AD8196 2:1 HDMI/DVI Switch with Equalization

AD8196 2:1 HDMI/DVI Switch with Equalization
2:1 HDMI/DVI Switch with Equalization
AD8196
FEATURES
FUNCTIONAL BLOCK DIAGRAM
RESET
SERIAL INTERFACE
AVCC
DVCC
AMUXVCC
AVEE
DVEE
AD8196
I2C_SDA
I2C_SCL
I2C_ADDR
CONFIG
INTERFACE
CONTROL
LOGIC
VTTI
VTTO
+
IP_B[3:0]
IN_B[3:0]
4
–
4
+
4
+
4
SWITCH
CORE
PE
EQ
4
–
OP[3:0]
ON[3:0]
4
–
HIGH SPEED
VTTI
AUX_A[3:0]
4
4
AUX_B[3:0]
BUFFERED
SWITCH
CORE
LOW SPEED
4
AUX_COM[3:0]
UNBUFFERED
06470-001
IP_A[3:0]
IN_A[3:0]
BIDIRECTIONAL
Figure 1.
TYPICAL APPLICATION
HDTV SET
HDMI
RECEIVER
SET-TOP BOX
DVD PLAYER
AD8196
01:18
06470-002
Two inputs, one output HDMI™/DVI links
Enables HDMI 1.3-compliant receiver
Pin-to-pin compatible with the AD8190
Four TMDS™ channels per link
Supports 250 Mbps to 2.25 Gbps data rates
Supports 25 MHz to 225 MHz pixel clocks
Equalized inputs for operation with long HDMI cables
(20 meters at 2.25 Gbps)
Fully buffered unidirectional inputs/outputs
Globally switchable, 50 Ω on-chip terminations
Pre-emphasized outputs
Low added jitter
Single-supply operation (3.3 V)
Four auxiliary channels per link
Bidirectional unbuffered inputs/outputs
Flexible supply operation (3.3 V to 5 V)
HDCP standard compatible
Allows switching of DDC bus and two additional signals
Output disable feature
Reduced power dissipation
Output termination removal
Two AD8196s support HDMI/DVI dual-link
Standards compliant: HDMI receiver, HDCP, DVI
Serial (I2C® slave) control interface
56-lead, 8 mm x 8 mm, LFCSP, Pb-free package
Figure 2. Typical AD8196 Application for HDTV Sets
APPLICATIONS
Multiple input displays
Projectors
A/V receivers
Set-top boxes
Advanced television (HDTV) sets
GENERAL DESCRIPTION
PRODUCT HIGHLIGHTS
The AD8196 is an HDMI/DVI switch featuring equalized
TMDS inputs and pre-emphasized TMDS outputs, ideal for
systems with long cable runs. Outputs can be set to a high
impedance state to reduce the power dissipation and/or allow
the construction of larger arrays using the wire-OR technique.
1.
Supports data rates up to 2.25 Gbps, enabling greater than
1080p deep color (12-bit color) HDMI formats, and greater
than UXGA (1600 × 1200) DVI resolutions.
2.
Input cable equalizer enables use of long cables at the
input (more than 20 meters of 24 AWG cable at 2.25 Gbps).
3.
Auxiliary switch allows routing of the DDC bus and two
additional single-ended signals for a single chip, HDMI 1.3
receive-compliant solution.
The AD8196 is provided in a space-saving, 56-lead, LFCSP,
surface-mount, Pb-free, plastic package and is specified to
operate over the −40°C to +85°C temperature range.
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: 781.461.3113
©2007 Analog Devices, Inc. All rights reserved.
AD8196* PRODUCT PAGE QUICK LINKS
Last Content Update: 02/23/2017
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• AD8196: 2:1 HDMI/DVI Switch with Equalization Data
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AD8196
TABLE OF CONTENTS
Features .............................................................................................. 1
Serial Control Interface ................................................................. 14
Applications....................................................................................... 1
Reset ............................................................................................. 14
Functional Block Diagram .............................................................. 1
Write Procedure.......................................................................... 14
Typical Application........................................................................... 1
Read Procedure........................................................................... 15
General Description ......................................................................... 1
Switching/Update Delay............................................................ 15
Product Highlights ........................................................................... 1
Configuration Registers................................................................. 16
Revision History ............................................................................... 2
High Speed Device Modes Register......................................... 16
Specifications..................................................................................... 3
Auxiliary Device Modes Register............................................. 16
Absolute Maximum Ratings............................................................ 5
Receiver Settings Register ......................................................... 17
Thermal Resistance ...................................................................... 5
Input Termination Pulse Register ............................................ 17
Maximum Power Dissipation ..................................................... 5
Receive Equalizer Register ........................................................ 17
ESD Caution.................................................................................. 5
Transmitter Settings Register.................................................... 17
Pin Configuration and Function Descriptions............................. 6
Application Notes ........................................................................... 18
Typical Performance Characteristics ............................................. 8
Pinout........................................................................................... 18
Theory of Operation ...................................................................... 12
Cable Lengths and Equalization............................................... 19
Introduction ................................................................................ 12
The AD8196 as a Single-Channel Buffer ................................ 19
Input Channels............................................................................ 12
PCB Layout Guidelines.............................................................. 19
Output Channels ........................................................................ 12
Outline Dimensions ....................................................................... 23
Switching Mode .......................................................................... 13
Ordering Guide .......................................................................... 23
Auxiliary Lines Switching.......................................................... 13
REVISION HISTORY
1/07—Revision 0: Initial Version
Rev. 0 | Page 2 of 24
AD8196
SPECIFICATIONS
TA = 27°C, AVCC = 3.3 V, VTTI = 3.3 V, VTTO = 3.3 V, DVCC = 3.3 V, AMUXVCC = 5 V, AVEE = 0 V, DVEE = 0 V, differential input swing =
1000 mV, TMDS outputs terminated with external 50 Ω resistors to 3.3 V, unless otherwise noted.
Table 1.
Parameter
DYNAMIC PERFORMANCE
Maximum Data Rate (DR) per Channel
Bit Error Rate (BER)
Added Deterministic Jitter
Added Random Jitter
Differential Intrapair Skew
Differential Interpair Skew 1
EQUALIZATION PERFORMANCE
Receiver (Highest Setting) 2
Transmitter (Highest Setting) 3
INPUT CHARACTERISTICS
Input Voltage Swing
Input Common-Mode Voltage (VICM)
OUTPUT CHARACTERISTICS
High Voltage Level
Low Voltage Level
Rise/Fall Time (20% to 80%)
INPUT TERMINATION
Resistance
AUXILIARY CHANNELS
On Resistance, RAUX
On Capacitance, CAUX
Input/Output Voltage Range
POWER SUPPLY
AVCC
QUIESCENT CURRENT
AVCC
VTTI
VTTO
Conditions/Comments
Min
NRZ
PRBS 223 − 1
DR ≤ 2.25 Gbps, PRBS 27 − 1, EQ = 12 dB
2.25
Max
Unit
Gbps
10−9
At output
At output
25
1
1
40
ps (p-p)
ps (rms)
ps
ps
Boost frequency = 825 MHz
Boost frequency = 825 MHz
12
6
dB
dB
Differential
150
AVCC − 800
1200
AVCC
mV
mV
Single-ended high speed channel
Single-ended high speed channel
AVCC − 10
AVCC − 600
75
AVCC + 10
AVCC − 400
200
mV
mV
ps
135
Single-ended
50
Ω
DC bias = 2.5 V, ac voltage = 3.5 V, f = 100 kHz
100
8
AMUXVCC
Ω
pF
V
DVEE
Operating range
3
3.3
3.6
V
Outputs disabled
Outputs enabled, no pre-emphasis
Outputs enabled, maximum pre-emphasis
Input termination on 4
Output termination on, no pre-emphasis
Output termination on, maximum
pre-emphasis
30
53
98
5
36
73
40
60
108
40
40
80
45
66
120
54
44
88
mA
mA
mA
mA
mA
mA
4
7
0.01
10
0.1
mA
mA
115
411
754
271
574
936
364
664
1057
mW
mW
mW
200
1.5
ms
μs
ns
DVCC
AMUXVCC
POWER DISSIPATION
Outputs disabled
Outputs enabled, no pre-emphasis
Outputs enabled, maximum pre-emphasis
TIMING CHARACTERISTICS
Switching/Update Delay
Typ
High speed switching register: HS_CH
All other configuration registers
50
RESET Pulse Width
Rev. 0 | Page 3 of 24
AD8196
Parameter
SERIAL CONTROL INTERFACE 5
Input High Voltage, VIH
Input Low Voltage, VIL
Output High Voltage, VOH
Output Low Voltage, VOL
Conditions/Comments
Min
Typ
Max
2
0.8
2.4
0.4
1
Unit
V
V
V
V
Differential interpair skew is measured between the TMDS pairs of a single link.
AD8196 output meets the transmitter eye diagram as defined in the DVI Standard Revision 1.0 and the HDMI Standard Revision 1.3.
Cable output meets the receiver eye diagram mask as defined in the DVI Standard Revision 1.0 and the HDMI Standard Revision 1.3.
4
Typical value assumes only the selected HDMI/DVI link is active with nominal signal swings and that the unselected HDMI/DVI link is deactivated. Minimum and
maximum limits are measured at the respective extremes of input termination resistance and input voltage swing.
5
The AD8196 is an I2C slave and its serial control interface is based on the 3.3 V I2C bus specification.
2
3
Rev. 0 | Page 4 of 24
AD8196
ABSOLUTE MAXIMUM RATINGS
THERMAL RESISTANCE
Table 2.
Parameter
AVCC to AVEE
DVCC to DVEE
DVEE to AVEE
VTTI
VTTO
AMUXVCC
Internal Power Dissipation
High Speed Input Voltage
High Speed Differential
Input Voltage
Low Speed Input Voltage
I2C Logic Input Voltage
Storage Temperature
Range
Operating Temperature
Range
Junction Temperature
Rating
3.7 V
3.7 V
±0.3 V
AVCC + 0.6 V
AVCC + 0.6 V
5.5 V
4.62 W
AVCC − 1.4 V < VIN < AVCC + 0.6 V
2.0 V
θJA is specified for the worst-case conditions: a device soldered
in a 4-layer JEDEC circuit board for surface-mount packages.
θJC is specified for the exposed pad soldered to the circuit board
with no airflow.
DVEE − 0.3 V < VIN < AMUXVCC + 0.6 V
DVEE − 0.3 V < VIN < DVCC + 0.6 V
−65°C to +125°C
The maximum power that can be safely dissipated by the
AD8196 is limited by the associated rise in junction temperature. The maximum safe junction temperature for plastic
encapsulated devices is determined by the glass transition
temperature of the plastic, approximately 150°C. Temporarily
exceeding this limit may cause a shift in parametric performance
due to a change in the stresses exerted on the die by the package.
Exceeding a junction temperature of 175°C for an extended
period can result in device failure. To ensure proper operation,
it is necessary to observe the maximum power derating as
determined by the coefficients in Table 3.
Table 3. Thermal Resistance
Package Type
56-Lead LFCSP
θJA
27
θJC
2.1
Unit
°C/W
MAXIMUM POWER DISSIPATION
−40°C to +85°C
150°C
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
ESD CAUTION
Rev. 0 | Page 5 of 24
AD8196
56
55
54
53
52
51
50
49
48
47
46
45
44
43
AUX_A0
AUX_A1
AUX_A2
AUX_A3
DVEE
AUX_COM0
AUX_COM1
AUX_COM2
AUX_COM3
AMUXVCC
AUX_B0
AUX_B1
AUX_B2
AUX_B3
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
1
2
3
4
5
6
7
8
9
10
11
12
13
14
PIN 1
INDICATOR
AD8196
TOP VIEW
(Not to Scale)
42
41
40
39
38
37
36
35
34
33
32
31
30
29
AVCC
IP_B3
IN_B3
AVEE
IP_B2
IN_B2
VTTI
IP_B1
IN_B1
AVCC
IP_B0
IN_B0
AVEE
I2C_SDA
NOTES
1. THE AD8196 LFCSP HAS AN EXPOSED PADDLE (ePAD) ON THE UNDERSIDE
OF THE PACKAGE WHICH AIDS IN HEAT DISSIPATION. THE ePAD MUST BE
ELECTRICALLY CONNECTED TO THE AVEE SUPPLY PLANE IN ORDER TO
MEET THERMAL SPECIFICATIONS.
06470-003
DVCC
ON0
OP0
VTTO
ON1
OP1
DVCC
ON2
OP2
VTTO
ON3
OP3
RESET
I2C_SCL
15
16
17
18
19
20
21
22
23
24
25
26
27
28
AVCC
IN_A0
IP_A0
AVEE
IN_A1
IP_A1
VTTI
IN_A2
IP_A2
AVCC
IN_A3
IP_A3
AVEE
I2C_ADDR
Figure 3. Pin Configuration
Table 4. Pin Function Descriptions
Pin No.
1, 10, 33, 42
2
3
4, 13, 30, 39, ePAD
5
6
7, 36
8
9
11
12
14
15, 21
16
17
18, 24
19
20
22
23
25
26
27
28
29
31
32
Mnemonic
AVCC
IN_A0
IP_A0
AVEE
IN_A1
IP_A1
VTTI
IN_A2
IP_A2
IN_A3
IP_A3
I2C_ADDR
DVCC
ON0
OP0
VTTO
ON1
OP1
ON2
OP2
ON3
OP3
RESET
I2C_SCL
I2C_SDA
IN_B0
IP_B0
EE
AA
EA
Type 1
Power
HS I
HS I
Power
HS I
HS I
Power
HS I
HS I
HS I
HS I
Control
Power
HS O
HS O
Power
HS O
HS O
HS O
HS O
HS O
HS O
Control
Control
Control
HS I
HS I
Description
Positive Analog Supply. 3.3 V nominal.
High Speed Input Complement.
High Speed Input.
Negative Analog Supply. 0 V nominal.
High Speed Input Complement.
High Speed Input.
Input Termination Supply. Nominally connected to AVCC.
High Speed Input Complement.
High Speed Input.
High Speed Input Complement.
High Speed Input.
I2C Address LSB.
Positive Digital Power Supply. 3.3 V nominal.
High Speed Output Complement.
High Speed Output.
Output Termination Supply. Nominally connected to AVCC.
High Speed Output Complement.
High Speed Output.
High Speed Output Complement.
High Speed Output.
High Speed Output Complement.
High Speed Output.
Configuration Registers Reset. This pin is normally pulled up to DVCC.
I2C Clock.
I2C Data.
High Speed Input Complement.
High Speed Input.
Rev. 0 | Page 6 of 24
AD8196
Pin No.
34
35
37
38
40
41
43
44
45
46
47
48
49
50
51
52
53
54
55
56
1
Mnemonic
IN_B1
IP_B1
IN_B2
IP_B2
IN_B3
IP_B3
AUX_B3
AUX_B2
AUX_B1
AUX_B0
AMUXVCC
AUX_COM3
AUX_COM2
AUX_COM1
AUX_COM0
DVEE
AUX_A3
AUX_A2
AUX_A1
AUX_A0
Type 1
HS I
HS I
HS I
HS I
HS I
HS I
LS I/O
LS I/O
LS I/O
LS I/O
Power
LS I/O
LS I/O
LS I/O
LS I/O
Power
LS I/O
LS I/O
LS I/O
LS I/O
Description
High Speed Input Complement.
High Speed Input.
High Speed Input Complement.
High Speed Input.
High Speed Input Complement.
High Speed Input.
Low Speed Input/Output.
Low Speed Input/Output.
Low Speed Input/Output.
Low Speed Input/Output.
Positive Auxiliary Switch Supply. 5 V typical.
Low Speed Common Input/Output.
Low Speed Common Input/Output.
Low Speed Common Input/Output.
Low Speed Common Input/Output.
Negative Digital and Auxiliary Switch Power Supply. 0 V nominal.
Low Speed Input/Output.
Low Speed Input/Output.
Low Speed Input/Output.
Low Speed Input/Output.
HS = high speed, LS = low speed, I = input, O = output.
Rev. 0 | Page 7 of 24
AD8196
TYPICAL PERFORMANCE CHARACTERISTICS
TA = 27°C, AVCC = 3.3 V, VTTI = 3.3 V, VTTO = 3.3 V, DVCC = 3.3 V, AMUXVCC = 5 V, AVEE = 0 V, DVEE = 0 V, differential input swing =
1000 mV, TMDS outputs terminated with external 50 Ω resistors to 3.3 V, pattern = PRBS 27 − 1, data rate = 2.25 Gbps, unless otherwise noted.
HDMI CABLE
AD8196
DIGITAL
PATTERN
GENERATOR
SERIAL DATA
ANALYZER
EVALUATION
BOARD
REFERENCE EYE DIAGRAM AT TP1
TP1
TP2
TP3
06470-004
SMA COAX CABLE
06470-007
250mV/DIV
06470-005
250mV/DIV
Figure 4. Test Circuit Diagram for RX Eye Diagrams
06470-008
06470-006
250mV/DIV
0.125UI/DIV AT 2.25Gbps
Figure 7. RX Eye Diagram at TP3, EQ = 6 dB (Cable = 2 m, 30 AWG)
250mV/DIV
0.125UI/DIV AT 2.25Gbps
Figure 5. RX Eye Diagram at TP2 (Cable = 2 m, 30 AWG)
0.125UI/DIV AT 2.25Gbps
0.125UI/DIV AT 2.25Gbps
Figure 6. RX Eye Diagram at TP2 (Cable = 20 m, 24 AWG)
Figure 8. RX Eye Diagram at TP3, EQ = 12 dB (Cable = 20 m, 24 AWG)
Rev. 0 | Page 8 of 24
AD8196
TA = 27°C, AVCC = 3.3 V, VTTI = 3.3 V, VTTO = 3.3 V, DVCC = 3.3 V, AMUXVCC = 5 V, AVEE = 0 V, DVEE = 0 V, differential input swing =
1000 mV, TMDS outputs terminated with external 50 Ω resistors to 3.3 V, pattern = PRBS 27 − 1, data rate = 2.25 Gbps, unless otherwise noted.
HDMI CABLE
AD8196
DIGITAL
PATTERN
GENERATOR
SERIAL DATA
ANALYZER
EVALUATION
BOARD
REFERENCE EYE DIAGRAM AT TP1
TP1
TP2
TP3
06470-009
SMA COAX CABLE
06470-012
250mV/DIV
06470-010
250mV/DIV
Figure 9. Test Circuit Diagram for TX Eye Diagram
06470-013
06470-011
250mV/DIV
0.125UI/DIV AT 2.25Gbps
Figure 12. TX Eye Diagram at TP3, PE = 2 dB (Cable = 2 m, 30 AWG)
250mV/DIV
0.125UI/DIV AT 2.25Gbps
Figure 10. TX Eye Diagram at TP2, PE = 2 dB
0.125UI/DIV AT 2.25Gbps
0.125UI/DIV AT 2.25Gbps
Figure 11. TX Eye Diagram at TP2, PE = 6 dB
Figure 13. TX Eye Diagram at TP3, PE = 6 dB (Cable = 10 m, 28 AWG)
Rev. 0 | Page 9 of 24
AD8196
TA = 27°C, AVCC = 3.3 V, VTTI = 3.3 V, VTTO = 3.3 V, DVCC = 3.3 V, AMUXVCC = 5 V, AVEE = 0 V, DVEE = 0 V, differential input swing =
1000 mV, TMDS outputs terminated with external 50 Ω resistors to 3.3 V, pattern = PRBS 27 − 1, data rate = 2.25 Gbps, unless otherwise noted.
0.6
0.6
2m CABLE = 30AWG
5m TO 20m CABLES = 24AWG
2m CABLE = 30AWG
5m TO 20m CABLES = 24AWG
0.5
0.4
DETERMINISTIC JITTER (UI)
2.25Gbps
EQ = 12dB
0.3
1.65Gbps
EQ = 6dB
2.25Gbps
EQ = 6dB
0.2
1.65Gbps
EQ = 12dB
0.1
1.65Gbps, PE OFF
0.3
2.25Gbps, PE OFF
2.25Gbps, PE MAX
0.2
0.1
1.65Gbps, PE MAX
06470-014
0
0.4
0
5
10
15
0
25
20
0
5
HDMI CABLE LENGTH (m)
10
06470-017
DETERMINISTIC JITTER (UI)
0.5
20
15
HDMI CABLE LENGTH (m)
Figure 14. Jitter vs. Input Cable Length (See Figure 4 for Test Setup)
Figure 17. Jitter vs. Output Cable Length (See Figure 9 for Test Setup)
50
1200
45
1000
1080p
8-BIT
30
1080p
12-BIT
1.65Gbps
25
480p
20
1080i/720p
DJ (p-p)
480i
15
10
600
400
RJ (rms)
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
06470-015
200
5
0
800
0
2.4
06470-018
JITTER (ps)
35
EYE HEIGHT (mV)
40
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
3.5
3.6
DATA RATE (Gbps)
DATA RATE (Gbps)
Figure 15. Jitter vs. Data Rate
Figure 18. Eye Height vs. Data Rate
50
800
45
700
40
600
EYE HEIGHT (mV)
30
25
DJ (p-p)
20
15
500
400
300
200
10
0
3.0
RJ (rms)
3.1
3.2
3.3
3.4
3.5
3.6
SUPPLY VOLTAGE (V)
100
0
2.5
06470-019
5
06470-016
JITTER (ps)
35
2.6
2.7
2.8
2.9
3.0
3.1
3.2
3.3
SUPPLY VOLTAGE (V)
Figure 16. Jitter vs. Supply Voltage
Figure 19. Eye Height vs. Supply Voltage
Rev. 0 | Page 10 of 24
3.4
AD8196
50
50
40
40
30
30
JITTER (ps)
DJ (p-p)
20
10
06470-020
10
RJ (rms)
0
DJ (p-p)
20
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
RJ (rms)
0
2.5
2.0
2.7
Figure 20. Jitter vs. Differential Input Swing
3.5
3.7
115
DIFFERENTIAL INPUT
TERMINATION RESISTANCE (Ω)
40
35
30
25
DJ (p-p)
20
15
10
RJ (rms)
–20
0
20
40
60
80
140
FALL TIME
120
RISE TIME
100
80
60
40
06470-022
20
40
90
–20
0
20
40
60
80
100
Figure 24. Differential Input Termination Resistance vs. Temperature
160
20
95
TEMPERATURE (°C)
Figure 21. Jitter vs. Temperature
0
100
80
–40
100
TEMPERATURE (°C)
–20
105
85
06470-021
5
110
06470-024
JITTER (ps)
3.3
120
45
RISE/FALL TIME 20% TO 80% (ps)
3.1
Figure 23. Jitter vs. Input Common-Mode Voltage
50
0
–40
2.9
INPUT COMMON-MODE VOLTAGE (V)
DIFFERENTIAL INPUT SWING (V)
0
–40
06470-023
JITTER (ps)
TA = 27°C, AVCC = 3.3 V, VTTI = 3.3 V, VTTO = 3.3 V, DVCC = 3.3 V, AMUXVCC = 5 V, AVEE = 0 V, DVEE = 0 V, differential input swing =
1000 mV, TMDS outputs terminated with external 50 Ω resistors to 3.3 V, pattern = PRBS 27 − 1, data rate = 2.25 Gbps, unless otherwise noted.
60
80
100
TEMPERATURE (°C)
Figure 22. Rise and Fall Time vs. Temperature
Rev. 0 | Page 11 of 24
AD8196
THEORY OF OPERATION
VTTI
INTRODUCTION
All four high speed TMDS channels in a given link are identical;
that is, the pixel clock can be run on any of the four TMDS
channels. Transmit and receive channel compensation is provided
for the high speed channels where the user can (manually) select
among a number of fixed settings.
50Ω
IP_xx
IN_xx
06470-025
CABLE
EQ
AVEE
Figure 25. High Speed Input Simplified Schematic
OUTPUT CHANNELS
Each high speed output differential pair is terminated to the
3.3 V VTTO power supply through two single-ended 50 Ω
on-chip resistors (see Figure 26). This output termination is
user-selectable; all the output terminations can be turned on
or off by programming the TX_PTO bit of the transmitter
settings register.
VTTO
The AD8196 has I2C serial programming with two user programmable I2C slave addresses. The I2C slave address of the
AD8196 is 0b100100X. The least significant bit, represented by
X in the address, is set by tying the I2C_ADDR pin to either
3.3 V (for the value, X = 1) or to 0 V (for X = 0).
50Ω
50Ω
OPx
ONx
DISABLE
INPUT CHANNELS
IOUT
AVEE
Each high speed input differential pair terminates to the
3.3 V VTTI power supply through a pair of single-ended 50 Ω
on-chip resistors, as shown in Figure 25. The input terminations
can be optionally disconnected for approximately 100 ms following
a source switch. The user can program which of the eight high
speed input channels employs this feature by selectively programming the associated RX_PT bits in the input termination
pulse register. Additionally, all the input terminations can be
disconnected by programming the RX_TO bit in the receiver
settings register. By default, the input termination is enabled.
The input equalizer can be manually configured to provide two
different levels of high frequency boost: 6 dB or 12 dB. The user
can individually control the equalization level of the eight high
speed input channels by selectively programming the associated
RX_EQ bits in the receive equalizer register. No specific cable
length is suggested for a particular equalization setting because
cable performance varies widely between manufacturers;
however, in general, the equalization of the AD8196 can be set
to 12 dB without degrading the signal integrity, even for short
input cables. At the 12 dB setting, the AD8196 can equalize
more than 20 meters of 24 AWG cable at data rates of 2.25 Gbps.
50Ω
06470-026
The AD8196 is a pin-to-pin HDMI 1.3 receive-compliant
replacement for the AD8190. The primary function of the
AD8196 is to switch one of two (DVI or HDMI) single link
sources to one output. Each HDMI/DVI link consists of four
differential, high speed channels and four auxiliary singleended, low speed control signals. The high speed channels
include a data-word clock and three transition minimized
differential signaling (TMDS) data channels running at 10×
the data-word clock frequency for data rates up to 2.25 Gbps.
The four low speed control signals are 5 V tolerant bidirectional
lines that can carry configuration signals, HDCP encryption,
and other information, depending upon the specific application.
Figure 26. High Speed Output Simplified Schematic
The output termination resistors of the AD8196 back-terminate
the output TMDS transmission lines. These back-terminations,
as recommended in the HDMI 1.3 specification, act to absorb
reflections from impedance discontinuities on the output traces,
improving the signal integrity of the output traces and adding
flexibility to how the output traces can be routed. For example,
interlayer vias can be used to route the AD8196 TMDS outputs
on multiple layers of the PCB without severely degrading the
quality of the output signal.
The AD8196 output has a disable feature that places the outputs
in a tristate mode. This mode is enabled by programming the
HS_EN bit of the high speed device modes register. Larger wireOR’ed arrays can be constructed using the AD8196 in this mode.
The AD8196 requires output termination resistors when the
high speed outputs are enabled. Termination can be internal
and/or external. The internal terminations of the AD8196 are
enabled by programming the TX_PTO bit of the transmitter
settings register (the default upon reset). External terminations
can be provided either by on-board resistors or by the input
termination resistors of an HDMI/DVI receiver. If both the
internal terminations are enabled and external terminations are
present, set the output current level to 20 mA by programming
the TX_OCL bit of the transmitter settings register (the default
Rev. 0 | Page 12 of 24
AD8196
upon reset). If only external terminations are provided (if the
internal terminations are disabled), set the output current level
to 10 mA by programming the TX_OCL bit of the transmitter
settings register. The high speed outputs must be disabled if
there are no output termination resistors present in the system.
The output pre-emphasis can be manually configured to provide
one of four different levels of high frequency boost. The specific
boost level is selected by programming the TX_PE bits of the
transmitter settings register. No specific cable length is suggested
for a particular pre-emphasis setting because cable performance
varies widely between manufacturers.
SWITCHING MODE
The AD8196 behaves like a 2:1 HDMI/DVI link multiplexer by
routing groups of four TMDS input channels to the four channel
output. In this mode, the user selects the group of high speed
source signals (A or B) that is routed to the output by programming the HS_CH bit of the high speeds modes register as
shown in Table 7. The group of low speed auxiliary source
signals (AUX_A or AUX_B) that is routed to the common
output is separately set by programming the AUX_CH bit of
the auxiliary device register as shown in Table 9.
pins are in a high impedance state. A scenario that illustrates
this requirement is one where the auxiliary multiplexer is used
to switch the display data channel (DDC) bus. In some applications, additional devices can be connected to the DDC bus
(such as an EEPROM with EDID information) upstream of the
AD8196. Extended display identification data (EDID) is a VESA
standard-defined data format for conveying display configuration
information to sources to optimize display use. EDID devices
may need to be available via the DDC bus, regardless of the state
of the AD8196 and any downstream circuit. For this configuration, the auxiliary inputs of the powered down AD8196 need to
be in a high impedance state to avoid pulling down on the DDC
lines and preventing these other devices from using the bus.
When the AD8196 is powered from a simple resistor network,
as shown in Figure 28, it uses the 5 V supply that is required
from any HDMI/DVI source to guarantee high impedance of
the auxiliary multiplexer pins. The AMUXVCC supply does not
draw any static current; therefore, it is recommended that the
resistor network tap the 5 V supplies as close to the connectors
as possible to avoid any additional voltage drop.
This precaution does not need to be taken if the DDC peripheral
circuitry is connected to the bus downstream of the AD8196.
AUXILIARY LINES SWITCHING
The auxiliary (low speed) lines have no amplification. They are
routed using a passive switch that is bandwidth compatible with
standard speed I2C. The schematic equivalent for this passive
connection is shown in Figure 27.
10kΩ
I < 50mA
10MΩ
+5V INTERNAL
(IF ANY)
AD8196
PERIPHERAL
CIRCUITRY
PERIPHERAL
CIRCUITRY
AUX_COM0
½CAUX
I < 50mA
SOURCE B +5V
Figure 27. Auxiliary Channel Simplified Schematic
Showing AUX_A0 to AUX_COM0 Routing
10kΩ
PIN 18 HDMI CONNECTOR
PIN 14 DVI CONNECTOR
When turning off the AD8196, care needs to be taken with
the AMUXVCC supply to ensure that the auxiliary multiplexer
Rev. 0 | Page 13 of 24
Figure 28. Suggested AMUXVCC Power Scheme
06470-028
½CAUX
RAUX
SOURCE A +5V
AMUXVCC
06470-027
AUX_A0
PIN 18 HDMI CONNECTOR
PIN 14 DVI CONNECTOR
AD8196
SERIAL CONTROL INTERFACE
RESET
6.
Wait for the AD8196 to acknowledge the request.
On initial power-up, or at any point in operation, the AD8196
register set can be restored to the default values by pulling the
RESET pin to low according to the specification in Table 1.
During normal operation, however, the RESET pin must be
pulled up to 3.3 V. Pulling the RESET pin to low sets the
HS_CH register to 0 (Input A) and incurs the associated
switching delay before the input can be switched to Input B,
regardless of the previous state of the AD8196.
7.
Send the data (eight bits) to be written to the register
whose address was set in Step 5. This transfer should be
MSB first.
8.
Wait for the AD8196 to acknowledge the request.
9.
Do one of the following:
a.
Send a stop condition (while holding the I2C_SCL
line high, pull the I2C_SDA line high) and release
control of the bus to end the transaction (shown in
Figure 29).
b.
Send a repeated start condition (while holding the
I2C_SCL line high, pull the I2C_SDA line low) and
continue with Step 2 in this procedure to perform
another write.
c.
Send a repeated start condition (while holding the
I2C_SCL line high, pull the I2C_SDA line low) and
continue with Step 2 of the read procedure (in the
Read Procedure section) to perform a read from
another address.
d.
Send a repeated start condition (while holding the
I2C_SCL line high, pull the I2C_SDA line low) and
continue with Step 8 of the read procedure (in the
Read Procedure section) to perform a read from the
same address set in Step 5.
WRITE PROCEDURE
To write data to the AD8196 register set, an I2C master (such as
a microcontroller) needs to send the appropriate control signals
to the AD8196 slave device. The signals are controlled by the
I2C master, unless otherwise specified. For a diagram of the
procedure, see Figure 29. The steps for a write procedure are as
follows:
1.
Send a start condition (while holding the I2C_SCL line
high, pull the I2C_SDA line low).
2.
Send the AD8196 part address (seven bits). The upper six
bits of the AD8196 part address are the static value [100100]
and the LSB is set by Input Pin I2C_ADDR. This transfer
should be MSB first.
3.
Send the write indicator bit (0).
4.
Wait for the AD8196 to acknowledge the request.
5.
Send the register address (eight bits) to which data is to be
written. This transfer should be MSB first.
*
I2C_SCL
R/W
GENERAL CASE
I2C_SDA
START
FIXED ADDR PART
REGISTER ADDR
ADDR
ACK
DATA
STOP
ACK
ACK
EXAMPLE
I2C_SDA
2
3
4
5
*THE SWITCHING/UPDATE DELAY BEGINS AT THE FALLING EDGE OF THE
LAST DATA BIT; FOR EXAMPLE, THE FALLING EDGE JUST BEFORE STEP 8.
Figure 29. I2C Write Procedure
Rev. 0 | Page 14 of 24
6
7
8
9
06470-029
1
AD8196
I2C_SCL
R/W
GENERAL CASE
I2C_SDA
START
R/W
FIXED PART ADDR
SR
REGISTER ADDR
ADDR ACK
FIXED PART ADDR
ACK
DATA
ADDR ACK
STOP
ACK
1
2
3
4
5
6
7
8
9 10 11
12
13
06470-030
EXAMPLE
I2C_SDA
Figure 30. I2C Read Procedure
READ PROCEDURE
13. Do one of the following:
2
To read data from the AD8196 register set, an I C master (such
as a microcontroller) needs to send the appropriate control
signals to the AD8196 slave device. The signals are controlled
by the I2C master, unless otherwise specified. For a diagram of
the procedure, see Figure 30. The steps for a read procedure are
as follows:
1.
2.
a.
Send a stop condition (while holding the I2C_SCL
line high, pull the SDA line high) and release control
of the bus to end the transaction (shown in Figure 30).
b.
Send a start condition (while holding the I2C_SCL line
high, pull the I2C_SDA line low).
Send a repeated start condition (while holding the
I2C_SCL line high, pull the I2C_SDA line low) and
continue with Step 2 of the write procedure (see the
previous Write Procedure section) to perform a write.
c.
Send the AD8196 part address (seven bits). The upper six
bits of the AD8196 part address are the static value [100100]
and the LSB is set by Input Pin I2C_ADDR. This transfer
should be MSB first.
Send a repeated start condition (while holding the
I2C_SCL line high, pull the I2C_SDA line low) and
continue with Step 2 of this procedure to perform a
read from another address.
d.
Send a repeated start condition (while holding the
I2C_SCL line high, pull the I2C_SDA line low) and
continue with Step 8 of this procedure to perform a
read from the same address.
3.
Send the write indicator bit (0).
4.
Wait for the AD8196 to acknowledge the request.
5.
Send the register address (eight bits) from which data is to
be read. This transfer should be MSB first.
6.
Wait for the AD8196 to acknowledge the request.
7.
Send a repeated start condition (Sr) by holding the
I2C_SCL line high and pulling the I2C_SDA line low.
8.
Resend the AD8196 part address (seven bits) from Step 2.
The upper six bits of the AD8196 part address compose the
static value [100100]. The LSB is set by Input Pin I2C_ADDR.
This transfer should be MSB first.
9.
Send the read indicator bit (1).
10. Wait for the AD8196 to acknowledge the request.
11. The AD8196 serially transfers the data (eight bits) held in
the register indicated by the address set in Step 5. This data
is sent MSB first.
SWITCHING/UPDATE DELAY
There is a delay between when a user writes to the configuration registers of the AD8196 and when that state change takes
physical effect. This update delay begins at the falling edge of
I2C_SCL for the last data bit transferred, as shown in Figure 29.
This update delay is register specific and the times are specified
in Table 1.
During a delay window, new values can be written to the
configuration registers but the AD8196 does not physically
update until the end of that register’s delay window. Writing
new values during the delay window does not reset the window;
new values supersede the previously written values. At the end
of the delay window, the AD8196 physically assumes the state
indicated by the last set of values written to the configuration
registers. If the configuration registers are written after the delay
window ends, the AD8196 immediately updates and a new
delay window begins.
12. Acknowledge the data from the AD8196.
Rev. 0 | Page 15 of 24
AD8196
CONFIGURATION REGISTERS
The serial interface configuration registers can be read and written using the I2C serial interface, Pin I2C_SDA, and Pin I2C_SCL.
The LSB of the AD8196 I2C part address is set by tying Pin I2C_ADDR to 3.3 V (I2C_ADDR = 1) or 0 V (I2C_ADDR = 0).
Table 5. Register Map
Name
High Speed
Device
Modes
Bit 7
Bit 0
High speed
source select
HS_CH
Auxiliary
switch
source select
AUX_EN
AUX_CH
High speed
input
termination
select
RX_TO
Input termination pulse-on-source-switch select (disconnect termination for a short period of time)
Auxiliary
Device
Modes
Receiver
Settings
Input
Termination
Pulse
Receive
Equalizer
Bit 6
High speed
switch enable
HS_EN
Auxiliary
switch enable
Bit 5
Bit 4
RX_PT[7]
RX_PT[6]
RX_PT[5]
RX_EQ[7]
RX_EQ[6]
RX_EQ[5]
Bit 3
RX_PT[4]
Bit 2
RX_PT[3]
Bit 1
RX_PT[2]
RX_PT[1]
RX_PT[0]
RX_EQ[1]
High speed
output
termination
select
TX_PTO
RX_EQ[0]
High speed
output
current level
select
TX_OCL
Input equalization level select
RX_EQ[4]
Transmitter
Settings
RX_EQ[3] RX_EQ[2]
High speed output
pre-emphasis level
select
TX_PE[1]
TX_PE[0]
Addr.
0x00
Default
0x40
0x01
0x40
0x10
0x01
0x11
0x00
0x13
0x00
0x20
0x03
HIGH SPEED DEVICE MODES REGISTER
AUXILIARY DEVICE MODES REGISTER
HS_EN: High Speed (TMDS) Switch Enable Bit
AUX_EN: Auxiliary (Low Speed) Switch Enable Bit
Table 6. HS_EN Description
Table 8. AUX_EN Description
HS_EN
0
1
AUX_EN
0
Description
High speed channels off, low power/standby mode
High speed channels on
1
HS_CH: High Speed (TMDS) Source Select Bit
Description
Auxiliary switch off, no low speed input/output to
low speed common input/output connection
Auxiliary switch on
AUX_CH: Auxiliary (Low Speed) Switch Source Select Bit
Table 7. HS_CH Mapping
HS_CH
0
1
O[3:0]
A[3:0]
B[3:0]
Description
High speed Source A switched to output
High speed Source B switched to output
Table 9. AUX_CH Mapping
AUX_CH
0
AUX_COM[3:0]
AUX_A[3:0]
1
AUX_B[3:0]
Rev. 0 | Page 16 of 24
Description
Auxiliary Source A switched to
output
Auxiliary Source B switched to
output
AD8196
RECEIVER SETTINGS REGISTER
RECEIVE EQUALIZER REGISTER
RX_TO: High Speed (TMDS) Input Termination On/Off
Select Bit
RX_EQ[X]: High Speed (TMDS) Input X Equalization Level
Select Bit
Table 10. RX_TO Description
Table 13. RX_EQ[X] Description
RX_TO
0
1
RX_EQ[X]
0
1
Description
Input termination off
Input termination on (can be pulsed on and off
when source is switched, according to settings in
the input termination pulse register)
INPUT TERMINATION PULSE REGISTER
RX_PT[X]: High Speed (TMDS) Input Termination X
Pulse-On-Source Switch Select Bit
Table 11. RX_PT[X] Description
RX_PT[X]
0
1
Description
Input termination for TMDS Channel X always
connected when source is switched
Input termination for TMDS Channel X
disconnected for approximately 100 ms when
source is switched
Table 12. RX_PT[X] Mapping
RX_PT[X]
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Corresponding Input TMDS Channel
A0
A1
A2
A3
B3
B2
B1
B0
Description
Low equalization (6 dB)
High equalization (12 dB)
Table 14. RX_EQ[X] Mapping
RX_EQ[X]
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Corresponding Input TMDS Channel
A0
A1
A2
A3
B3
B2
B1
B0
TRANSMITTER SETTINGS REGISTER
TX_PE[1:0]: High Speed (TMDS) Output Pre-Emphasis
Level Select Bus (All TMDS Channels)
Table 15. TX_PE[1:0] Description
TX_PE[1:0]
00
01
10
11
Description
No pre-emphasis (0 dB)
Low pre-emphasis (2 dB)
Medium pre-emphasis (4 dB)
High pre-emphasis (6 dB)
TX_PTO: High Speed (TMDS) Output Termination On/Off
Select Bit (All Channels)
Table 16. TX_PTO Description
TX_PTO
0
1
Description
Output termination off
Output termination on
TX_OCL: High Speed (TMDS) Output Current Level Select
Bit (All Channels)
Table 17. TX_OCL Description
TX_OCL
0
1
Rev. 0 | Page 17 of 24
Description
Output current set to 10 mA
Output current set to 20 mA
AD8196
06470-031
APPLICATION NOTES
Figure 31. Evaluation Board Layout of the TMDS Traces
The AD8196 is an HDMI/DVI switch featuring equalized
TMDS inputs and pre-emphasized TMDS outputs. It is intended for use as a 2:1 switch in systems with long cable runs
on both the input and/or the output, and is fully HDMI 1.3
receive-compliant.
PINOUT
The AD8196 is designed to have an HDMI/DVI receiver pinout
at its input and a transmitter pinout at its output. This makes the
AD8196 ideal for use in AVR-type applications where a designer
routes both the inputs and the outputs directly to HDMI/DVI
connectors as shown in Figure 31. When the AD8196 is used in
receiver-type applications, it is necessary to change the order of
the output pins on the PCB to align with the on-board receiver.
One advantage of the AD8196 in an AVR-type application is
that all of the high speed signals can be routed on one side (the
topside) of the board, as shown in Figure 31. In addition to
12 dB of input equalization, the AD8196 provides up to 6 dB of
output pre-emphasis that boosts the output TMDS signals and
allows the AD8196 to precompensate when driving long PCB
traces or output cables. The net effect of the input equalization
and output pre-emphasis of the AD8196 is that the AD8196 can
compensate for the signal degradation of both input and output
cables; it acts to reopen a closed input data eye and transmit a
full swing HDMI signal to an end receiver. More information
on the specific performance metrics of the AD8196 can be
found in the Typical Performance Characteristics section.
The AD8196 also provides a distinct advantage in receive-type
applications because it is a fully buffered HDMI/DVI switch.
Although inverting the output pin order of the AD8196 on the
PCB requires a designer to place vias in the high speed signal
path, the AD8196 fully buffers and electrically decouples the
outputs from the inputs. Therefore, the effects of the vias placed
on the output signal lines are not seen at the input of the AD8196.
The programmable output terminations also improve signal
quality at the output of the AD8196. The PCB designer, therefore, has significantly improved flexibility in the placement and
routing of the output signal path with the AD8196 over other
solutions.
Rev. 0 | Page 18 of 24
AD8196
CABLE LENGTHS AND EQUALIZATION
The AD8196 offers two levels of programmable equalization
for the high speed inputs: 6 dB and 12 dB. The equalizer of
the AD8196 supports video data rates of up to 2.25 Gbps, and
as shown in Figure 14, it can equalize more than 20 meters of
24 AWG HDMI cable at 2.25 Gbps, which corresponds to the video
format, 1080p with deep color.
The length of cable that can be used in a typical HDMI/DVI
application depends on a large number of factors including
•
Cable quality: the quality of the cable in terms of conductor
wire gauge and shielding. Thicker conductors have lower
signal degradation per unit length.
•
Data rate: the data rate being sent over the cable. The signal
degradation of HDMI cables increases with data rate.
•
Edge rates: the edge rates of the source input. Slower input
edges result in more significant data eye closure at the end
of a cable.
•
Receiver sensitivity: the sensitivity of the terminating
receiver.
As such, specific cable types and lengths are not recommended
for use with a particular equalizer setting. In nearly all applications, the AD8196 equalization level can be set to high, or 12 dB,
for all input cable configurations at all data rates, without degrading
the signal integrity.
THE AD8196 AS A SINGLE-CHANNEL BUFFER
The AD8196 can be used as a single-channel TMDS buffer
without the need for any external I2C control. In its default
configuration, the AD8196 connects both the high speed and
low speed channels of Input A to their respective outputs, sets
the input equalization level to 6 dB, the output pre-emphasis
level to 0 dB, enables both the output and input terminations,
and provides a fully functioning HDMI link with TMDS
buffering.
The AD8196 enters this default state whenever the RESET pin is
pulled to low in accordance with the specification in Table 1.
PCB LAYOUT GUIDELINES
The AD8196 is used to switch two distinctly different types of
signals, both of which are required for HDMI and DVI video.
These signal groups require different treatment when laying out
a PC board.
The first group of signals carries the audiovisual (AV) data.
HDMI/DVI video signals are differential, unidirectional, and
high speed (up to 2.25 Gbps). The channels that carry the video
data over the PCB must be controlled impedance, terminated at
the receiver, and capable of operating at the maximum specified
system data rate. It is especially important to note that the differential traces that carry the TMDS signals should be designed
with a controlled differential impedance of 100 Ω. The AD8196
provides single-ended 50 Ω terminations on-chip for both its
inputs and outputs, and both the input and output terminations
can be enabled or disabled through the serial interface. Transmitter termination is not required by the HDMI 1.3 standard but
its inclusion improves the overall system signal integrity.
The audiovisual (AV) data carried on these high speed channels
is encoded by a technique called transition minimized differential signaling (TMDS) and in the case of HDMI, is also encrypted
according to the high bandwidth digital copy protection (HDCP)
standard.
The second group of signals consists of low speed auxiliary
control signals used for communication between a source and a
sink. Depending upon the application, these signals can include
the DDC bus (this is an I2C bus used to send EDID information
and HDCP encryption keys between the source and the sink),
the consumer electronics control (CEC) line, and the hot plug
detect (HPD) line. These auxiliary signals are bidirectional, low
speed, and transferred over a single-ended transmission line
that does not need to have controlled impedance. The primary
concern with laying out the auxiliary lines is ensuring that they
conform to the I2C bus standard and do not have excessive
capacitive loading.
TMDS Signals
In the HDMI/DVI standard, four differential pairs carry the
TMDS signals. In DVI, three of these pairs are dedicated to
carrying RGB video and sync data. For HDMI, audio data
interleaves with the video data; the DVI standard does not incorporate audio information. The fourth high speed differential pair
is used for the AV data-word clock, and runs at one-tenth the
speed of the TMDS data channels.
The four high speed channels of the AD8196 are identical.
No concession was made to lower the bandwidth of the fourth
channel for the pixel clock, so any channel can be used for any
TMDS signal. The user chooses which signal is routed over
which channel. Additionally, the TMDS channels are symmetrical;
therefore, the p and n of a given differential pair are interchangeable, provided the inversion is consistent across all inputs
and outputs of the AD8196. However, the routing between inputs
and outputs through the AD8196 is fixed. For example, Output
Channel 0 always switches between Input A0 and Input B0, and
so forth.
The AD8196 buffers the TMDS signals and the input traces can
be considered electrically independent of the output traces. In
most applications, the quality of the signal on the input TMDS
traces are more sensitive to the PCB layout. Regardless of the
data being carried on a specific TMDS channel, or whether the
TMDS line is at the input or the output of the AD8196, all four
high speed signals should be routed on a PCB in accordance
with the same RF layout guidelines.
Rev. 0 | Page 19 of 24
AD8196
Layout for the TMDS Signals
The TMDS differential pairs can either be microstrip traces,
routed on the outer layer of a board, or stripline traces, routed
on an internal layer of the board. If microstrip traces are used,
there should be a continuous reference plane on the PCB layer
directly below the traces. If stripline traces are used, they must
be sandwiched between two continuous reference planes in the
PCB stack-up. Additionally, the p and n of each differential pair
must have a controlled differential impedance of 100 Ω. The
characteristic impedance of a differential pair is a function of
several variables including the trace width, the distance separating
the two traces, the spacing between the traces and the reference
plane, and the dielectric constant of the PC board binder material.
Interlayer vias introduce impedance discontinuities that can
cause reflections and jitter on the signal path, therefore, it is
preferable to route the TMDS lines exclusively on one layer of the
board, particularly for the input traces. Additionally, to prevent
unwanted signal coupling and interference, route the TMDS
signals away from other signals and noise sources on the PCB.
Both traces of a given differential pair must be equal in length
to minimize intrapair skew. Maintaining the physical symmetry
of a differential pair is integral to ensuring its signal integrity;
excessive intrapair skew can introduce jitter through duty cycle
distortion (DCD). The p and n of a given differential pair should
always be routed together to establish the required 100 Ω differential impedance. Enough space should be left between the
differential pairs of a given group so that the n of one pair does
not couple to the p of another pair. For example, one technique is
to make the interpair distance 4 to 10 times wider than the
intrapair spacing.
Any one group of four TMDS channels (Input A, Input B, or the
output) should have closely matched trace lengths to minimize
interpair skew. Severe interpair skew can cause the data on the
four different channels of a group to arrive out of alignment
with one another. A good practice is to match the trace lengths
for a given group of four channels to within 0.05 inches on FR4
material.
Controlling the Characteristic Impedance of a TMDS
Differential Pair
The characteristic impedance of a differential pair depends on
a number of variables including the trace width, the distance
between the two traces, the height of the dielectric material
between the trace and the reference plane below it, and the
dielectric constant of the PCB binder material. To a lesser
extent, the characteristic impedance also depends upon the
trace thickness and the presence of solder mask. There are
many combinations that can produce the correct characteristic
impedance. Generally, working with the PC board fabricator is
required to obtain a set of parameters to produce the desired
results.
One consideration is how to guarantee a differential pair with
a differential impedance of 100 Ω over the entire length of the
trace. One technique to accomplish this is to change the width
of the traces in a differential pair based on how closely one trace
is coupled to the other. When the two traces of a differential
pair are close and strongly coupled, they should have a width
that produces a 100 Ω differential impedance. When the traces
split apart to go into a connector, for example, and are no longer
so strongly coupled, the width of the traces should be increased
to yield a differential impedance of 100 Ω in the new configuration.
Ground Current Return
In some applications, it can be necessary to invert the output
pin order of the AD8196. This requires a designer to route the
TMDS traces on multiple layers of the PCB. When routing differential pairs on multiple layers, it is necessary to also reroute
the corresponding reference plane to provide one continuous
ground current return path for the differential signals. Standard
plated through-hole vias are acceptable for both the TMDS
traces and the reference plane. An example of this is illustrated
in Figure 32.
THROUGH-HOLE VIAS
SILKSCREEN
LAYER 1: SIGNAL (MICROSTRIP)
Though the AD8196 features input equalization and output preemphasis, the length of the TMDS traces should be minimized
to reduce overall system signal degradation. Commonly used
PC board material such as FR4 is lossy at high frequencies, so
long traces on the circuit board increase signal attenuation,
resulting in decreased signal swing and increased jitter through
intersymbol interference (ISI).
PCB DIELECTRIC
LAYER 2: GND (REFERENCE PLANE)
PCB DIELECTRIC
LAYER 3: PWR
(REFERENCE PLANE)
PCB DIELECTRIC
LAYER 4: SIGNAL (MICROSTRIP)
SILKSCREEN
KEEP REFERENCE PLANE
ADJACENT TO SIGNAL ON ALL
LAYERS TO PROVIDE CONTINUOUS
GROUND CURRENT RETURN PATH.
Figure 32. Example Routing of Reference Plane
Rev. 0 | Page 20 of 24
06470-032
Minimizing intra- and interpair skew becomes increasingly
important as data rates increase. Any introduced skew constitutes a correspondingly larger fraction of a bit period at higher
data rates.
AD8196
3W
TMDS Terminations
The AD8196 provides internal 50 Ω single-ended terminations
for all of its high speed inputs and outputs. It is not necessary to
include external termination resistors for the TMDS differential
pairs on the PCB.
W
3W
SILKSCREEN
LAYER 1: SIGNAL (MICROSTRIP)
PCB DIELECTRIC
The output termination resistors of the AD8196 back-terminate
the output TMDS transmission lines. These back-terminations
act to absorb reflections from impedance discontinuities on the
output traces, improving the signal integrity of the output traces
and adding flexibility to how the output traces can be routed.
For example, interlayer vias can be used to route the AD8196
TMDS outputs on multiple layers of the PCB without severely
degrading the quality of the output signal.
LAYER 2: GND (REFERENCE PLANE)
PCB DIELECTRIC
LAYER 3: PWR (REFERENCE PLANE)
PCB DIELECTRIC
LAYER 4: SIGNAL (MICROSTRIP)
REFERENCE LAYER
RELIEVED UNDERNEATH
MICROSTRIP
Auxiliary Control Signals
There are four single-ended control signals associated with each
source or sink in an HDMI/DVI application. These are hot plug
detect (HPD), consumer electronics control (CEC), and two
display data channel (DDC) lines. The two signals on the DDC
bus are SDA and SCL (serial data and serial clock, respectively).
These four signals can be switched through the auxiliary bus of
the AD8196 and do not need to be routed with the same strict
considerations as the high speed TMDS signals.
In general, it is sufficient to route each auxiliary signal as a
single-ended trace. These signals are not sensitive to impedance
discontinuities, do not require a reference plane, and can be
routed on multiple layers of the PCB. However, it is best to
follow strict layout practices whenever possible to prevent the
PCB design from affecting the overall application. The specific
routing of the HPD, CEC, and DDC lines depends upon the
application in which the AD8196 is being used.
For example, the maximum speed of signals present on the
auxiliary lines are 100 kHz I2C data on the DDC lines, therefore,
any layout that enables 100 kHz I2C to be passed over the DDC
bus should suffice. The HDMI 1.3 specification, however, places
a strict 50 pF limit on the amount of capacitance that can be
measured on either SDA or SCL at the HDMI input connector.
This 50 pF limit includes the HDMI connector, the PCB, and
whatever capacitance is seen at the input of the AD8196, or an
equivalent receiver. There is a similar limit of 100 pF of input
capacitance for the CEC line.
The parasitic capacitance of traces on a PCB increases with
trace length. To help ensure that a design satisfies the HDMI
specification, the length of the CEC and DDC lines on the PCB
should be made as short as possible. Additionally, if there is a
reference plane in the layer adjacent to the auxiliary traces in
the PCB stackup, relieving or clearing out this reference plane
immediately under the auxiliary traces significantly decreases
the amount of parasitic trace capacitance. An example of the
board stackup is shown in Figure 33.
06470-033
SILKSCREEN
Figure 33. Example Board Stackup
HPD is a dc signal presented by a sink to a source to indicate
that the source EDID is available for reading. The placement of
this signal is not critical, but it should be routed as directly as
possible.
When the AD8196 is powered up, one set of the auxiliary inputs
is passively routed to the outputs. In this state, the AD8196 looks
like a 100 Ω resistor between the selected auxiliary inputs and
the corresponding outputs as illustrated in Figure 27. The AD8196
does not buffer the auxiliary signals, therefore, the input traces,
output traces, and the connection through the AD8196 all must
be considered when designing a PCB to meet HDMI/DVI specifications. The unselected auxiliary inputs of the AD8196 are placed
into a high impedance mode when the device is powered up. To
ensure that all of the auxiliary inputs of the AD8196 are in a high
impedance mode when the device is powered off, it is necessary to
power the AMUXVCC supply as illustrated in Figure 28.
In contrast to the auxiliary signals, the AD8196 buffers the
TMDS signals, allowing a PCB designer to layout the TMDS
inputs independently of the outputs.
Power Supplies
The AD8196 has five separate power supplies referenced to
two separate grounds. The supply/ground pairs are
•
AVCC/AVEE
•
VTTI/AVEE
•
VTTO/AVEE
•
•
DVCC/DVEE
AMUXVCC/DVEE
The AVCC/AVEE (3.3 V) and DVCC/DVEE (3.3 V) supplies
power the core of the AD8196. The VTTI/AVEE supply (3.3 V)
powers the input termination (see Figure 25). Similarly, the
VTTO/AVEE supply (3.3 V) powers the output termination
(see Figure 26). The AMUXVCC/DVEE supply (3.3 V to 5 V)
powers the auxiliary multiplexer core and determines the
Rev. 0 | Page 21 of 24
AD8196
maximum allowed voltage on the auxiliary lines. For example,
if the DDC bus is using 5 V I2C, then AMUXVCC should be
connected to +5 V relative to DVEE.
In applications where the AD8196 is powered by a single 3.3 V
supply, it is recommended to use two reference supply planes
and bypass the 3.3 V reference plane to the ground reference
plane with one 220 pF, one 1000 pF, two 0.01 μF, and one 4.7 μF
capacitors. The capacitors should via down directly to the
supply planes and be placed within a few centimeters of the
AD8196. The AMUXVCC supply does not require additional
bypassing. This scheme is illustrated in Figure 35.
In a typical application, all pins labeled AVEE or DVEE should
be connected directly to ground. All pins labeled AVCC,
DVCC, VTTI, or VTTO should be connected to 3.3 V, and
Pin AMUXVCC tied to 5 V. The supplies can also be powered
individually, but care must be taken to ensure that each stage of
the AD8196 is powered correctly.
Power Supply Bypassing
DECOUPLING
CAPACITORS
The AD8196 requires minimal supply bypassing. When
powering the supplies individually, place a 0.01 μF capacitor
between each 3.3 V supply pin (AVCC, DVCC, VTTI, and
VTTO) and ground to filter out supply noise. Generally, bypass
capacitors should be placed near the power pins and should
connect directly to the relevant supplies (without long intervening traces). For example, to improve the parasitic inductance
of the power supply decoupling capacitors, minimize the trace
length between capacitor landing pads and the vias as shown in
Figure 34.
AD8196
RECOMMENDED
AUXILIARY LINES
TMDS TRACES
06470-035
NOT RECOMMENDED
Figure 34. Recommended Pad Outline for Bypass Capacitors
06470-034
EXTRA ADDED INDUCTANCE
Figure 35. Example Placement of Power Supply Decoupling Capacitors
Around the AD8196
Rev. 0 | Page 22 of 24
AD8196
OUTLINE DIMENSIONS
8.00
BSC SQ
0.30
0.23
0.18
0.60 MAX
0.60 MAX
56
43
42
1
PIN 1
INDICATOR
PIN 1
INDICATOR
0.50
0.40
0.30
1.00
0.85
0.80
12° MAX
SEATING
PLANE
14
29
28
15
0.30 MIN
6.50
REF
0.80 MAX
0.65 TYP
0.50 BSC
4.95
4.80 SQ
4.65
*EXPOSED
PAD
(BOTTOM VIEW)
7.75
BSC SQ
0.05 MAX
0.02 NOM
COPLANARITY
0.08
0.20 REF
COMPLIANT TO JEDEC STANDARDS MO-220-VLLD-2
*NOTE:
THE AD8196 HAS A CONDUCTIVE HEAT SLUG TO HELP DISSIPATE HEAT AND ENSURE RELIABLE OPERATION OF
THE DEVICE OVER THE FULL HDMI/DVI TEMPERATURE RANGE. THE SLUG IS EXPOSED ON THE BOTTOM OF
THE PACKAGE AND ELECTRICALLY CONNECTED TO AVEE. IT IS RECOMMENDED THAT NO PCB SIGNAL
TRACES OR VIAS BE LOCATED UNDER THE PACKAGE THAT COULD COME IN CONTACT WITH THE CONDUCTIVE
SLUG. ATTACHING THE SLUG TO AN AVEE PLANE REDUCES THE JUNCTION TEMPERATURE OF THE
DEVICE WHICH MAY BE BENEFICIAL IN HIGH TEMPERATURE ENVIRONMENTS.
011907-A
TOP
VIEW
Figure 36. 56-Lead Lead Frame Chip Scale Package [LFCSP_VQ]
8 mm × 8 mm Body, Very Thin Quad
(CP-56-3)
Dimensions shown in millimeters
ORDERING GUIDE
Model
AD8196ACPZ 1
AD8196ACPZ-R71
AD8196ACPZ-RL1
AD8196-EVAL
1
Temperature
Range
−40°C to +85°C
−40°C to +85°C
−40°C to +85°C
Package Description
56-Lead Lead Frame Chip Scale Package [LFCSP_VQ]
56-Lead Lead Frame Chip Scale Package [LFCSP_VQ], Reel
56-Lead Lead Frame Chip Scale Package [LFCSP_VQ], Reel
Evaluation Board
Z = Pb-free part.
Rev. 0 | Page 23 of 24
Package
Option
CP-56-3
CP-56-3
CP-56-3
Ordering
Quantity
750
2500
AD8196
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.
©2007 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D06470-0-1/07(0)
Rev. 0 | Page 24 of 24
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