detected Coast Polarity Status
Table 45. Active Hsync Results
Hsync Detect
Register
0x15,Bit 7
0
SOG Detect
Register
0x,10 Bit 4
0
Override
Register
0x,15 Bit 6
0
0
1
1
1
0
1
0
0
0
X
X
1
AHS
Register
0x16,Bit 7
Bit 3 in
0x10
1
0
Bit 3 in
0x10
Bit 3 in
0x10
AHS = 0 means use the Hsync pin input for Hsync. AHS = 1
means use the SOG pin input for Hsync. The override bit is in
Register 0x10, Bit 4.
0x16 6
Detected Hsync Input Polarity Status
This bit reports the status of the Hsync input polarity detection
circuit. It can be used to determine the polarity of the Hsync
input. The detection circuit’s location is shown Figure 20.
Table 46. Detected Hsync Input Polarity Status
Hsync Polarity Status
0
1
0x16 5
Result
Hsync polarity is negative/active low.
Hsync polarity is positive/active high.
AVS Active Vsync
This bit indicates which Vsync source is being used for the
analog interface, the Vsync input or output from the sync
separator. If the override bit (0x10, Bit 1) is set to Logic 1, then
this bit will be forced to the same state as Bit 0 in Register 0x10.
Table 47. Active Vsync Results
Vsync Detect
Register
0x16 Bit 5
0
1
X
Override
Register
0x10 Bit 1
0
0
1
AVS
0
1
Bit 0 in 0x10
Hsync Polarity Status
0
1
0x16 2
Result
Coast polarity is negative/active low.
Coast polarity is positive/active high.
Key Read Verification
This bit reports wherever HDCP keys are detected.
Table 50. Key Read Verification
Detect
0
1
0x1B 7
Function
Not detected
Detected
MDA and MCL Three-State
The MDA and MCL three-state feature allows the EEPROM to
be programmed in-circuit. The MDA/MCL port must be threestated before attempting to program the EEPROM using an
external master. The keys are stored in an I2C compatible 3.3 V
serial EEPROM of at least 512 bytes. The EEPROM should have
a device address of 0xA0.
0x1C 0 RxC Connect
The RxC (DVI differential clock pair) can be disconnected via
software if the HDCP specified hot plug detect does not work to
resynchronize the HDCP transmitter engine. To use this
function, write this bit to 0 (0xR1C to 0x0E) then back to 1
(0xR1C to 0x0F). This signals to the DVI transmitter to restart
the HDCP protocol. It is recommended that the user perform
this toggle of the bit whenever switching from analog to digital
inputs.
Set
0
1
Function
RxC lines disconnected (open).
RxC lines connected internally.
2-WIRE SERIAL CONTROL PORT
Detected Vsync Output Polarity Status
This bit reports the status of the Vsync output polarity
detection circuit. It can be used to determine the polarity of the
Vsync output. The detection circuit’s location is shown in
Figure 20.
Table 48. Detected Vsync Input Polarity Status
Vsync Polarity Status
0
1
Table 49. Detected Coast Input Polarity Status
Table 51. DVI Clock Connect
AVS = 0 means Vsync input. AVS = 1 means sync separator.
The override bit is in Register 0x10, Bit 1.
0x16 4
This bit reports the status of the coast input polarity detection
circuit. The detection circuit’s location is shown in Figure 20.
This bit applies only to the internal coast and does not apply
when coast is disabled.
Result
Vsync polarity is active high.
Vsync polarity is active low.
A 2-wire serial control interface is provided. Two AD9882A
devices can be connected to the 2-wire serial interface, with
each device having a unique address.
The 2-wire serial interface comprises a clock (SCL) and a
bidirectional data (SDA) pin. The analog flat panel interface
acts as a slave for receiving and transmitting data over the serial
interface. When the serial interface is not active, the logic levels
on SCL and SDA are pulled high by external pull-up resistors.
Data received or transmitted on the SDA line must be stable for
the duration of the positive-going SCL pulse. Data on SDA must
Rev. 0 | Page 32 of 40
AD9882A
change only when SCL is low. If SDA changes state while SCL is
high, the serial interface interprets that action as a start or stop
sequence.
acknowledge the AD9882A during a read sequence, the
AD9882A interprets this as end of data. The SDA remains
high so the master can generate a stop signal.
The five components to serial bus operation are
Writing data to specific control registers of the AD9882A
requires that the 8-bit address of the control register of interest
be written after the slave address has been established. This
control register address is the base address for subsequent write
operations. The base address autoincrements by one for each
byte of data written after the data byte intended for the base
address. If there are more bytes transferred than there are available addresses, the address does not increment and remains at
its maximum value of 0x1E. Any base address higher than 0x1E
does not produce an acknowledge signal.
•
•
•
•
•
Start signal
Slave address byte
Base register address byte
Data byte to read or write
Stop signal
When the serial interface is inactive (SCL and SDA are high),
communications are initiated by sending a start signal. The start
signal is a high-to-low transition on SDA while SCL is high.
This signal alerts all slaved devices that a data transfer sequence
is coming.
Data is read from the control registers of the AD9882A in a
similar manner. Reading requires two data transfer operations:
The first eight bits of data transferred after a start signal comprise a 7-bit slave address (the first seven bits) and a single R/W
bit (the eighth bit). The R/W bit indicates the direction of data
transfer: read from (1) or write to (0) the slave device. If the
transmitted slave address matches the address of the device
(set by the state of the SA input pin listed in Table 52), the
AD9882A acknowledges by bringing SDA low on the ninth
SCL pulse. If the addresses do not match, the AD9882A does
not acknowledge.
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
A5
0
0
A4
0
0
A3
1
1
A2
1
1
A1
0
0
The base address must be written with the R/W bit of the
slave address byte low to set up a sequential read operation.
•
Reading (the R/W bit of the slave address byte high) begins
at the previously established base address. The address of
the read register autoincrements after each byte is
transferred.
To terminate a read/write sequence to the AD9882A, a stop
signal must be sent. A stop signal comprises a low-to-high
transition of SDA while SCL is high. The timing for the
read/write is shown in Figure 18, and a typical byte transfer is
shown in Figure 19.
Table 52. Serial Port Addresses
Bit 7
A6
(MSB)
1
1
•
Bit 1
A0
(LSB)
0
1
A repeated start signal occurs when the master device driving
the serial interface generates a start signal without first generating a stop signal to terminate the current communication.
This is used to change the mode of communication (read, write)
between the slave and master without releasing the serial
interface lines.
Data Transfer via Serial Interface
For each byte of data read or written, the MSB is the first bit of
the sequence. If the AD9882A does not acknowledge the master
device during a write sequence, the SDA remains high so the
master can gen-erate a stop signal. If the master device does not
SDA
tBUFF
tDHO
tSTAH
tDSU
tSTASU
tSTOSU
tDAL
05123-018
SCL
tDAH
Figure 18. Serial Port Read/Write Timing
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
ACK
05123-019
SDA
SCL
Figure 19. Serial Interface, Typical Byte Transfer
Rev. 0 | Page 33 of 40
AD9882A
Serial Interface Read/Write Examples
Example 1. Write to one control register
Example 3. Read from one control register
•
Start signal
•
Start signal
•
Slave address byte (R/W bit = LOW)
•
Slave address byte (R/W bit = LOW)
•
Base address byte
•
Base address byte
•
Data byte to base address
•
Start signal
•
Stop signal
•
Slave address byte (R/W bit = HIGH)
Example 2. Write to four consecutive control registers
•
Data byte from base address
•
Start signal
•
Stop signal
•
Slave address byte (R/W bit = LOW)
Example 4. Read from four consecutive control registers
•
Base address byte
•
Start signal
•
Data byte to base address
•
Slave address byte (R/W bit = LOW)
•
Data byte to (base address + 1)
•
Base address byte
•
Data byte to (base address + 2)
•
Start signal
•
Data byte to (base address + 3)
•
Slave address byte (R/W bit = HIGH)
•
Stop signal
•
Data byte from base address
•
Data byte from (base address + 1)
•
Data byte from (base address + 2)
•
Data byte from (base address + 3)
•
Stop signal
Table 53. Control of the Sync Block Muxes via the Serial Register
Mux Number(s)
1 and 2
Serial Bus Control Bit
0x10: Bit 3
3
0x10: Bit 0
4, 5, and 6
0x0F: Bit 1
Control Bit State
0
1
0
1
0
1
Rev. 0 | Page 34 of 40
Result
Pass Hsync
Pass sync-on-green
Pass Vsync
Pass sync separator signal
Pass analog interface signals
Pass digital interface signals
AD9882A
SYNC PROCESSING ENGINE
SYNC SLICER
The sync separator on the AD9882A is an 8-bit digital counter
with a 5 MHz clock. It works independently of the polarity of
the composite sync signal. Polarities are determined elsewhere
on the chip. The counter counts up when Hsync pulses are
present. But since Hsync pulses are relatively short in width, the
counter reaches only a value of N before the pulse ends. It then
starts counting down, eventually reaching 0 before the next
Hsync pulse arrives. The specific value of N varies for different
video modes, but is always less than 255. For example, with a
1 ms width Hsync, the counter only reaches 5 (1 µs/200 ns = 5).
When Vsync is present on the composite sync, the counter also
counts up. However, because the Vsync signal is much longer, it
counts to a higher number, M. For most video modes, M is at
least 255. So, Vsync can be detected on the composite sync
signal by detecting when the counter counts to higher than N.
The specific count that triggers detection (t) can be programmed through the serial register (0x0E).
This section describes the basic operation of the sync
processing engine (see Figure 20).
The purpose of the sync slicer is to extract the sync signal from
the green graphics channel. A sync signal is not present on all
graphics systems (only those with sync-on-green). The sync
signal is extracted from the green channel in a two-step process.
1.
SOG input is clamped to its negative peak (typically 0.3 V
below the black level).
2.
The signal goes to a comparator with a variable trigger
level, nominally 0.15 V above the clamped level. The
output signal is typically a composite sync signal
containing both Hsync and Vsync.
SYNC SEPARATOR
A sync separator extracts the Vsync signal from a composite
sync signal. It does this through a low-pass filter-like or
integrator-like operation. It works on the idea that the Vsync
signal stays active for a much longer time than the Hsync signal.
So, it rejects any signal shorter than a threshold value, which is
somewhere between an Hsync pulse width and a Vsync pulse
width.
Once Vsync has been detected, a similar process detects when it
goes inactive. At detection, the counter first resets to 0, then
starts counting up when Vsync goes away. In a way similar to
the previous case, it detects the absence of Vsync when the
counter reaches the threshold count (T). In this way, it rejects
noise and/or serration pulses. Once Vsync is determined to be
absent, the counter resets to 0 and begins the cycle again.
ACTIVITY
DETECT
SYNC STRIPPER
NEGATIVE
PEAK
CLAMP
SYNC SEPARATOR
COMP
SYNC
AD9882A
INTEGRATOR
VSYNC
1/S
SOG
MUX 1
HSYNC IN
SOG OUT
ACTIVITY
DETECT
PLL
MUX 4
POLARITY
DETECT
HSYNC OUT
HSYNC
MUX 2
CLOCK
GENERATOR
COAST
PIXEL CLOCK
HSYNC OUT
POLARITY
DETECT
MUX 5
VSYNC IN
VSYNC OUT
MUX 3
HSYNC
DVI
DE
Figure 20. Sync Processing Block Diagram
Rev. 0 | Page 35 of 40
MUX 6
VSYNC
DE
05123-020
ACTIVITY
DETECT
AD9882A
PCB LAYOUT RECOMMENDATIONS
The AD9882A is a high precision, high speed analog device. To
derive the maximum performance from the part, it is important
to have a well laid out board. The following is a guide for
designing a board using the AD9882A.
ANALOG INTERFACE INPUTS
Using the following layout techniques on the graphics inputs is
extremely important.
Minimize the trace length running into the graphics inputs.
This is accomplished by placing the AD9882A as close as
possible to the graphics VGA connector. Long input trace
lengths are undesirable because they will pick up more noise
from the board and other external sources.
Place the 75 Ω termination resistors (see Figure 9) as close to
the AD9882A chip as possible. Any additional trace length
between the termination resistors and the input of the
AD9882A increases the magnitude of reflections, which
corrupts the graphics signal.
Use 75 Ω matched impedance traces. Trace impedances other
than 75 Ω also increase the chance of reflections.
The AD9882A has a very high input bandwidth (300 MHz).
While this is desirable for acquiring a high resolution PC
graphics signal with fast edges, it means that it captures any
high frequency noise present. Therefore, it is important to
reduce the amount of noise that gets coupled to the inputs.
Avoid running any digital traces near the analog inputs.
Due to the high bandwidth of the AD9882A, sometimes lowpass filtering the analog inputs can help to reduce noise. (For
many applications, filtering is unnecessary.) Experiments have
shown that placing a series ferrite bead prior to the 75 Ω
termination resistor is helpful in filtering out excess noise.
Specifically, the part used was the #2508051217Z0 from FairRite, but different applications may work best with different
bead values. Alternatively, placing a 100 Ω to 120 Ω resistor
between the 75 Ω termination resistor and the input coupling
capacitor can also be beneficial.
DIGITAL INTERFACE INPUTS
Many of the same techniques that are recommended for the
analog interface inputs should also be used for the digital
interface inputs. It is important to minimize trace lengths, then
make the input trace impedances match the input termination
(typically 50 Ω). Each differential input pair (RX0+, RX0–, RXC+,
RXC–, and so on) should be routed together using 50 Ω strip line
routing techniques and should be kept as short as possible. No
other components, such as clamping diodes, should be placed
on these inputs. Every effort should be made to route these
signals on a single layer (component layer) with no vias.
POWER SUPPLY BYPASSING
Bypassing each power supply pin with a 0.1 µF capacitor is
recommended. The exception is when two or more supply pins
are adjacent to each other. For these groupings of powers/
grounds, it is necessary to have one bypass capacitor. The
fundamental idea is to have a bypass capacitor within about 0.5
cm of each power pin. Also, avoid placing the capacitor on the
side of the PC board opposite the AD9882A, as that interposes
resistive vias in the path.
The bypass capacitors should be physically located between the
power plane and the power pin. Current should flow from the
power plane ->to the capacitor ->to the power pin. Do not
make the power connection between the capacitor and the
power pin. Placing a via underneath the capacitor pads, down
to the power plane, is generally the best approach.
It is particularly important to maintain low noise and good
stability of PVD (the clock generator supply). Abrupt changes in
PVD can result in similarly abrupt changes in sampling clock
phase and frequency. This can be avoided by careful attention to
regulation, filtering, and bypassing. It is highly desirable to
provide separate regulated supplies for each of the analog
circuitry groups (VD and PVD).
Some graphic controllers use levels of power when active
(during active picture time) that are substantially different from
those used when they are idle (during horizontal and vertical
sync periods). This can result in a measurable change in the
voltage supplied to the analog supply regulator, which can in
turn produce changes in the regulated analog supply voltage.
This can be mitigated by regulating the analog supply, or at least
PVD, from a different, cleaner, power source (for example, from
a 12 V supply).
Using a single ground plane for the entire board is also recommended. Experience has repeatedly shown that the noise
performance is the same or better with a single ground plane.
Using multiple ground planes can be detrimental, because each
separate ground plane is smaller than one common ground
plane, and can result in long ground loops.
In some cases, using separate ground planes is unavoidable.
When they must be used, it is recommended that at least a
single ground plane be placed under the AD9882A. The
location of the split should be at the receiver of the digital
outputs. In this case, it is even more important to place
components wisely, because the current loops are much longer
(current takes the path of least resistance). The following is an
example of a current loop: power plane -> AD9882A -> digital
output trace -> digital data receiver -> digital ground plane ->
analog ground plane.
Rev. 0 | Page 36 of 40
AD9882A
PLL
Place the PLL loop filter components as close to the FILT pin as
possible.
by adjusting Register 0x14. If series resistors are used, place
them as close as possible to the AD9882A pins but avoid adding
vias or extra length to the output trace to get the resistors closer.
Use the values suggested in the data sheet with 10% or smaller
tolerances.
If possible, limit the capacitance that each of the digital outputs
drives to less than 10 pF by keeping traces short and connecting
the outputs to only one device. Loading the outputs with
excessive capacitance increases the current transients inside the
AD9882A, creating more digital noise on its power supplies.
OUTPUTS: DATA AND CLOCKS
DIGITAL INPUTS
Try to minimize the trace length that the digital outputs have to
drive. Longer traces have higher capacitance and require more
current, which causes more internal digital noise.
The digital inputs on the AD9882A were designed to work with
3.3 V signals, but are tolerant of 5.0 V signals. No extra
components need to be added, if 5.0 V logic is used.
Shorter traces reduce the possibility of reflections.
Any noise that gets onto the Hsync input trace adds jitter to the
system. Therefore, minimize the trace length and do not run
any digital or other high frequency traces near it.
Do not place any digital or other high frequency traces near
these components.
Adding a series resistor with a value of 22 Ω to 100 Ω can
suppress reflections, reduce EMI, and reduce the current spikes
inside of the AD9882A. However, if 50 Ω traces are used on the
PCB, the data output should not need these resistors.
A 22 Ω resistor on the DATACK output should provide good
impedance matching that can reduce reflections. If EMI or
current spiking is a concern, use a lower drive strength setting
VOLTAGE REFERENCE
Bypass with a 0.1 µF capacitor. Place as close as possible to the
AD9882A pin. Make the ground connection as short as
possible.
Rev. 0 | Page 37 of 40
AD9882A
OUTLINE DIMENSIONS
16.00 BSC SQ
1.60 MAX
0.75
0.60
0.45
SEATING
PLANE
14.00 BSC SQ
12°
TYP
100
1
76
75
PIN 1
12.00
REF
TOP VIEW
(PINS DOWN)
10°
6°
2°
1.45
1.40
1.35
0.15
0.05
SEATING
PLANE
0.20
0.09
VIEW A
7°
3.5°
0°
0.08 MAX
COPLANARITY
25
51
50
26
0.50 BSC
VIEW A
0.27
0.22
0.17
ROTATED 90° CCW
COMPLIANT TO JEDEC STANDARDS MS-026BED
Figure 21. 100-Lead Quad Flatpack [LQFP]
(ST-100)
Dimensions shown in millimeters
ORDERING GUIDE
Model
AD9882AKSTZ-1001
AD9882AKSTZ-1401
AD9882A/PCB
1
Temperature Range
0°C to 70°C
0°C to 70°C
Z = Pb-free part.
Rev. 0 | Page 38 of 40
Package Option
ST-100
ST-100
Evaluation Kit
AD9882A
NOTES
Rev. 0 | Page 39 of 40
AD9882A
NOTES
Purchase of licensed I2C components of Analog Devices or one of its sublicensed Associated Companies conveys a license for the
purchaser under the Philips I2C Patent Rights to use these components in an I2C system, provided that the system conforms to the I2C
Standard Specification as defined by Philips.
© 2004 Analog Devices, Inc. All rights reserved. Trademarks and registered
trademarks are the property of their respective owners.
D05123-0-10/04(0)
Rev. 0 | Page 40 of 40