2:1 HDMI/DVI Switch with
FEATURES
2 inputs, 1 output HDMI/DVI links
HDMI 1.3a receive and transmit compliant
±7 kV HBM ESD on HDMI input pins
4 TMDS channels per link
Supports 250 Mbps to 2.25 Gbps data rates and beyond
Supports 25 MHz to 225 MHz pixel clocks and beyond
Fully buffered unidirectional inputs/outputs
Switchable 50 Ω on-chip input terminations with
programmable or automatic control on channel switch
Equalized inputs and pre-emphasized outputs
Low added jitter
Output disable feature for reduced power dissipation
Switched output termination for building of larger arrays
Bidirectional and cascadable DDC buffers (SDA/SCL)
DDC bus logic level translation (3.3 V, 5 V)
Bidirectional and cascadable CEC buffer with integrated
pull-up resistors (27 kΩ)
Hot plug detect pulse low on channel switch
Standards compatible: DVI, HDMI 1.3a, HDCP, I
2
Serial (I
C slave) control interface
56-lead, 8 mm × 8 mm LFCSP, RoHS-compliant package
APPLICATIONS
Front panel buffer for advanced television (HDTV) sets
Standalone HDMI switcher
Multiple input displays
Projectors
A/V receivers
Set-top boxes
2
C
Equalization and DDC/CEC Buffers
AD8192
FUNCTIONAL BLOCK DIAGRAM
RESET
I2C_SDA
I2C_SCL
I2C_ADDR
VTTI
IP_A[3:0]
IN_A[3:0]
IP_B[3:0]
IN_B[3:0]
VTTI
DDC_A[1:0]
DDC_B[1:0]
HPD_A
HPD_B
SET-TOP BOX
SERIAL INTERFACE
CONFIG
INTERFACE
+
–
+
–
4
4
4
4
2
2
LOW SPEED
DVEE
CONTROL
LOGIC
SWITCH
CORE
EQ
HIGH SPEED BUFFERED
SWITCH
CORE
BIDIRECT IONAL
Figure 1.
TYPICAL APPLICATION
HDMI
RECEIVER
AD8192
Figure 2. Typical Application for HDTV Sets
BUFFERED
HDTV SET
AD8192
PE
+
4
–
4
2
DVD PLAYER
AVCC
DVCC
AMUXVCC
AVEE
DVEE
VREF_AB
VREF_COM
VTTO
OP[3:0]
ON[3:0]
DDC_COM[1:0]
CEC_O/ICEC_I/O
07050–001
07050-002
GENERAL DESCRIPTION
The AD8192 is a complete HDMI™/DVI link switch featuring
equalized TMDS inputs and pre-emphasized TMDS outputs
ideal for systems with long cable runs. The TMDS outputs can
be set to a high impedance state to reduce the power dissipation
and/or allow the construction of larger arrays using the wireOR technique. The AD8192 includes bidirectional buffering for
the DDC bus and CEC line, with integrated pull-up resistors for
the CEC line. The AD8192 is available in a space-saving, 56-lead
LFCSP surface-mount, lead-free plastic package 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 Anal og Devices for its use, nor for any infringements of p atents or other
rights of third parties that may result from its use. Specifications subject to chan ge 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.
PRODUCT HIGHLIGHTS
1. Fully HDMI 1.3a transmit and receive compliant.
2. Supports data rates up to 2.25 Gbps, enabling greater than
1080p HDMI formats with deep color (12-bit) and UXGA
(1600 × 1200) DVI resolutions.
3. Input cable equalizer enables use of long cables; more than
20 m (24 AWG) at data rates up to 2.25 Gbps.
4. Auxiliary switch isolates and buffers the DDC bus and the
CEC line, improving total system capacitance limit.
5. Hot plug detect (HPD) signal is pulsed low on link switch.
6. Manually or automatically switched input terminations.
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 ©2008 Analog Devices, Inc. All rights reserved.
AD8192
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Functional Block Diagram .............................................................. 1
Typical Application ........................................................................... 1
General Description ......................................................................... 1
Product Highlights ........................................................................... 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
Absolute Maximum Ratings ............................................................ 5
Thermal Resistance ...................................................................... 5
ESD Caution .................................................................................. 5
Pin Configuration and Function Descriptions ............................. 6
Typical Performance Characteristics ............................................. 8
Theory of Operation ...................................................................... 12
Input Channels ............................................................................ 12
Output Channels ........................................................................ 12
Switching Mode .......................................................................... 13
Pre-Emphasis .............................................................................. 13
Auxiliary Multiplexer ................................................................. 14
DDC Logic Levels ....................................................................... 14
Input/Output Mapping Control ............................................... 14
Serial Control Interface .................................................................. 15
Reset ............................................................................................. 15
Write Procedure .......................................................................... 15
Read Procedure ........................................................................... 16
Configuration Registers ................................................................. 17
High Speed Device Modes Register ......................................... 18
Auxiliary Device Modes Register ............................................. 18
Receiver Settings Register ......................................................... 18
Input Termination Control Register ........................................ 18
Receive Equalizer Register ........................................................ 18
Transmitter Settings Register .................................................... 19
Source Sign Control Register .................................................... 19
Source A Input/Output Mapping Register .............................. 19
Source B Input/Output Mapping Register .............................. 19
Applications Information .............................................................. 20
Pinout ........................................................................................... 20
Cable Lengths and Equalization ............................................... 21
TMDS Output Rise/Fall Times ................................................. 21
Front Panel Buffer for Advanced TV ....................................... 21
HDMI Switcher .......................................................................... 21
Cascading Multiple Devices ...................................................... 21
PCB Layout Guidelines .............................................................. 22
Outline Dimensions ....................................................................... 25
Ordering Guide .......................................................................... 25
REVISION HISTORY
5/08—Revision 0: Initial Version
Rev. 0 | Page 2 of 28
AD8192
SPECIFICATIONS
TA = 27°C, AVCC = 3.3 V, VTTI = 3.3 V, VTTO = 3.3 V, DVCC = 3.3 V, AMUXVCC = 5 V, VREF_AB = 5 V, VREF_COM = 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. TMDS Performance Specifications
Parameter Conditions/Comments Min Typ Max Unit
TMDS DYNAMIC PERFORMANCE
Maximum Data Rate (DR) per
Channel
Bit Error Rate (BER) PRBS 223 − 1 10−9
Added Data Jitter
Added Clock Jitter 1 ps (rms)
Differential Intrapair Skew At output 1 ps
Differential Interpair Skew At output 30 ps
TMDS EQUALIZATION PERFORMANCE
Receiver (Highest Setting)
Transmitter (Highest Setting)
1
2
TMDS INPUT CHARACTERISTICS
Input Voltage Swing Differential 150 1200 mV
Input Common-Mode Voltage (V
TMDS OUTPUT CHARACTERISTICS
High Voltage Level Single-ended high speed channel AVCC − 200 AVCC + 10 mV
Low Voltage Level Single-ended high speed channel AVCC − 600 AVCC − 400 mV
Rise/Fall Time (20% to 80%)
3
TMDS TERMINATION
Input Termination Resistance Single-ended 50 Ω
Output Termination Resistance Single-ended 50 Ω
1
Output meets transmitter eye diagram as defined in the DVI Standard Revision 1.0 and HDMI Standard Revision 1.3a.
2
Cable output meets receiver eye diagram mask as defined in the DVI Standard Revision 1.0 and HDMI Standard Revision 1.3a.
3
Output rise/fall time measurement excludes external components such as HDMI connector or external ESD protection diodes. See Applications Information section for
more information.
NRZ 2.25 Gbps
DR ≤ 2.25 Gbps, PRBS 2
7
− 1, no equalization
23 ps (p-p)
Boost frequency = 1.125 GHz 12 dB
Boost frequency = 1.125 GHz 6 dB
) AVCC − 800 AVCC mV
ICM
DR = 2.25 Gbps 50 90 150 ps
Table 2. Auxiliary Channel Performance Specifications
Parameter Symbol Conditions/Comments Min Typ Max Unit
DDC CHANNELS
Input Capacitance C
DC bias = 2.5 V, ac voltage = 3.5 V p-p, f = 100 kHz 10 15 pF
AUX
Input Low Voltage VIL 0.5 V
Input High Voltage VIH 0.7 × VREF1 V
Output Low Voltage VOL I
Output High Voltage VOH VREF
= 5 mA 0.4 V
OL
1
V
Rise Time 10% to 90%, no capacitive load 140 ns
Fall Time 90% to 10%, C
= 400 pF 100 200 ns
LOAD
Leakage 10 μA
CEC CHANNEL
Input Capacitance C
DC bias = 1.65 V, ac voltage = 2.5 V p-p, f = 100 kHz 5 25 pF
AUX
Input Low Voltage VIL 0.8 V
Input High Voltage VIH 2.0 V
Output Low Voltage VOL R
= 3 kΩ to +3.3 V 0.6 V
PULLUP
Output High Voltage, VOH 2.5 AVCC V
Rev. 0 | Page 3 of 28
AD8192
Parameter Symbol Conditions/Comments Min Typ Max Unit
Rise Time
10% to 90%, C
7200 pF, R
Fall Time
90% to 10%, C
7200 pF, R
Leakage
Off-leakage test conditions from HDMI Compliance Test
PULLUP
PULLUP
= 1500 pF, R
LOAD
= 3 kΩ
= 1500 pF, R
LOAD
= 3 kΩ
= 27 kΩ; or C
PULLUP
= 27 kΩ; or C
PULLUP
LOAD
LOAD
=
=
Specification Test ID: 8-14
HOT PLUG DETECT
Output Low Voltage VOL R
1
VREF refers to the voltage at the VREF_AB or VREF_COM pins. VREF should be at the same supply voltage as that to which the external pull-up resistors are connected.
= 800 Ω to +5 V 0.4 V
PULLUP
Table 3. Power Supply and Control Logic Specifications
Parameter Conditions/Comments Min Typ Max Unit
POWER SUPPLY
AVCC Operating range (3.3 V ± 5%) 3.135 3.3 3.465 V
AMUXVCC Operating range (5 V ± 10%) 4.5 5 5.5 V
VREF_AB 3 5 5.5 V
VREF_COM 3 5 5.5 V
QUIESCENT CURRENT
AVCC Outputs disabled 40 45 mA
AVCC Outputs enabled, no pre-emphasis 60 70 mA
AVCC Outputs enabled, maximum pre-emphasis 100 120 mA
VTTI Input termination on
1
40 54 mA
VTTO Outputs enabled, output termination on 40 50 mA
Output termination on, maximum pre-emphasis 80 100 mA
DVCC 10 15 mA
VREF_AB 1 10 μA
VREF_COM 1 10 μA
AMUXVCC 10 20 mA
POWER DISSIPATION
Outputs disabled 215 318 mW
Outputs enabled, no pre-emphasis 545 765 mW
Outputs enabled, maximum pre-emphasis 881 1200 mW
I2C® AND LOGIC INPUTS
2
Input High Voltage, VIH Serial interface 2.4 V
Input Low Voltage, VIL Serial interface 0.8 V
I2C AND LOGIC OUTPUTS
Output Low Voltage, VOL Serial interface, IOL = +3 mA 0.4 V
1
Assumes that the unselected HDMI/DVI link is deactivated through the hot plug detect line, as required by the DVI Standard Revision 1.0 and HDMI Standard Revision 1.3a.
2
The AD8192 is an I2C slave and its control interface is based on the 3.3 V I2C bus specification.
50 100 μs
5 10 μs
1.8 μA
Rev. 0 | Page 4 of 28
AD8192
ABSOLUTE MAXIMUM RATINGS
Table 4.
Parameter Rating
AVCC to AVEE 3.7 V
DVCC to DVEE 3.7 V
DVEE to AVEE ±0.3 V
VTTI AVCC + 0.6 V
VTTO AVCC + 0.6 V
AMUXVCC 5.5 V
VREF_AB 5.5 V
VREF_COM 5.5 V
Internal Power Dissipation 2.41 W
High Speed Input Voltage AVCC − 1.4 V < VIN < AVCC + 0.6 V
High Speed Differential
Input Voltage
Low Speed Input Voltage DVEE − 0.3 V < VIN < AMUXVCC + 0.6 V
I2C Logic Input Voltage DVEE − 0.3 V < VIN < DVCC + 0.6 V
Storage Temperature
Range
Operating Temperature
Range
Junction Temperature 150°C
ESD HBM Input Pins Only ±7 kV
ESD HBM All Other Pins ±1.5 kV
2.0 V
−65°C to +125°C
−40°C to +85°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.
THERMAL RESISTANCE
θJA is specified for the worst-case conditions, that is, a device
soldered in a four-layer JEDEC circuit board for surface-mount
packages. θ
is specified for the exposed pad soldered to the
JC
circuit board with no airflow.
Table 5. Thermal Resistance
Model θJA θJC Unit
56-Lead LFCSP 27 2.1 °C/W
ESD CAUTION
Rev. 0 | Page 5 of 28
AD8192
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
PD_A
DDC_COM051VREF_AB52DVEE53CEC_I/O54H
50
AD8192
TOP VIEW
(Not to Scale)
1
DDC_B046CEC_O/I47AMUXVCC48VREF_COM49DDC_COM
DDC_B143HPD_B
44
45
42
41
40
39
38
37
36
35
34
33
32
31
30
29
AVCC
IN_A0
IP_A0
AVEE
IN_A1
IP_A1
VTTI
IN_A2
IP_A2
AVCC
IN_A3
IP_A3
AVEE
I2C_ADDR
0
DDC_A156DDC_A
55
PIN 1
1
INDICATO R
2
3
4
5
6
7
8
9
10
11
12
13
14
AVCC
IP_B3
IN_B3
AVEE
IP_B2
IN_B2
VTTI
IP_B1
IN_B1
AVCC
IP_B0
IN_B0
AVEE
I2C_SDA
16
15
ON0
DVCC
NOTES
1. THE AD8192 LFCSP HAS AN EXPOSED PADDLE (ePAD) ON THE UNDERSIDE
OF THE PACKAGE WHICH AIDS IN HEAT DISSIPATION. THE ePAD MUST BE
ELECTRICAL LY CONNECTED TO THE AVEE SUPPLY PLANE IN ORDER TO
MEET THERMAL SPECIFICATIONS.
21
17
19
20
22
23
24
25
26
27
18
OP0
OP1
ON1
ON2
VTTO
DVCC
28
OP2
OP3
SCL
ON3
_
VTTO
C
RESET
I2
07050-003
Figure 3. Pin Configuration
Table 6. Pin Function Descriptions
Pin No. Mnemonic Type
1
Description
1, 10, 33, 42 AVCC Power Positive Analog Supply. 3.3 V nominal.
2 IN_A0 HS I/O High Speed Input Complement.
3 IP_A0 HS I/O High Speed Input.
4, 13, 30, 39, ePAD AVEE Power Negative Analog Supply. 0 V nominal.
5 IN_A1 HS I/O High Speed Input Complement.
6 IP_A1 HS I/O High Speed Input.
7, 36 VTTI Power Input Termination Supply. Nominally connected to AVCC.
8 IN_A2 HS I/O High Speed Input Complement.
9 IP_A2 HS I/O High Speed Input.
11 IN_A3 HS I/O High Speed Input Complement.
12 IP_A3 HS I/O High Speed Input.
14 I2C_ADDR Control I2C Address LSB.
15, 21 DVCC Power Positive Digital Power Supply. 3.3 V nominal.
16 ON0 HS I/O High Speed Output Complement.
17 OP0 HS I/O High Speed Output.
18, 24 VTTO Power Output Termination Supply. Nominally connected to AVCC.
19 ON1 HS I/O High Speed Output Complement.
20 OP1 HS I/O High Speed Output.
22 ON2 HS I/O High Speed Output Complement.
23 OP2 HS I/O High Speed Output.
25 ON3 HS I/O High Speed Output Complement.
26 OP3 HS I/O High Speed Output.
27
RESET
Control Configuration Registers Reset. Normally pulled to AVCC.
28 I2C_SCL Control I2C Clock.
29 I2C_SDA Control I2C Data.
31 IN_B0 HS I/O High Speed Input Complement.
32 IP_B0 HS I/O High Speed Input.
34 IN_B1 HS I/O High Speed Input Complement.
35 IP_B1 HS I/O High Speed Input.
Rev. 0 | Page 6 of 28
AD8192
Pin No. Mnemonic Type
1
Description
37 IN_B2 HS I/O High Speed Input Complement.
38 IP_B2 HS I/O High Speed Input.
40 IN_B3 HS I/O High Speed Input Complement.
41 IP_B3 HS I/O High Speed Input.
43 HPD_B LS O Hot Plug Detect Output.
44 DDC_B1 LS I/O Display Data Channel Input/Output.
45 DDC_B0 LS I/O Display Data Channel Input/Output.
46 CEC_O/I LS I/O Consumer Electronics Control Output/Input.
47 AMUXVCC Power Positive Auxiliary Switch Supply. 5 V typical.
48 VREF_COM Reference Positive Auxiliary Switch Supply Common Side.
49 DDC_COM1 LS I/O Display Data Channel Common Input/Output.
50 DDC_COM0 LS I/O Display Data Channel Common Input/Output.
51 VREF_AB Reference Positive Auxiliary Switch Supply Source Side.
52 DVEE Power Negative Digital and Auxiliary Switch Power Supply. 0 V nominal.
53 CEC_I/O LS I/O Consumer Electronics Control Input/Output.
54 HPD_A LS O Hot Plug Detect Output.
55 DDC_A1 LS I/O Display Data Channel Input/Output.
56 DDC_A0 LS I/O Display Data Channel Input/Output.
1
HS = high speed, LS = low speed, I = input, O = output.
Rev. 0 | Page 7 of 28
AD8192
V
V
V
V
TYPICAL PERFORMANCE CHARACTERISTICS
TA = 27°C, AVCC = 3.3 V, VTTI = 3.3 V, VTTO = 3.3 V, AVEE = 0 V, DVEE = 0 V, differential input swing = 1000 mV, pattern = PRBS 27 − 1,
data rate = 2.25 Gbps, TMDS outputs terminated with external 50 Ω resistors to 3.3 V, unless otherwise noted.
HDMI CABLE
DIGITAL
PATTERN
GENERATOR
AD8192
EVALUATIO N
BOARD
SMA COAX CABLE
SERIAL DATA
ANALYZER
REFERENCE EYE DI AGRAM AT TP1
250mV/DI
0.125UI/DI V AT 2.25Gbps
Figure 5. Rx Eye Diagram at TP2 (Cable = 2 m, 30 AWG)
TP1 TP2 TP3
Figure 4. Test Circuit Diagram for Rx Eye Diagrams
250mV/DI
07050-005
Figure 7. Rx Eye Diagram at TP3, EQ = 12 dB (Cable = 2 m, 30 AWG)
0.125UI/DI V AT 2.25Gbps
07050-004
07050-007
250mV/DI
0.125UI/DI V AT 2.25Gbps
Figure 6. Rx Eye Diagram at TP2 (Cable = 20 m, 24 AWG)
07050-006
250mV/DI
0.125UI/DI V AT 2.25Gbps
07050-008
Figure 8. Rx Eye Diagram at TP3, EQ = 12 dB (Cable = 20 m, 24 AWG)
Rev. 0 | Page 8 of 28
AD8192
V
V
V
V
TA = 27°C, AVCC = 3.3 V, VTTI = 3.3 V, VTTO = 3.3 V, AVEE = 0 V, DVEE = 0 V, differential input swing = 1000 mV, pattern = PRBS 27 − 1,
data rate = 2.25 Gbps, TMDS outputs terminated with external 50 Ω resistors to 3.3 V, unless otherwise noted.
HDMI CABLE
REFERENCE EYE DI AGRAM AT TP1
250mV/DI
0.125UI/DI V AT 2.25Gbps
Figure 10. Tx Eye Diagram at TP2, PE = 0 dB
DIGITAL
PATTERN
GENERATOR
SMA COAX CABLE
AD8192
EVALUATION
BOARD
TP1 TP2 TP3
Figure 9. Test Circuit Diagram for Tx Eye Diagrams
250mV/DI
07050-010
Figure 12. Tx Eye Diagram at TP3, PE = 0 dB (Cable = 2 m, 24 AWG)
SERIAL DATA
ANALYZER
0.125UI/DI V AT 2.25Gbps
07050-009
07050-012
250mV/DI
0.125UI/DI V AT 2.25Gbps
Figure 11. Tx Eye Diagram at TP2, PE = 6 dB
07050-011
250mV/DI
0.125UI/DI V AT 2.25Gbps
Figure 13. Tx Eye Diagram at TP3, PE = 6 dB (Cable = 10 m, 24 AWG)
07050-013
Rev. 0 | Page 9 of 28
AD8192
TA = 27°C, AVCC = 3.3 V, VTTI = 3.3 V, VTTO = 3.3 V, AVEE = 0 V, DVEE = 0 V, differential input swing = 1000 mV, pattern = PRBS 27 − 1,
data rate = 2.25 Gbps, TMDS outputs terminated with external 50 Ω resistors to 3.3 V, unless otherwise noted.
0.6
0.5
0.4
0.3
2.25Gbp s,
EQ = 12dB
0.2
DETERMINISTIC JITTER (UI)
0.1
0
0 5 10 15 35
1.5Gbp s,
EQ = 12dB
ALL CABLES = 24 AWG
CABLE LENGTH (m)
20 25 30
0.75Gbp s,
EQ = 12dB
Figure 14. Jitter vs. Input Cable Length (See Figure 4 for Test Setup)
50
45
40
35
30
25
JITTER ( ps)
20
15
10
5
0
0 0.2 0.6 1.0 2.4
DATA RATE (Gb ps)
DJ, EQ = 12dB
RJ, EQ = 12dB
1.4 1.8 2.20.4 0. 8 1.2 1.6 2.0
Figure 15. Jitter vs. Data Rate
0.6
ALL CABLES = 24 AWG, EQ = 12dB
0.5
0.4
2.25Gbps, PE OFF
0.3
1.5Gbp s, PE OF F
0.2
DETERMINISTIC JITTER (UI)
0.1
07050-014
0
010
HDMI CABLE LENG TH (m)
0.75Gbp s, PE OF F
2.25Gbp s, MAX PE
1.5Gbps, MAX PE
0.75Gbp s, MAX PE
20 30
07050-017
Figure 17. Jitter vs. Output Cable Length (See Figure 9 for Test Setup)
1.2
1.0
0.8
0.6
EYE HEIGHT (V)
0.4
0.2
07050-015
0
0 0.2 0.6 1.0 2.4
DATA RATE (Gb ps)
1.4 1.8 2.20.4 0. 8 1.2 1.6 2.0
07050-018
Figure 18. Eye Height vs. Data Rate
50
DJ, EQ = 12dB
40
30
20
JITTER (ps)
10
0
3.135 3.185 3.235 3.285 3. 335 3.385 3.435
SUPPLY VOLTAGE (V)
RJ, EQ = 12dB
Figure 16. Jitter vs. Supply Voltage
07050-016
Rev. 0 | Page 10 of 28
1.2
1.0
0.8
0.6
EYE HEIGHT (V)
0.4
0.2
0
3.135 3.185 3.235 3.285 3. 335 3.385 3.435
SUPPLY VOLTAGE (V)
Figure 19. Eye Height vs. Supply Voltage
07050-019
AD8192
TA = 27°C, AVCC = 3.3 V, VTTI = 3.3 V, VTTO = 3.3 V, AVEE = 0 V, DVEE = 0 V, differential input swing = 1000 mV, pattern = PRBS 27 − 1,
data rate = 2.25 Gbps, TMDS outputs terminated with external 50 Ω resistors to 3.3 V, unless otherwise noted.
50
DJ, EQ = 12dB
40
30
20
JITTER ( ps)
10
0
0
0.5
DIFFERENTIAL SWING (V)
RJ, EQ = 12dB
1.51.0 2.0
Figure 20. Jitter vs. Differential Input Swing
50
DJ, EQ = 12dB
40
30
20
JITTER ( ps)
10
0
–40 –20 0 20 40 60 80
TEMPERATURE ( °C)
RJ, EQ = 12dB
Figure 21. Jitter vs. Temperature
50
45
40
35
30
25
JITTER (ps)
20
15
10
5
07050-020
0
2.5 3.7
2.7 2. 9 3.1 3.3 3.5
INPUT COMMON-MODE VOLTAGE (V)
DJ, EQ = 12dB
RJ, EQ = 12dB
07050-023
Figure 23. Jitter vs. Input Common-Mode Voltage
100
90
80
70
60
50
40
RESISTANCE (Ω)
30
20
10
07050-021
0
–40 –20 0 20
OUTPUT
INPUT
TEMPERATURE ( °C)
40 60 80
07050-024
Figure 24. Single-Ended Termination Resistance vs. Temperature
120
100
80
60
40
RISE/F ALL TI ME 20% TO 80% (ps)
20
0
–40 –20 0 20 40 60 80
TEMPERATURE ( °C)
Figure 22. Rise and Fall Time vs. Temperature
RISE
FALL
07050-022
Rev. 0 | Page 11 of 28
AD8192
V
V
THEORY OF OPERATION
The primary function of the AD8192 is to switch one of two
(HDMI or DVI) single link sources to one output. Each
HDMI/DVI link consists of four differential, high speed
channels and four auxiliary single-ended, 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 low speed control signals
include the display data channel (DDC) bus (SDA and SCL),
the consumer electronics control (CEC) line, and the hot plug
detect (HPD) signal.
All four high speed TMDS channels 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.
The AD8192 isolates and buffers the DDC bus. It additionally
isolates and buffers the CEC line and includes integrated pullups for the CEC line. The AD8192 also pulses the HPD signal
low upon channel switching.
The AD8192 has I
grammable I
AD8192 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).
INPUT CHANNELS
Each high speed input differential pair terminates to the 3.3 V
VTTI power supply through a pair of single-ended 50 Ω onchip resistors, as shown in Figure 25. The state of the input
terminations can be configured automatically or programmed
manually through the serial control interface. The termination
state is placed in the automatic mode by programming 0 in the
RX_TO bit of the receiver settings register. In the automatic
mode, the selected input has all terminations enabled, and the
deselected input has all input terminations disabled. This state
is automatically updated upon channel switching. In the manual
mode, 1 is programmed into the RX_TO bit of the receiver
settings register, and the state of each individual input termination is set by programming the associated RX_PT bits in the
input termination control register.
The input equalizer can be manually configured to provide two
different levels of high frequency boost: 6 dB or 12 dB. The
equalizer level defaults to 12 dB after reset. The user can
individually program the equalization level of the eight high
speed input channels by selectively setting 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 among manufacturers; however, in
general, the equalization of the AD8192 can be set to 12 dB
without degrading the signal integrity, even for short input cables.
2
C serial programming with two user pro-
2
C slave addresses. The I2C slave address of the
Rev. 0 | Page 12 of 28
TTI
50Ω50Ω
IP
IN
AVEE
Figure 25. High Speed Input Simplified Schematic
CABLE
EQ
07050-025
OUTPUT CHANNELS
Each high speed output differential pair is terminated to the
+3.3 V VTTO power supply through a pair of 50 Ω on-chip
resistors, as shown in Figure 26. This termination is userselectable; it can be turned on or off by programming the
TX_PTO bit of the transmitter settings register.
TTO
50Ω50Ω
OP ON
DISABLE
Figure 26. High Speed Output Simplified Schematic
AVEE
I
OUT
The output termination resistors of the AD8192 back terminate
the output TMDS transmission lines. These back terminations,
as recommended in the HDMI 1.3a 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 AD8192 TMDS outputs
on multiple layers of the PCB without severely degrading the
quality of the output signal.
The output has a disable feature that places the outputs in
tristate mode (HS_EN bit of the high speed device modes
register). Bigger wire-OR’ed arrays can be constructed using
the AD8192 in this mode.
The AD8192 requires output termination resistors when the
high speed outputs are enabled. Termination can be internal
and/or external. The internal terminations of the AD8192 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
upon reset). If only external terminations are provided (if the
internal terminations are disabled), set the output current level
ESD
PROT.
07050-026
AD8192
I
I
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 equalizer (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 among manufacturers.
SWITCHING MODE
The AD8192 is a 2:1 HDMI/DVI source switch. The user can
select which high speed TMDS input is routed to the output by
programming the HS_CH bit of the high speed modes register and
which low speed DDC input/output is routed to the DDC common
input/output by programming the AUX_CH bit of the auxiliary
device register.
PRE-EMPHASIS
The pre-emphasized TMDS outputs precompensate the transmitted signal to account for losses in systems with long cable
runs. These long cable runs selectively attenuate the high frequency
energy of the signal, leading to degraded transition times and
eye closure. Similar to a receive equalizer, the goal of the preemphasis filter is to boost the high frequency energy in the signal.
However, unlike the receive equalizer, the pre-emphasis filter is
applied before the channel, thus predistorting the transmitted
signal to account for the loss of the channel. The series connection
of the pre-emphasis filter and the channel results in a flatter
frequency response than that of the channel, thereby leading to
improved high frequency energy, improved transition times,
and improved eye opening on the far end of the channel. Using
a pre-emphasis filter for compensating channel losses allows for
longer cable runs with or without a receive equalizer on the far
end of the channel. When there is no receive equalizer on the
far end of the channel, the pre-emphasis filter should allow
longer cable runs than is acceptable with no pre-emphasis. In
the case of both a pre-emphasis filter on the near end and a
receive equalizer on the far end of the channel, the allowable
cable run should be longer than either compensation could
achieve alone. The pulse response of a pre-emphasized waveform is shown in Figure 27. The output voltage levels and
symbol descriptions are listed in Tabl e 7 and Tab l e 8 , respectively.
PRE-EMPHASIS OFF
V
TTO
V
OCM
PRE-EMPHASIS ON
V
TTO
V
OCM
V
OSE-DC
V
OSE-DC
<T
BIT
Figure 27. Pre-Emphasis Pulse Response
V
OSE-BOOST
V
H
V
L
V
H
V
L
07050-027
Table 7. Output Voltage Levels
PE Setting OCL Setting Boost (dB) IT (mA) V
(mV p-p) V
OSE-DC
OSE-BOOST
(mV p-p) V
OCM
DC-Coupled
(V) VH (V) VL (V)
0 0 0 10 250 250 3.175 3.3 3.050
1 0 2 12.5 250 312.5 3.144 3.3 2.988
2 0 4 15 250 375 3.133 3.3 2.925
3 0 6 20 250 500 3.050 3.3 2.8
0 1 0 20 500 500 3.050 3.3 2.8
1 1 2 25 500 625 2.988 3.3 2.675
2 1 4 30 500 750 2.925 3.3 2.550
3 1 6 40 500 1000 2.8 3.3 2.3
Table 8. Symbol Definitions
Symbol Formula Definition
V
OSE-DC
V
OSE-BOOST
V
(DC-Coupled)
OCM
V
(AC-Coupled)
OCM
V
H
V
L
1
The 25 Ω resistance in the equation is the parallel combination of the on-chip 50 Ω termination resistor and the external 50 Ω termination resistor.
I
T
=PE
IT × 25 Ω
VTTO
VTTO
V
+ V
OCM
V
− V
OCM
1
250×
1
T
T
OSE-BOOST
OSE-BOOST
252×−
/2
/2
1
502×−
Single-ended output voltage swing after settling
Boosted single-ended output voltage swing
Common-mode voltage when the output is dc-coupled
Common-mode voltage when the output is ac-coupled
High single-ended output voltage excursion
Low single-ended output voltage excursion
Rev. 0 | Page 13 of 28
AD8192
AUXILIARY MULTIPLEXER
The auxiliary (low speed) lines provide switching and buffering
for the DDC bus and buffering for the CEC line. The DDC
buffers are bidirectional and fully support arbitration, clock
synchronization, and other relevant features of a standard mode
2
C bus. The CEC buffer is bidirectional and includes integrated
I
on-chip pull-up resistors.
The HPD lines going into the AD8192 are normally high
impedance but are pulled low for greater than 100 ms when
a channel switch occurs.
The user has the option of slaving the auxiliary line switch
select to the high speed switch select by programming the
AUX_LK bit of the auxiliary device register. This causes the
auxiliary input channel to switch automatically when the user
programs the HS_CH bit of the high speed modes register.
The unselected auxiliary inputs of the AD8192 are placed into a
high impedance mode when the device is powered up and the
DDC inputs of the AD8192 are high impedance when the
device is powered off. This prevents contention on the DDC bus,
enabling a design to include an EDID upstream of the AD8192.
INPUT/OUTPUT MAPPING CONTROL
The input/output mapping of the AD8192 is completely
programmable. This allows a designer to integrate the AD8192
into virtually any application without requiring the use of vias
on the TMDS traces in the PCB layout.
The user can independently control the input/output mapping
of the TMDS channels for both Source A and Source B by
programming the A[3:0]_HS_MAP[0:1] bits of the Source A
input/output mapping register and the B[3:0]_HS_MAP[0:1]
bits of the Source B input/output mapping register, respectively.
The user can independently control the polarity of the eight
input channels by programming the A_SG and B_SG bits of the
source sign select register. This allows a designer to invert the
order of the p and n signals of a given TMDS pair inside the
AD8192 instead of on the PCB.
DDC LOGIC LEVELS
The AD8192 supports the use of flexible (3.3 V, 5 V) logic levels
on the DDC bus. The logic level for the DDC_A and DDC_B
buses are set by the voltage on VREF_AB, and the logic level
for the DDC_COM bus is set by the voltage on VREF_COM.
For example, if the DDC_COM bus is using 5 V I
VREF_COM power supply pin should be connected to a +5 V
power supply. If the DDC_AB buses are using 3.3 V I
the VREF_AB power supply pin should be connected to a
+3.3 V power supply.
2
C, then the
2
C, then
Rev. 0 | Page 14 of 28
AD8192
SERIAL CONTROL INTERFACE
Send the data (eight bits) to be written to the register
RESET
On initial power-up, or at any point during operation, the
AD8192 register set can be restored to the default values by
RESET
pulling the
During normal operation, however, the Tabl e 1 .
pin to low according to the specification in
RESET
pin
must be pulled up to 3.3 V.
WRITE PROCEDURE
To write data to the AD8192 register set, an I2C master (such as
a microcontroller) needs to send the appropriate control signals
to the AD8192 slave device. The signals are controlled by the
2
C master unless otherwise specified. For a diagram of the
I
procedure, see Figure 28. The steps for a write procedure are as
follows:
Send a start condition (while holding the I2C_SCL line
1.
high, pull the I2C_SDA line low).
Send the AD8192 part address (seven bits). The upper six
2.
bits of the AD8192 part address are the static value [100100]
and the LSB is set by Input Pin I2C_ADDR. This transfer
should be MSB first.
Send the write indicator bit (0).
3.
Wait for the AD8192 to acknowledge the request.
4.
Send the register address (eight bits) to which data is to be
5.
written. This transfer should be MSB first.
Wait for the AD8192 to acknowledge the request.
6.
7.
whose address was set in Step 5. This transfer should be
MSB first.
Wait for the AD8192 to acknowledge the request.
8.
9.
Do one of the following:
Send a stop condition (while holding the I2C_SCL
a.
line high, pull the I2C_SDA line high) and release
control of the bus to end the transaction (shown in
Figure 28).
Send a repeated start condition (while holding the
b.
I2C_SCL line high, pull the I2C_SDA line low) and
continue with Step 2 in this procedure to perform
another write.
Send a repeated start condition (while holding the
c.
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.
Send a repeated start condition (while holding the
d.
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.
GENERAL CASE
I2C_SCL
I2C_SDA
EXAMPLE
I2C_SDA
R/W
START FIXE D ADDR PART REGISTER ADDR DATA STOP
ACK ACKADDR
1 2 3 4 5 6 7 8 9
Figure 28. I
2
C Write Procedure
ACK
07050-108
Rev. 0 | Page 15 of 28
AD8192
I2C_SCL
GENERAL CASE
I2C_SDA
EXAMPLE
I2C_SDA
START
FIXED PART
ADDR
ADDR
R/W
ACK
REGISTER ADDR
ACK
SR
FIXED PART
ADDR
ADDR
R/W
DATA STOP
ACK NACK
1 2 3 4 5 6 7 8 9 10 11 12 13
Figure 29. I
READ PROCEDURE
To read data from the AD8192 register set, an I2C master (such
as a microcontroller) needs to send the appropriate control
signals to the AD8192 slave device. The signals are controlled
2
by the I
the procedure, see Figure 29. The steps for a read procedure are
as follows:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
C master unless otherwise specified. For a diagram of
Send a start condition (while holding the I2C_SCL line
high, pull the I2C_SDA line low).
Send the AD8192 part address (seven bits). The upper six
bits of the AD8192 part address are the static value
[100100], and the LSB is set by Input Pin I2C_ADDR. This
transfer should be MSB first.
Send the write indicator bit (0).
Wait for the AD8192 to acknowledge the request.
Send the register address (eight bits) from which data is to
be read. This transfer should be MSB first.
Wait for the AD8192 to acknowledge the request.
Send a repeated start condition (Sr) by holding the
I2C_SCL line high and pulling the I2C_SDA line low.
Resend the AD8192 part address (seven bits) from Step 2.
The upper six bits of the AD8192 part address compose the
static value [100100]. The LSB is set by Input Pin I2C_ADDR.
This transfer should be MSB first.
Send the read indicator bit (1).
Wait for the AD8192 to acknowledge the request.
The AD8192 serially transfers the data (eight bits) held in
the register indicated by the address set in Step 5. This data
is sent MSB first.
Capture the data from the AD8192.
2
C Read Procedure
12.
Do one of the following:
Send a no acknowledge followed by a stop condition
a.
(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 29).
Send a no acknowledge followed by a repeated start
b.
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 Wri t e Pro c edure
section) to perform a write.
Send a no acknowledge followed by a repeated start
c.
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.
Send a no acknowledge followed by a repeated start
d.
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.
7050-109
Rev. 0 | Page 16 of 28
AD8192
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
least significant bit of the AD8192 I
Table 9. Register Map
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Addr. Default
High
Speed
Device
Modes
Auxiliary
Device
Modes
Receiver
Settings
Input
Termination
Control
Receive
Equalizer
Transmitter
Settings
Source
Sign
Control
Source A
Input/
Output
Mapping
Source B
Input/
Output
Mapping
High speed
Auxiliary
switch mode
lock
AUX_LK AUX_EN AUX_CH
Input
RX_PT[7] RX_PT[6] RX_PT[5] RX_PT[4] RX_PT[3] RX_PT[2] RX_PT[1] RX_PT[0]
RX_EQ[7] RX_EQ[6] RX_EQ[5] RX_EQ[4] RX_EQ[3] RX_EQ[2] RX_EQ[1] RX_EQ[0]
Output pre-emphasis
B_SG[3] B_SG[2] B_SG[1] B_SG[0] A_SG[3] A_SG[2] A_SG[1] A_SG[0]
A3_HS_MAP[1] A3_HS_MAP[0] A2_HS_MAP[1] A2_HS_MAP[0] A1_HS_MAP[1] A1_HS_MAP[0] A0_HS_MAP[1] A0_HS_MAP[0]
B3_HS_MAP[1] B3_HS_MAP[0] B2_HS_MAP[1] B2_HS_MAP[0] B1_HS_MAP[1] B1_HS_MAP[0] B0_HS_MAP[1] B0_HS_MAP[0]
2
C part address is set by tying the Pin I2C_ADDR to 3.3 V (I2C_ADDR = 1b) or 0 V (I2C_ADDR = 0b).
switch
enable
HS_EN HS_CH
Auxiliary
switch
enable
Source B input sign select Source A input sign select 0x80 0x00
High speed
Auxiliary
Input termination select 0x11 0x00
Input equalization level select 0x14 0xFF
level select
TX_PE[1] TX_PE[0] TX_PTO TX_OCL
Sourch A high speed input/output mapping 0x81 0xE4
Source B high speed input/output mapping 0x82 0xE4
Output
termination
on/off select
source select
switch
source select
termination
control mode
select
RX_TO
Output
current level
select
0x00 0x40
0x01 0xC0
0x10 0x01
0x20 0x03
Rev. 0 | Page 17 of 28
AD8192
HIGH SPEED DEVICE MODES REGISTER
HS_EN: High Speed (TMDS) Switch Enable Bit
Table 10. HS_EN Description
HS_EN Description
0b High speed channels off, low power/standby mode
1b High speed channel on
HS_CH: High Speed (TMDS) Source Select Bit
Table 11. HS_CH Mapping
HS_CH O[3:0] Description
0b A[3:0] High Speed Source A switched to output
1b B[3:0] High Speed Source B switched to output
AUXILIARY DEVICE MODES REGISTER
AUX_LK: Auxiliary (Low Speed) Switch Mode Lock Bit
Table 12. AUX_LK Description
AUX_LK Description
0b
1b
AUX_EN: Auxiliary (Low Speed) Switch Enable Bit
Table 13. AUX_EN Description
AUX_EN Description
0b
1b Auxiliary switch on
AUX_CH: Auxiliary (Low Speed) Switch Source Select Bit
Table 14. AUX_CH Mapping
AUX_CH AUX_COM[3:0] Description
0b AUX_A[3:0]
1b AUX_B[3:0]
RECEIVER SETTINGS REGISTER
Auxiliary switch lock off, auxiliary source is switched
independently of the high speed source
Auxiliary switch lock on, auxiliary switch source select
is slaved to the high speed switch source select bit
Auxiliary switch off, no low speed input/output to
low speed common input/output connection
Auxiliary Source A switched to
output
Auxiliary Source B switched to
output
INPUT TERMINATION CONTROL REGISTER
RX_PT[x]: High Speed (TMDS) Input Termination x, Select Bit
Table 16. RX_PT[x] Description
RX_PT[x] Description
0b
1b
Input termination mode for TMDS Channel x is
always disconnected
Input termination for TMDS Channel x is always
connected
Table 17. RX_PT[x] Mapping
RX_PT[x] Corresponding Input TMDS Channel
Bit 0 A0
Bit 1 A1
Bit 2 A2
Bit 3 A3
Bit 4 B3
Bit 5 B2
Bit 6 B1
Bit 7 B0
RECEIVE EQUALIZER REGISTER
RX_EQ[x]: High Speed (TMDS) Input x, Equalization Level
Select Bit
Table 18. RX_EQ[x] Description
RX_EQ[x] Description
0b Low equalization (6 dB)
1b High equalization (12 dB)
Table 19. RX_EQ[x] Mapping
RX_EQ[x] Corresponding Input TMDS Channel
Bit 0 A0
Bit 1 A1
Bit 2 A2
Bit 3 A3
Bit 4 B3
Bit 5 B2
Bit 6 B1
Bit 7 B0
RX_TO: High Speed (TMDS) Input Termination Mode Control Select Bit
Table 15. RX_TO Description
RX_TO Description
0b
1b
Input termination mode is manual, individual
terminations can be enabled/disabled according to
settings in the input termination pulse register
Input termination for TMDS Channel x is always
connected
Rev. 0 | Page 18 of 28
AD8192
TRANSMITTER SETTINGS REGISTER
TX_PE[x]: High Speed (TMDS) Output Pre-Emphasis Level Select Bus (For All TMDS Channels)
Table 20. TX_PE[x] Description
TX_PE[x] Description
00b No pre-emphasis (0 dB)
01b Low pre-emphasis (2 dB)
10b Medium pre-emphasis (4 dB)
11b High pre-emphasis (6 dB)
TX_PTO: High Speed (TMDS) Output Termination On/Off Select Bit (For All Channels)
Table 21. TX_PTO Description
TX_PTO Description
0b Output termination off
1b Output termination on
TX_OCL: High Speed (TMDS) Output Current Level Select Bit (For All Channels)
Table 22. TX_OCL Description
TX_OCL Description
0b Output current set to 10 mA
1b Output current set to 20 mA
SOURCE SIGN CONTROL REGISTER
A_SG[x]: High Speed (TMDS) Input A, Channel x Sign Select Bits
Defines the input/input complement polarity of the Channel x.
Table 23. A_SG[x] Description
A_SG[x] Description
0b Channel sign is positive
1b Channel sign is inverted
Table 24. A_SG[x] Mapping
A_SG[x] OP[x] ON[x]
0b IP_A[x] IN_A[x]
1b IN_A[x] IP_A[x]
B_SG[x]: High Speed (TMDS) Input B, Channel x Sign Select Bits
These bits define the input/input complement polarity of the
Channel x.
Table 25. B_SG[x] Description
B_SG[x] Description
0b Channel sign is positive
1b Channel sign is inverted
Table 26. B_SG[x] Mapping
B_SG[x] OP[x] ON[x]
0b IP_B[x] IN_B[x]
1b IN_B[x] IP_B[x]
SOURCE A INPUT/OUTPUT MAPPING REGISTER
A[x]_HS_MAP[1:0]: High Speed (TMDS) Input A, Output Channel x, Select Bits
These bits define the input/output mapping of the high speed
channels when Source A is selected.
Table 27. A[x]_HS_MAP[1:0] Mapping
A[x]_HS_MAP[1:0] O[x]
00b A0
01b A1
10b A2
11b A3
SOURCE B INPUT/OUTPUT MAPPING REGISTER
B[x]_HS_MAP[1:0]: High speed (TMDS) Input B, Output Channel x, Select Bits
These bits define the input/output mapping of the high speed
channels when Source B is selected.
Table 28. B[x]_HS_MAP[1:0] Mapping
B[x]_HS_MAP[1:0] O[x]
00b B0
01b B1
10b B2
11b B3
Rev. 0 | Page 19 of 28
AD8192
V
V
APPLICATIONS INFORMATION
TMDS
D2+
D2–
D1+
D1–
D0+
D0–
CLK+
CLK–
+5V
HPD
DDC_SCL
DDC_SDA
CEC
D2+
D2–
D1+
D1–
D0+
D0–
CLK+
CLK–
+5V
HPD
DDC_SCL
DDC_SDA
CEC
ESD
PROT.
(OPTIONAL)
0.01uF
ESD
PROT.
(OPTIONAL)
2kΩ
EDID
EEPROM
2kΩ
1kΩ
TMDS
1kΩ
47kΩ47
47kΩ47
IPA3
INA3
IPA2
INA2
IPA1
INA1
IPA0
INA0
+5
+3.3
AMUXVCC
VREF_AB
AVCC, DVCC
VTTI, VTTO
AD8192
OUTP3
kΩ
kΩ
HPD_A
SCL_A
SDA_A
CEC_I/O
IPB3
INB3
IPB2
INB2
IPB1
INB1
IPB0
INB0
HPD_B
SCL_B
SDA_B
OUTN3
OUTP2
OUTN2
OUTP1
OUTN1
OUTP0
OUTN0
VREF_COM
SCL_COM
SDA_COM
CEC_O/I
I2C_SCL
I2C_SDA
I2C_ADDR
AVEE, DVEE
TMDS
+3.3V OR +5V
+3.3V
1kΩ
D2+
D2–
D1+
D1–
D0+
D0–
CLK+
CLK–
HDMI
2kΩ2kΩ
2kΩ2kΩ
RECEIVER
MCU
0.01uF
EDID
EEPROM
Figure 30. Typical Simplified Schematic
The AD8192 is an HDMI/DVI switch featuring equalized TMDS
inputs, pre-emphasized TMDS outputs, and buffered auxiliary
signals. 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 1.3a transmit and receive compliant.
PINOUT
By default, the AD8192 is designed to have an HDMI/DVI
receiver pinout at its input and a transmitter pinout at its
output. However, the input/output mapping of the AD8192 is
completely programmable via the serial control interface. This
allows a designer to integrate the AD8192 into virtually any
application without requiring the use of vias on the TMDS
traces in the PCB layout.
In addition to 12 dB of input equalization, the AD8192 provides
up to 6 dB of output pre-emphasis that boosts the output TMDS
Rev. 0 | Page 20 of 28
07050-030
signals and allows the AD8192 to precompensate when driving
long PCB traces or output cables. The net effect of the input
equalization and output pre-emphasis of the AD8192 is that the
AD8192 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.
The AD8192 also provides a distinct advantage in receive-type
applications because it is a fully buffered HDMI/DVI switch;
the AD8192 fully buffers and electrically decouples the outputs
from the inputs for both the TMDS and the auxiliary lines. Therefore, the effects of any vias placed on the output signal lines are
not seen at the input of the AD8192. The programmable output
terminations also improve signal quality at the output of the
AD8192. Thus, the PCB designer has significantly increased
flexibility in the placement and routing of the output signal path
with the AD8192 over other solutions.
AD8192
CABLE LENGTHS AND EQUALIZATION
The AD8192 offers two levels of programmable equalization
for the high speed inputs: 6 dB and 12 dB. The equalizer of
the AD8192 supports video data rates of up to 2.25 Gbps and
can equalize more than 20 meters of 24 AWG HDMI cable at
2.25 Gbps, which corresponds to the video format 1080p with
12-bit 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 AD8192 equalization level can be set to high, or 12 dB,
for all input cable configurations at all data rates, without degrading
the signal integrity.
AD8192
Figure 31. AD8192 as a Front Panel Buffer for an HDTV
HDMI SWITCHER
In home theatre applications where more HDMI inputs are
needed, a multiple input HDMI switcher can be used to extend
the number of available HDMI inputs. This switch can be contained within an audio/video receiver (AVR) or as a standalone
unit. The AD8192 can be cascaded to create larger arrays as
shown in Figure 32.
HDTV SET
MAIN PCB
HDMI RX
CABLE
07050-031
TMDS OUTPUT RISE/FALL TIMES
The TMDS outputs of the AD8192 are designed for optimal
performance even when external components are connected
such as external ESD protection, common-mode filters, and
the HDMI connector. In applications where the output of the
AD8192 is connected to an HDMI output connector, additional
ESD protection is recommended. The capacitance of the additional
ESD protection circuits for the TMDS outputs should be as low
as possible. In a typical application, the output rise/fall times are
compliant with the HDMI 1.3a specification at the output of the
HDMI connector.
FRONT PANEL BUFFER FOR ADVANCED TV
A front panel input provides easy access to an HDMI connector
for connecting an HD camcorder or video game console to an
HDTV. In designs where the main PCB is not near the side or
front of the HDTV, a front panel buffer must be connected to
the main board by a cable. The AD8192 enables the implementation of a front or side panel HDMI input for an HDTV by
buffering the HDMI signals and compensating for the cable
interconnect to the main board.
EQ
AD8192
EQ
EQ
AD8192
EQ
EQ
AD8192
EQ
07050-132
Figure 32. AD8192 Cascaded as a 4:1 HDMI Switcher
CASCADING MULTIPLE DEVICES
Unlike traditional I2C bidirectional buffers, the DDC/CEC
buffers in the AD8192 can be cascaded to create larger arrays
such as those shown in Figure 32. The TMDS signals can also
be cascaded, although it is important to use caution because
cascading high gain equalizers can increase the output jitter
beyond acceptable limits. In such cases, set the programmable
equalizer in the AD8192 to low (6 dB).
Rev. 0 | Page 21 of 28
AD8192
PCB LAYOUT GUIDELINES
The AD8192 switches 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 PCB.
The first group of signals carries the AV data. HDMI/DVI video
signals are differential, unidirectional, and high speed (up to
2.25 Gbps). The channels that carry the video data must be
controlled impedance, terminated at the receiver, and capable of
operating up to at least 2.25 Gbps. 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 AD8192 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 fully specified by
the HDMI standard but its inclusion improves the overall system
signal integrity.
The 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 I
and HDCP encryption keys between the source and the sink),
the CEC line, and the 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 I
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 each input of the AD8192 are
identical. No concession was made to lower the bandwidth of
the fourth channel for the pixel clock; therefore, any channel
can be used for any TMDS signal. An external 2 k pull-down
resistor on the TMDS CLKN signal is recommended for
improved noise immunity as shown in Figure 30.
The AD8192 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 is 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 AD8192, all four high
2
C bus used to send EDID information
2
C bus standard and do not have
Rev. 0 | Page 22 of 28
speed signals should be routed on a PCB in accordance with the
same RF layout guidelines.
Layout for the TMDS Signals
The TMDS differential pairs can be either 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 PCB 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. Leave enough space between the differential
pairs of a given group to prevent the n of one pair from coupling
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 traces (either Input A, Input B, or
the outputs) 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.
Minimizing intrapair 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.
Though the AD8192 features input equalization and output preemphasis, minimizing the length of the TMDS traces is needed
to reduce overall system signal degradation. Commonly used
PCB material, such as FR4, is lossy at high frequencies, therefore, long traces on the circuit board increase signal attenuation,
resulting in decreased signal swing and increased jitter through
intersymbol interference (ISI).
AD8192
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 PCB 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 a100 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 needs to 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 AD8192. 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 33.
THROUGH-HOL E VIAS
SILKSCREEN
LAYER 1: SIGNAL (MICRO STRI P)
PCB DIELECTRI C
LAYER 2: GND (REFERENCE PLANE)
PCB DIELECTRI C
LAYER 3: PWR
(REFERENCE PLANE )
PCB DIELECTRI C
LAYER 4: SIGNAL (MICRO STRI P)
SILKSCREEN
KEEP REFERENCE PL ANE
ADJACENT TO SI GNAL ON ALL
LAYERS TO P ROVIDE CONTINUOUS
GROUND CURRENT RETURN PATH.
Figure 33. Example Routing of Reference Plane
07050-032
TMDS Terminations
The AD8192 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.
The output termination resistors of the AD8192 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 AD8192
TMDS outputs on multiple layers of the PCB without severely
degrading the quality of the output signal.
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).
The DDC and CEC signals are buffered and switched through
the AD8192, and the HPD signal is pulsed low by the AD8192.
These signals 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 AD8192 is being used.
For example, the maximum speed of signals present on the
2
auxiliary lines are 100 kHz I
any layout that enables 100 kHz I
C data on the DDC lines, therefore,
2
C to be passed over the DDC
bus should suffice. The HDMI 1.3a 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 AD8192, or an
equivalent receiver. There is a similar limit of 150 pF of input
capacitance for the CEC line. The benefit of the AD8192 is that
it buffers these lines, isolating the output capacitance so that
only the capacitance at the input side contributes to the specified limit. Good board design is still required, however.
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
Rev. 0 | Page 23 of 28
AD8192
the amount of parasitic trace capacitance. An example of the
board stackup is shown in Figure 34.
W3W 3W
SILKSCREEN
LAYER 1: SIGNAL (MICROSTRIP)
PCB DIEL ECTRI C
LAYER 2: GND (REFERENCE PLANE)
PCB DIEL ECTRI C
LAYER 3: PWR (REFERENCE PLANE)
PCB DIEL ECTRI C
LAYER 4: SIGNAL (MICROSTRIP)
SILKSCREEN
REFERENCE LAYER
RELIEVED UNDERNEAT H
MICROSTRIP
Figure 34. 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 AD8192 is powered up, the DDC/CEC inputs of the
selected channel are actively buffered and routed to the outputs,
and the unselected auxiliary inputs are high impedance. When
the AD8192 is powered off, all DDC/CEC inputs are placed in a
high impedance state. This prevents contention on the DDC
bus, enabling a design to include an EDID in front of the AD8192.
Power Supplies
The AD8192 has five separate power supplies referenced to
two separate grounds. The supply/ground pairs are
AV C C /AV E E
•
•
VTTI/AVEE
•
VTTO/AVEE
•
DVCC/DVEE
•
AMUXVCC/DVEE
•
VREF_AB/DVEE
VREF_COM/DVEE
•
07050-033
The AVCC/AVEE (3.3 V) and DVCC/DVEE (3.3 V) supplies
power the core of the AD8192. The VTTI/AVEE supply (3.3 V)
powers the input termination. Similarly, the VTTO/AVEE supply
(3.3 V) powers the output termination. The AMUXVCC/ DVEE
supply (3.3 V to 5 V) powers the auxiliary multiplexer core. The
VREF_COM and VREF_AB supplies determine the logic levels
on the corresponding DDC buses. For example, if the DDC_COM
2
bus is using 5 V I
C, then VREF_COM should be connected to
+5 V relative to DVEE. If the DDC_AB buses are using 3.3 V
2
C, then VREF_AB should be connected to +5 V relative to DVEE.
I
In a typical application, connect all pins labeled AVEE or DVEE
directly to ground. Likewise, connect all pins labeled AVCC,
DVCC, VTTI, or VTTO to 3.3 V, and tie Pin AMUXVCC to
5 V. VREF_AB and VREF_COM can be tied to either 3.3 V
or 5 V, depending on the application. The supplies can also be
powered individually, but care must be taken to ensure that
each stage of the AD8192 is powered correctly.
Power Supply Bypassing
The AD8192 requires minimal supply bypassing. When
powering the supplies individually, place a 0.01 F capacitor
between each 3.3 V supply pin (AVCC, DVCC, VTTI, and
VTTO) and ground, and place a 0.1 F capacitor between each
additional supply pin (AMUXVCC, VREF_AB, and VREF_COM)
and ground to filter out supply noise. Generally, place bypass
capacitors near the power pins and connect them 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.
In applications where the AD8192 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 F, and one 4.7 F
capacitors. If the AMUXVCC, VREF_AB, and VREF_COM
connections are all powered by a single 5 V supply, it is sufficient
to use a single 0.1 F to bypass all three connections. The capacitors should via down directly to the supply planes and be
placed within a few centimeters of the AD8192.
Rev. 0 | Page 24 of 28
AD8192
OUTLINE DIMENSIONS
PAD
0.30
0.23
0.18
PIN 1
INDICATOR
56
1
4.95
4.80 SQ
4.65
PIN 1
INDICATOR
8.00
BSC SQ
TOP
VIEW
7.75
BSC SQ
0.60 MAX
0.60 MAX
43
42
*
EXPOSED
(BOTTOM VIEW)
0.50
0.40
0.30
1.00
12° MAX
0.85
0.80
SEATING
PLANE
*
NOTE:
THE AD8192 HAS A CONDUCTIV E 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 ELECTRI CALLY CONNECTED TO AVEE. IT IS RECOMMENDED T HAT NO PCB SIGNAL
TRACES OR VI AS BE LOCATED UNDER THE PACKAGE THAT COULD COM E IN CONTACT WITH THE CONDUCTIVE
SLUG. ATTACHING THE SLUG TO AN AVEE PLANE REDUCES T HE JUNCTION TEMP E RATURE OF THE
DEVICE WHI CH MAY BE BENEFICIAL IN HIGH TE M P ERATURE ENVIRO NM E NTS.
0.80 MAX
0.65 TYP
0.50 BSC
COMPLIANT TO JEDEC STANDARDS MO-220-VL LD-2
0.20 REF
0.05 MAX
0.02 NOM
29
28
COPLANARITY
0.08
6.50
REF
Figure 35. 56-Lead Lead Frame Chip Scale Package [LFCSP_VQ]
14
15
0.30 MIN
033108-A
8 mm × 8 mm Body, Very Thin Quad
(CP-56-3)
Dimensions shown in millimeters
ORDERING GUIDE
Package
Model Temperature Range Package Description
AD8192ACPZ1 −40°C to +85°C 56-Lead Lead Frame Chip Scale Package [LFCSP_VQ] CP-56-3
AD8192ACPZ-RL71 −40°C to +85°C 56-Lead Lead Frame Chip Scale Package [LFCSP_VQ], Reel 7 CP-56-3 750
AD8192-EVALZ1 Evaluation Board
1
Z = RoHS Compliant Part.
Option Ordering Quantity
Rev. 0 | Page 25 of 28
AD8192
NOTES
Rev. 0 | Page 26 of 28
AD8192
NOTES
Rev. 0 | Page 27 of 28
AD8192
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.
©2008 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D07050-0-5/08(0)
Rev. 0 | Page 28 of 28
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