4:1 HDMI/DVI Switch with Equalization AD8197A FUNCTIONAL BLOCK DIAGRAM PARALLEL SERIAL I2C_SDA I2C_SCL I2C_ADDR[2:0] 2 3 RESET AD8197A 2 CONFIG INTERFACE AVCC DVCC AMUXVCC AVEE DVEE CONTROL LOGIC VTTI + IP_A[3:0] IN_A[3:0] – + IP_B[3:0] IN_B[3:0] – + IP_C[3:0] IN_C[3:0] – + IP_D[3:0] IN_D[3:0] – VTTO 4 4 4 4 4 4 SWITCH CORE EQ PE + OP[3:0] – ON[3:0] 4 4 HIGH SPEED VTTI AUX_A[3:0] AUX_B[3:0] AUX_C[3:0] AUX_D[3:0] 4 4 BUFFERED 4 4 4 SWITCH CORE 4 4 LOW SPEED UNBUFFERED AUX_COM[3:0] 07014-001 BIDIRECTIONAL Figure 1. TYPICAL APPLICATION GAME CONSOLE MEDIA CENTER HDTV SET HDMI RECEIVER APPLICATIONS SET-TOP BOX DVD PLAYER AD8197A Multiple input displays Projectors A/V receivers Set-top boxes Advanced television (HDTV) sets 04:20 07014-002 4 inputs, 1 output HDMI/DVI link Enables HDMI 1.3-compliant receiver Pin-to-pin compatible with the AD8191A 4 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) 4 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 2 additional signals Output disable feature Reduced power dissipation Removable output termination Allows building of larger arrays 2 AD8197A devices support HDMI/DVI dual-link Standards compatible: HDMI receiver, HDCP, DVI Serial (I2C slave) and parallel control interface 100-lead, 14 mm × 14 mm LQFP, Pb-free package PP_CH[1:0] PP_OTO PP_OCL PP_EQ PP_EN PP_PRE[1:0] FEATURES Figure 2. Typical HDTV Application GENERAL DESCRIPTION PRODUCT HIGHLIGHTS The AD8197A 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 to allow the construction of larger arrays using the wire-OR technique. 1. The AD8197A is provided in a 100-lead LQFP, Pb-free, surfacemount package, specified to operate over the −40°C to +85°C temperature range. 3. 2. Supports data rates up to 2.25 Gbps, enabling 1080p deep color (12-bit color) HDMI formats, and greater than UXGA (1600 × 1200) DVI resolutions. Input cable equalizer enables use of long cables at the input (more than 20 meters of 24 AWG cable at 2.25 Gbps). Auxiliary switch routes a DDC bus and two additional signals for a single-chip, HDMI 1.3 receive-compliant solution. 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. AD8197A TABLE OF CONTENTS Features .............................................................................................. 1 Read Procedure........................................................................... 16 Applications....................................................................................... 1 Switching/Update Delay............................................................ 16 Functional Block Diagram .............................................................. 1 Parallel Control Interface .............................................................. 17 Typical Application........................................................................... 1 Serial Interface Configuration Registers ..................................... 18 General Description ......................................................................... 1 High Speed Device Modes Register......................................... 19 Product Highlights ........................................................................... 1 Auxiliary Device Modes Register............................................. 19 Revision History ............................................................................... 2 Receiver Settings Register ......................................................... 19 Specifications..................................................................................... 3 Input Termination Pulse Register 1 and Register 2 ............... 19 Absolute Maximum Ratings............................................................ 5 Receive Equalizer Register 1 and Register 2 ........................... 20 Thermal Resistance ...................................................................... 5 Transmitter Settings Register.................................................... 20 Maximum Power Dissipation ..................................................... 5 Parallel Interface Configuration Registers .................................. 21 ESD Caution.................................................................................. 5 High Speed Device Modes Register......................................... 22 Pin Configuration and Function Descriptions............................. 6 Auxiliary Device Modes Register............................................. 22 Typical Performance Characteristics ............................................. 9 Receiver Settings Register ......................................................... 22 Eye Diagrams ................................................................................ 9 Input Termination Pulse Register 1 and Register 2 ............... 22 Performance Graphs .................................................................. 11 Receive Equalizer Register 1 and Register 2 ........................... 22 Theory of Operation ...................................................................... 13 Transmitter Settings Register.................................................... 22 Introduction ................................................................................ 13 Application Information................................................................ 23 Input Channels............................................................................ 13 Pinout........................................................................................... 23 Output Channels ........................................................................ 13 Cable Lengths and Equalization............................................... 23 Auxiliary Switch.......................................................................... 14 PCB Layout Guidelines.............................................................. 24 Serial Control Interface.................................................................. 15 Outline Dimensions ....................................................................... 28 Reset ............................................................................................. 15 Ordering Guide .......................................................................... 28 Write Procedure.......................................................................... 15 REVISION HISTORY 11/07—Revision 0: Initial Version Rev. 0 | Page 2 of 28 AD8197A 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 52 95 5 35 72 3.2 40 60 110 40 40 80 7 0.01 44 66 122 54 46 90 8 0.1 mA mA mA mA mA mA mA mA Outputs disabled Outputs enabled, no pre-emphasis Outputs enabled, maximum pre-emphasis 115 384 704 271 574 910 361 671 1050 mW mW mW 200 1.5 ms ms ns DVCC AMUXVCC POWER DISSIPATION 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 28 AD8197A Parameter SERIAL CONTROL INTERFACE 5 Input High Voltage, VIH Input Low Voltage, VIL Output High Voltage, VOH Output Low Voltage, VOL PARALLEL CONTROL INTERFACE Input High Voltage, VIH Input Low Voltage, VIL Conditions/Comments Min Typ Max 2 0.4 V V V V 0.8 V V 0.8 2.4 2 1 Unit Differential interpair skew is measured between the TMDS pairs of a single link. AD8197A output meets the transmitter eye diagram as defined in the DVI Standard Revision 1.0 and the HDMI Standard Revision 1.3. 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 links are deactivated. Minimum and maximum limits are measured at the respective extremes of input termination resistance and input voltage swing. 5 The AD8197A is an I2C slave and its serial control interface is based on the 3.3 V I2C bus specification. 2 Rev. 0 | Page 4 of 28 AD8197A 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 and Parallel Logic Input Voltage Storage Temperature Range Operating Temperature Range Junction Temperature 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 no airflow. Rating 3.7 V 3.7 V ±0.3 V AVCC + 0.6 V AVCC + 0.6 V 5.5 V 2.2 W AVCC − 1.4 V < VIN < AVCC + 0.6 V 2.0 V Table 3. Thermal Resistance Package Type 100-Lead LQFP θJA 56 θJC 19 Unit °C/W MAXIMUM POWER DISSIPATION DVEE − 0.3 V < VIN < AMUXVCC + 0.6 V DVEE − 0.3 V < VIN < DVCC + 0.6 V −65°C to +125°C −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. The maximum power that can be safely dissipated by the AD8197A 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 rating as determined by the coefficients in Table 3. ESD CAUTION Rev. 0 | Page 5 of 28 AD8197A AUX_A0 AUX_A1 AUX_A2 AUX_A3 DVEE AUX_B0 AUX_B1 AUX_B2 AUX_B3 AUX_COM0 AUX_COM1 AUX_COM2 AUX_COM3 AUX_C0 AUX_C1 AUX_C2 AUX_C3 AMUXVCC AUX_D0 AUX_D1 AUX_D2 AUX_D3 PP_EQ PP_EN 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76 PP_OTO 100 99 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS 75 AVCC 74 IP_C3 AVCC 1 IN_B0 2 IP_B0 3 73 IN_C3 AVEE 4 72 AVEE IP_C2 PIN 1 INDICATOR IN_B1 5 71 IP_B1 6 70 IN_C2 VTTI 7 69 VTTI IP_C1 IN_B2 8 68 IP_B2 9 67 IN_C1 AVEE 10 66 AVEE IN_B3 11 IP_B3 12 65 IP_C0 64 AVCC 13 IN_C0 63 IN_A0 AVCC 14 62 IP_D3 IP_A0 15 61 IN_D3 AVEE 16 60 AVEE IP_D2 AD8197A TOP VIEW (Not to Scale) 38 39 40 41 42 43 44 45 46 47 48 49 50 DVCC ON2 OP2 VTTO ON3 OP3 RESET PP_PRE0 PP_PRE1 DVCC PP_OCL I2C_SCL I2C_SDA 07014-003 37 AVEE OP1 51 36 25 ON1 IN_D0 AVEE 35 IP_D0 52 VTTO 53 24 34 23 IP_A3 OP0 IN_A3 33 AVCC ON0 54 32 22 DVCC IN_D1 AVCC 31 IP_D1 55 PP_CH1 56 21 30 20 IP_A2 PP_CH0 IN_A2 29 VTTI DVEE 57 28 19 I2C_ADDR2 IN_D2 VTTI 27 58 26 59 18 I2C_ADDR0 17 IP_A1 I2C_ADDR1 IN_A1 Figure 3. Pin Configuration Table 4. Pin Function Descriptions Pin No. 1, 13, 22, 54, 63, 75 2 3 4, 10, 16, 25, 51, 60, 66, 72 5 6 7, 19, 57, 69 8 9 11 12 14 15 17 18 20 21 23 Mnemonic AVCC IN_B0 IP_B0 AVEE IN_B1 IP_B1 VTTI IN_B2 IP_B2 IN_B3 IP_B3 IN_A0 IP_A0 IN_A1 IP_A1 IN_A2 IP_A2 IN_A3 Type 1 Power HS I HS I Power HS I HS I Power HS I HS I HS I HS I HS I HS I HS I HS I HS I 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. High Speed Input Complement. High Speed Input. High Speed Input Complement. High Speed Input. High Speed Input Complement. High Speed Input. High Speed Input Complement. Rev. 0 | Page 6 of 28 AD8197A Pin No. 24 26 27 28 29, 95 30 31 32, 38, 47 33 34 35, 41 36 37 39 40 42 43 44 45 46 48 49 50 52 53 55 56 58 59 61 62 64 65 67 68 70 71 73 74 76 77 78 79 80 81 82 83 84 85 86 87 88 89 Mnemonic IP_A3 I2C_ADDR0 I2C_ADDR1 I2C_ADDR2 DVEE PP_CH0 PP_CH1 DVCC ON0 OP0 VTTO ON1 OP1 ON2 OP2 ON3 OP3 RESET PP_PRE0 PP_PRE1 PP_OCL I2C_SCL I2C_SDA IN_D0 IP_D0 IN_D1 IP_D1 IN_D2 IP_D2 IN_D3 IP_D3 IN_C0 IP_C0 IN_C1 IP_C1 IN_C2 IP_C2 IN_C3 IP_C3 PP_EN PP_EQ AUX_D3 AUX_D2 AUX_D1 AUX_D0 AMUXVCC AUX_C3 AUX_C2 AUX_C1 AUX_C0 AUX_COM3 AUX_COM2 AUX_COM1 Type 1 HS I Control Control Control Power Control Control Power HS O HS O Power HS O HS O HS O HS O HS O HS O Control Control Control Control Control Control HS I HS I HS I HS I HS I HS I HS I HS I HS I HS I HS I HS I HS I HS I HS I HS I Control Control 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 LS I/O LS I/O LS I/O Description High Speed Input. I2C Address 1st LSB. I2C Address 2nd LSB. I2C Address 3rd LSB. Negative Digital and Auxiliary Multiplexer Power Supply. 0 V nominal. High Speed Source Selection Parallel Interface LSB. High Speed Source Selection Parallel Interface MSB. 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. Normally pulled up to AVCC. High Speed Pre-Emphasis Selection Parallel Interface LSB. High Speed Pre-Emphasis Selection Parallel Interface MSB. High Speed Output Current Level Parallel Interface. I2C Clock. I2C Data. High Speed Input Complement. High Speed Input. High Speed Input Complement. High Speed Input. High Speed Input Complement. High Speed Input. High Speed Input Complement. High Speed Input. High Speed Input Complement. High Speed Input. High Speed Input Complement. High Speed Input. High Speed Input Complement. High Speed Input. High Speed Input Complement. High Speed Input. High Speed Output Enable Parallel Interface. High Speed Equalization Selection Parallel Interface. Low Speed Input/Output. Low Speed Input/Output. Low Speed Input/Output. Low Speed Input/Output. Positive Auxiliary Multiplexer Supply. 5 V typical. Low Speed Input/Output. Low Speed Input/Output. Low Speed Input/Output. Low Speed Input/Output. Low Speed Common Input/Output. Low Speed Common Input/Output. Low Speed Common Input/Output. Rev. 0 | Page 7 of 28 AD8197A Pin No. 90 91 92 93 94 96 97 98 99 100 1 Mnemonic AUX_COM0 AUX_B3 AUX_B2 AUX_B1 AUX_B0 AUX_A3 AUX_A2 AUX_A1 AUX_A0 PP_OTO Type 1 LS I/O LS I/O LS I/O LS I/O LS I/O LS I/O LS I/O LS I/O LS I/O Control Description Low Speed Common Input/Output. Low Speed Input/Output. Low Speed Input/Output. Low Speed Input/Output. Low Speed Input/Output. Low Speed Input/Output. Low Speed Input/Output. Low Speed Input/Output. Low Speed Input/Output. High Speed Output Termination Selection Parallel Interface. HS = high speed, LS = low speed, I = input, O = output. Rev. 0 | Page 8 of 28 AD8197A 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. EYE DIAGRAMS HDMI CABLE AD8197A DIGITAL PATTERN GENERATOR SERIAL DATA ANALYZER EVALUATION BOARD REFERENCE EYE DIAGRAM AT TP1 TP1 TP2 TP3 07014-004 SMA COAX CABLE 07014-007 250mV/DIV 07014-005 250mV/DIV Figure 4. Test Circuit Diagram for Rx Eye Diagram 07014-008 07014-006 250mV/DIV 0.125UI/DIV AT 2.25Gbps Figure 7. Rx Eye Diagram at TP3, EQ = 6 dB (Cable = 2 meters, 30 AWG) 250mV/DIV 0.125UI/DIV AT 2.25Gbps Figure 5. Rx Eye Diagram at TP2 (Cable = 2 meters, 30 AWG) 0.125UI/DIV AT 2.25Gbps 0.125UI/DIV AT 2.25Gbps Figure 6. Rx Eye Diagram at TP2 (Cable = 20 meters, 24 AWG) Figure 8. Rx Eye Diagram at TP3, EQ = 12 dB (Cable = 20 meters, 24 AWG) Rev. 0 | Page 9 of 28 AD8197A HDMI CABLE AD8197A DIGITAL PATTERN GENERATOR SERIAL DATA ANALYZER EVALUATION BOARD REFERENCE EYE DIAGRAM AT TP1 TP1 TP2 TP3 07014-009 SMA COAX CABLE 07014-012 250mV/DIV 07014-010 250mV/DIV Figure 9. Test Circuit Diagram for Tx Eye Diagrams 07014-013 07014-011 250mV/DIV 0.125UI/DIV AT 2.25Gbps Figure 12. Tx Eye Diagram at TP3, PE = 2 dB (Cable = 2 meters, 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 Diagram at TP3, PE = 6 dB (Cable = 10 meters, 28 AWG) Rev. 0 | Page 10 of 28 AD8197A PERFORMANCE GRAPHS 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 07014-014 0 0.4 0 5 10 15 0 25 20 0 5 HDMI CABLE LENGTH (m) 10 07014-017 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 07014-015 200 5 0 800 0 2.4 07014-018 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 07014-019 5 07014-016 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 11 of 28 3.4 50 50 40 40 30 30 JITTER (ps) DJ (p-p) 20 10 07014-020 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 07014-022 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 07014-021 5 110 07014-024 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 07014-023 JITTER (ps) AD8197A 60 80 100 TEMPERATURE (°C) Figure 22. Rise and Fall Time vs. Temperature Rev. 0 | Page 12 of 28 AD8197A 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. The AD8197A has two control interfaces. Users have the option of controlling the part through either the parallel control interface or the I2C® serial control interface. The AD8197A has eight user-programmable I2C slave addresses to allow multiple AD8197A devices to be controlled by a single I2C bus. A RESET pin is provided to restore the control registers of the AD8197A to default values. In all cases, serial programming values override any prior parallel programming values and any use of the serial control interface disables the parallel control interface until the AD8197A is reset. 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 input terminations can be optionally disconnected for approximately 100 ms following a source switch. The user can program which of the 16 high speed input channels employs this feature by selectively programming the associated RX_PT bits in the input termination pulse registers through the serial control interface. 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 terminations are enabled and cannot be switched when programming the AD8197A through the parallel control interface. 50Ω IP_xx IN_xx 50Ω CABLE EQ AVEE 07014-025 The AD8197A is a pin-to-pin HDMI 1.3 receive-compliant replacement for the AD8191A. The primary function of the AD8197A is to switch one of four (HDMI or DVI) 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 25. High Speed Input Simplified Schematic 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 through the serial control interface. Alternately, the user can globally control the equalization level of all eight high speed input channels by setting the PP_EQ pin of the parallel control interface. 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 AD8197A can be set to 12 dB without degrading the signal integrity, even for short input cables. At the 12 dB setting, the AD8197A can equalize more than 20 meters of 24 AWG cable at 2.25 Gbps. OUTPUT CHANNELS Each high speed output differential pair is terminated to the 3.3 V VTTO power supply through two 50 Ω on-chip resistors (see Figure 26). This termination is user-selectable; it can be turned on or off by programming the TX_PTO bit of the transmitter settings register through the serial control interface, or by setting the PP_OTO pin of the parallel control interface. The output termination resistors of the AD8197A 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 AD8197A TMDS outputs on multiple layers of the PCB without severely degrading the quality of the output signal. The AD8197A 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 through the serial control interface or by setting the PP_EN pin of the parallel control interface. Larger wire-OR’ed arrays can be constructed using the AD8197A in this mode. Rev. 0 | Page 13 of 28 AD8197A 50Ω 50Ω OPx ONx IOUT 07014-026 DISABLE AVEE Figure 26. High Speed Output Simplified Schematic The AD8197A requires output termination resistors when the high speed outputs are enabled. Termination can be internal and/or external. The internal terminations of the AD8197A are enabled by programming the TX_PTO bit of the transmitter settings register or by setting the PP_OTO pin of the parallel control interface. The internal terminations of the AD8197A default to the setting indicated by PP_OTO 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 through the serial control interface or by setting the PP_OCL pin of the parallel control interface. The output current level defaults to the level indicated by PP_OCL 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 or by setting the PP_OCL pin of the parallel control interface. 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 through the serial control interface, or by setting the PP_PE bus of the parallel control interface. No specific cable length is suggested for a particular pre-emphasis setting because cable performance varies widely between manufacturers. When turning off the AD8197A, care needs to be taken with the AMUXVCC supply to ensure that the auxiliary multiplexer pins remain 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 AD8197A. 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 AD8197A and any downstream circuit. For this configuration, the auxiliary inputs of the powered down AD8197A 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. The AD8197A requires 5 V on its supply pin, AMUXVCC, in order for the AUXMUX channels to be high impedance. When a TV is turned off, it cannot provide such a supply; however, it can be provided from any HDMI source that is plugged into it. A Schottky diode network, as shown in Figure 28, uses the 5 V supply (Pin 18) from any HDMI/DVI source to power AMUXVCC and guarantee high impedance of the auxiliary multiplexer pins. The AMUXVCC supply does not draw any significant static current. The use of diodes ensures that connected HDMI sources do not load this circuit if their 5 V pin is low impedance when turned off. The 100 kΩ resistor ensures that a minimum of current flows through the diodes to keep them forward biased. This precaution does not need to be taken if the DDC peripheral circuitry is connected to the bus downstream of the AD8197A. SOURCE A +5V I<50mA PERIPHERAL CIRCUITRY ½CAUX I<50mA PERIPHERAL CIRCUITRY PERIPHERAL CIRCUITRY 100kΩ I<50mA SOURCE B +5V +5V SOURCE D BAT54L PIN 18 HDMI CONNECTOR PIN 14 DVI CONNECTOR AUX_COM0 ½CAUX AD8197A PERIPHERAL CIRCUITRY 07014-027 AUX_A0 RAUX I<50mA AMUXVCC AUXILIARY SWITCH The auxiliary (low speed) lines have no amplification. They are routed using a passive switch that is bandwidth compatible with the standard speed I2C. The schematic equivalent for this passive connection is shown in Figure 27. +5V INTERNAL (IF ANY) PIN 18 HDMI CONNECTOR PIN 14 DVI CONNECTOR BAT54L BAT54L BAT54L +5V SOURCE C PIN 18 HDMI CONNECTOR PIN 14 DVI CONNECTOR BAT54L PIN 18 HDMI CONNECTOR PIN 14 DVI CONNECTOR Figure 28. Suggested AMUXVCC Power Scheme Figure 27. Auxiliary Channel Simplified Schematic, AUX_A0 to AUX_COM0 Routing Example Rev. 0 | Page 14 of 28 07014-028 VTTO AD8197A SERIAL CONTROL INTERFACE RESET On initial power-up, or at any point in operation, the AD8197A register set can be restored to preprogrammed default values by pulling the RESET pin low in accordance with the specifications in Table 1. During normal operation, however, the RESET pin must be pulled up to 3.3 V. Following a reset, the preprogrammed default values of the AD8197A register set correspond to the state of the parallel interface configuration registers, as listed in Table 18. The AD8197A can be controlled through the parallel control interface until the first serial control event occurs. As soon as any serial control event occurs, the serial programming values, corresponding to the state of the serial interface configuration registers (see Table 5), override any prior parallel programming values, and the parallel control interface is disabled until the part is subsequently reset. 3. 4. 5. 6. 7. 8. 9. WRITE PROCEDURE To write data to the AD8197A register set, an I2C master (such as a microcontroller) needs to send the appropriate control signals to the AD8197A 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: 2. Send a start condition (while holding the I2C_SCL line high, pull the I2C_SDA line low). Send the AD8197A part address (seven bits). The upper four bits of the AD8197A part address are the static value [1001] and the three LSBs are set by Input Pin I2C_ADDR2, Input Pin I2C_ADDR1, and Input Pin I2C_ADDR0 (LSB). This transfer should be MSB first. * I2C_SCL R/W GENERAL CASE I2C_SDA START FIXED PART ADDR ADDR REGISTER ADDR ACK DATA ACK STOP ACK EXAMPLE I2C_SDA 1 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 Diagram Rev. 0 | Page 15 of 28 6 7 8 9 07014-029 1. Send the write indicator bit (0). Wait for the AD8197A to acknowledge the request. Send the register address (eight bits) to which data is to be written. This transfer should be MSB first. Wait for the AD8197A to acknowledge the request. Send the data (eight bits) to be written to the register whose address was set in Step 5. This transfer should be MSB first. Wait for the AD8197A to acknowledge the request. Perform one of the following: 9a. 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). 9b. 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. 9c. 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. 9d. 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. AD8197A I2C_SCL R/W GENERAL CASE I2C_SDA START FIXED PART ADDR R/W ADDR REGISTER ADDR SR ACK FIXED PART ADDR ACK DATA ADDR STOP ACK ACK 9 10 11 12 1 2 3 4 5 6 7 8 13 07014-030 EXAMPLE I2C_SDA 2 Figure 30. I C Read Diagram READ PROCEDURE 2 To read data from the AD8197A register set, an I C master (such as a microcontroller) needs to send the appropriate control signals to the AD8197A 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. Send a start condition (while holding the I2C_SCL line high, pull the I2C_SDA line low). 2. Send the AD8197A part address (seven bits). The upper four bits of the AD8197A part address are the static value [1001] and the three LSBs are set by Input Pin I2C_ADDR2, Input Pin I2C_ADDR1, and Input Pin I2C_ADDR0 (LSB). This transfer should be MSB first. 3. Send the write indicator bit (0). 4. Wait for the AD8197A 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 AD8197A 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 AD8197A part address (seven bits) from Step 2. The upper four bits of the AD8197A part address are the static value [1001] and the three LSBs are set by the Input Pin I2C_ADDR2, I2C_ADDR1 and Input Pin I2C_ADDR0 (LSB). This transfer should be MSB first. 9. Send the read indicator bit (1). 10. Wait for the AD8197A to acknowledge the request. 11. The AD8197A serially transfers the data (eight bits) held in the register indicated by the address set in Step 5. This data is sent MSB first. 12. Acknowledge the data from the AD8197A. 13. Perform one of the following: 13a. 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). 13b. 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 (previous Write Procedure section) to perform a write. 13c. 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. 13d. 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. SWITCHING/UPDATE DELAY There is a delay between when a user writes to the configuration registers of the AD8197A and when that state change takes physical effect. This update delay occurs regardless of whether the user programs the AD8197A via the serial or the parallel control interface. When using the serial control interface, the update delay begins at the falling edge of I2C_SCL for the last data bit transferred, as shown in Figure 29. When using the parallel control interface, the update delay begins at the transition edge of the relevant parallel interface pin. 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 AD8197A 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 AD8197A 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 AD8197A immediately updates and a new delay window begins. Rev. 0 | Page 16 of 28 AD8197A PARALLEL CONTROL INTERFACE The AD8197A can be controlled through the parallel interface using the PP_EN, PP_CH[1:0], PP_EQ, PP_PRE[1:0], PP_OTO, and PP_OCL pins. Logic levels for the parallel interface pins are set in accordance with the specifications listed in Table 1. Setting these pins updates the parallel control interface registers, as listed in Table 18. Following a reset, the AD8197A can be controlled through the parallel control interface until the first serial control event occurs. As soon as any serial control event occurs, the serial programming values override any prior parallel programming values, and the parallel control interface is disabled until the part is subsequently reset. The default serial programming values correspond to the state of the serial interface configuration registers, as listed in Table 5. Note that after changing the status of the channel selection (PP_CH[1:0]), it is necessary to assert a low logic level to RESET to ensure that the channel-select status is properly updated. Rev. 0 | Page 17 of 28 AD8197A SERIAL INTERFACE CONFIGURATION REGISTERS The serial interface configuration registers can be read and written using the I2C serial control interface, Pin I2C_SDA, and Pin I2C_SCL. The least significant bits of the AD8197A I2C part address are set by tying Pin I2C_ADDR2, Pin I2C_ADDR1, and Pin I2C_ADDR0 to 3.3 V (Logic 1) or 0 V (Logic 0). As soon as the serial control interface is used, the parallel control interface is disabled until the AD8197A is reset, as described in the Serial Control Interface section. Table 5. Serial (I2C) Interface Register Map Name Bit 7 High Speed Device Modes Bit 6 High speed channel enable HS_EN Auxiliary switch enable AUX_EN Auxiliary Device Modes Bit 5 0 0 Bit 4 0 0 Bit 3 0 0 Bit 2 0 0 Bit 1 Addr. Default High speed source select 0x00 0x40 HS_CH[1] HS_CH[0] Auxiliary switch source select 0x01 0x40 0x10 0x01 0x11 0x00 0x12 0x00 0x13 0x00 0x14 0x00 0x20 0x03 AUX_CH[1] Receiver Settings Input Termination Pulse Register 1 Input Termination Pulse Register 2 Receive Equalizer 1 Receive Equalizer 2 Transmitter Settings RX_PT[7] Source A and Source B : input termination pulse-on-source switch select (disconnect termination for a short period of time) RX_PT[6] RX_PT[5] RX_PT[4] RX_PT[3] RX_PT[2] RX_PT[1] RX_PT[15] Source C and Source D : input termination pulse-on-source switch select (disconnect termination for a short period of time) RX_ PT[14] RX_PT[13] RX_PT[12] RX_PT[11] RX_PT[10] RX_PT[9] RX_EQ[7] RX_EQ[6] RX_EQ[15] RX_EQ[14] Source A and Source B: input equalization level select RX_EQ[5] RX_EQ[4] RX_EQ[3] RX_EQ[2] RX_EQ[1] Source C and Source D: input equalization level select RX_EQ[13] RX_EQ[12] RX_EQ[11] RX_EQ[10] RX_EQ[9] High speed output High speed pre-emphasis level output select termination select TX_PE[1] TX_PE[0] TX_PTO Rev. 0 | Page 18 of 28 Bit 0 AUX_CH[0] High speed channel input termination select RX_TO RX_PT[0] RX_PT[8] RX_EQ[0] RX_EQ[8] High speed output current level select TX_OCL AD8197A HIGH SPEED DEVICE MODES REGISTER RECEIVER SETTINGS REGISTER HS_EN: High Speed (TMDS) Channel Enable Bit RX_TO: High Speed (TMDS) Channels Input Termination On/Off Select Bit Table 6. HS_EN Description HS_EN 0 1 Description High speed channels off, low power/standby mode High speed channels on Table 10. RX_TO Description RX_TO 0 1 HS_CH[1:0]: High Speed (TMDS) Switch Source Select Bus Table 7. HS_CH Mapping HS_CH[1:0] 00 O[3:0] A[3:0] 01 B[3:0] 10 C[3:0] 11 D[3:0] Description High Speed Source A switched to output High Speed Source B switched to output High Speed Source C switched to output High Speed Source D switched to output INPUT TERMINATION PULSE REGISTER 1 AND REGISTER 2 RX_PT[x]: High Speed (TMDS) Input Channel X Pulse-On-Source Switch Select Bit Table 11. RX_PT[x] Description RX_PT[x] 0 1 AUXILIARY DEVICE MODES REGISTER AUX_EN: Auxiliary (Low Speed) Switch Enable Bit Table 8. AUX_EN Description AUX_EN 0 1 AUX_CH[1:0]: Auxiliary (Low Speed) Switch Source Select Bus Table 9. AUX_CH Mapping AUX_COM[3:0] AUX_A[3:0] 01 AUX_B[3:0] 10 AUX_C[3:0] 11 AUX_D[3:0] Description Input termination for TMDS Channel X always connected when source is switched Input termination for TMDS Channel X disconnected for 100 ms when source is switched Table 12. RX_PT[x] Mapping Description Auxiliary switch off Auxiliary switch on AUX_CH[1:0] 00 Description Input termination off Input termination on (can be pulsed on and off according to settings in the input termination pulse register) Description Auxiliary Source A switched to output Auxiliary Source B switched to output Auxiliary Source C switched to output Auxiliary Source D switched to output RX_PT[x] Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8 Bit 9 Bit 10 Bit 11 Bit 12 Bit 13 Bit 14 Bit 15 Rev. 0 | Page 19 of 28 Corresponding Input TMDS Channel B0 B1 B2 B3 A0 A1 A2 A3 C3 C2 C1 C0 D3 D2 D1 D0 AD8197A RECEIVE EQUALIZER REGISTER 1 AND REGISTER 2 TRANSMITTER SETTINGS REGISTER RX_EQ[x]: High Speed (TMDS) Input X Equalization Level Select Bit TX_PE[1:0]: High Speed (TMDS) Output Pre-Emphasis Level Select Bus (For All TMDS Channels) Table 13. RX_EQ[x] Description Table 15. TX_PE[1:0] Description RX_EQ[x] 0 1 TX_PE[1:0] 00 01 10 11 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 Bit 8 Bit 9 Bit 10 Bit 11 Bit 12 Bit 13 Bit 14 Bit 15 Corresponding Input TMDS Channel B0 B1 B2 B3 A0 A1 A2 A3 C3 C2 C1 C0 D3 D2 D1 D0 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 (For 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 (For All Channels) Table 17. TX_OCL Description TX_OCL 0 1 Rev. 0 | Page 20 of 28 Description Output current set to 10 mA Output current set to 20 mA AD8197A PARALLEL INTERFACE CONFIGURATION REGISTERS The parallel interface configuration registers can be directly set using the PP_EN, PP_CH[1:0], PP_EQ, PP_PRE[1:0], PP_OTO, and PP_OCL pins. This interface is only accessible after the part is reset and before any registers are accessed using the serial control interface. The state of each pin is set by tying it to 3.3 V (Logic 1) or 0 V (Logic 0). Table 18. Parallel Interface Register Map Name High Speed Device Modes Bit 7 Auxiliary Device Modes Bit 6 High speed channel enable PP_EN Auxiliary switch enable 1 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 High speed source select 0 0 0 0 PP_CH[1] PP_CH[0] Auxiliary switch source select 0 0 0 0 PP_CH[1] Receiver Settings Input Termination Pulse 1 Input Termination Pulse 2 Receive Equalizer 1 Receive Equalizer 2 Transmitter Settings PP_CH[0] Input termination on/off select (termination always on) 1 0 0 Source A and Source B input termination select (termination always off ) 0 0 0 0 0 0 0 0 Source C and Source D input termination select (termination always off ) 0 0 0 0 0 0 PP_EQ PP_EQ PP_EQ PP_EQ Source A and Source B input equalization level select PP_EQ PP_EQ PP_EQ PP_EQ Source C and Source D input equalization level select PP_EQ PP_EQ PP_EQ PP_EQ PP_EQ High speed output High speed pre-emphasis level output select termination on/off select PP_PE[1] PP_PE[0] PP_OTO PP_EQ Rev. 0 | Page 21 of 28 PP_EQ PP_EQ High speed output current level select PP_OCL AD8197A HIGH SPEED DEVICE MODES REGISTER INPUT TERMINATION PULSE REGISTER 1 AND REGISTER 2 PP_EN: High Speed (TMDS) Channel Enable Bit Table 19. PP_EN Description PP_EN 0 1 Description High speed channels off, low power/standby mode High speed channels on PP_CH[1:0]: High Speed (TMDS) Switch Source Select Bus Table 20. High Speed Switch Mapping PP_CH[1:0] 00 O[3:0] A[3:0] 01 B[3:0] 10 C[3:0] 11 D[3:0] Description High Speed Source A switched to output High Speed Source B switched to output High Speed Source C switched to output High Speed Source D switched to output 10 AUX_C[3:0] 11 AUX_D[3:0] Description Low equalization (6 dB) High equalization (12 dB) PP_PE[1:0]: High Speed (TMDS) Output Pre-Emphasis Level Select Bus (For All TMDS Channels) Table 21. Auxiliary Switch Mapping AUX_B[3:0]0 The input equalization cannot be set individually (per channel) when using the parallel interface; one equalization setting affects all input channels. TRANSMITTER SETTINGS REGISTER PP_CH[1:0]: Auxiliary Switch Source Select Bus 01 PP_EQ: High Speed (TMDS) Input Equalization Level Select Bit (For All TMDS Input Channels) PP_EQ 0 1 The auxiliary (low speed) switch is always enabled when using the parallel interface. AUX_COM[3:0] AUX_A[3:0] RECEIVE EQUALIZER REGISTER 1 AND REGISTER 2 Table 22. PP_EQ Description AUXILIARY DEVICE MODES REGISTER PP_CH[1:0] 00 High speed input (TMDS) channels pulse-on-source switching fixed to off when using the parallel interface. Description Auxiliary Source A switched to output Auxiliary Source B switched to output Auxiliary Source C switched to output Auxiliary Source D switched to output RECEIVER SETTINGS REGISTER High speed (TMDS) channels input termination is fixed to on when using the parallel interface. Table 23. PP_PE[1:0] Description PP_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) PP_OTO: High Speed (TMDS) Output Termination On/Off Select Bit (For All TMDS Channels) Table 24. PP_OTO Description PP_OTO 0 1 Description Output termination off Output termination on PP_OCL: High Speed (TMDS) Output Current Level Select Bit (For All TMDS Channels) Table 25. TX_OCL Description PP_OCL 0 1 Rev. 0 | Page 22 of 28 Description Output current set to 10 mA Output current set to 20 mA AD8197A 07014-031 APPLICATION INFORMATION Figure 31. Layout of the TMDS Traces on the AD8197A Evaluation Board (Only Top Signal Routing Layer is Shown) The AD8197A is an HDMI/DVI switch, featuring equalized TMDS inputs and pre-emphasized TMDS outputs. It is intended for use as a 4:1 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 AD8197A is designed to have an HDMI/DVI receiver pinout at its input and a transmitter pinout at its output, which makes the AD8197A 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 AD8197A 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 AD8197A in an AVR-type application is that all of the high speed signals can be routed on one side (the top side) of the board, as shown in Figure 31. In addition to 12 dB of input equalization, the AD8197A provides up to 6 dB of output pre-emphasis that boosts the output TMDS signals and allows the AD8197A to precompensate when driving long PCB traces or output cables. The net effect of the input equalization and output pre-emphasis of the AD8197A is that the AD8197A can compensate for the signal degradation of both input and output cables; it acts to reopen a closed input data eye and transmits a full-swing HDMI signal to an end receiver. More information on the specific performance metrics of the AD8197A can be found in the Typical Performance Characteristics section. The AD8197A 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 AD8197A on the PCB requires a designer to place vias in the high speed signal path, the AD8197A 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 AD8197A. The programmable output terminations also improve signal quality at the output of the AD8197A. The PCB designer, therefore, has significantly improved flexibility in the placement and routing of the output signal path with the AD8197A over other solutions. CABLE LENGTHS AND EQUALIZATION The AD8197A offers two levels of programmable equalization for the high speed inputs: 6 dB and 12 dB. The equalizer of the AD8197A 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. Rev. 0 | Page 23 of 28 AD8197A The length of cable that can be used in a typical HDMI/DVI application depends on a large number of factors, including: conform to the I2C bus standard and do not have excessive capacitive loading. • TMDS Signals • • • 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 AD8197A equalization level can be set to high, or 12 dB, for all input cable configurations at all data rates, without degrading the signal integrity. PCB LAYOUT GUIDELINES The AD8197A 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 PCB. 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 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 AD8197A provides singleended, 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 control interface. The output terminations can also be enabled or disabled through the parallel control 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 transmission 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 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 is interleaved 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 AD8197A 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. 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 AD8197A. However, the routing between inputs and outputs through the AD8197A is fixed. The AD8197A 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 AD8197A, all four high 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. In some applications, such as using multiple AD8197A devices to construct large input arrays, the use of interlayer vias becomes unavoidable. In these situations, the input termination feature of the AD8197A improves system signal integrity by absorbing reflections. Take care to use vias minimally and to place vias symmetrically for each side of a given differential pair. Furthermore, to prevent unwanted signal coupling and Rev. 0 | Page 24 of 28 AD8197A 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 group of four TMDS channels (Input A, Input B, Input C, Input D, 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. 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 AD8197A features input equalization and output pre-emphasis, the length of the TMDS traces should be minimized to reduce overall 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). 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 AD8197A. This requires a designer to route the TMDS traces on multiple layers of the PCB. When routing differential pairs on multiple layers, it is also necessary to 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) 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. 07014-032 interference, route the TMDS signals away from other signals and noise sources on the PCB. Figure 32. Example Routing of Reference Plane TMDS Terminations 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 a 100 Ω differential impedance. When the traces split apart (to go into a connector, for example) and are no The AD8197A 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 AD8197A 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 AD8197A 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: 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 Rev. 0 | Page 25 of 28 AD8197A AD8197A 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 AD8197A is being used. For example, the maximum speed of signals present on the auxiliary lines is 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 AD8197A, 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 directly under the auxiliary traces significantly decreases the amount of parasitic trace capacitance. An example of the board stackup is shown in Figure 33. 3W W 3W When the AD8197A is powered up, one set of the auxiliary inputs is passively routed to the outputs. In this state, the AD8197A looks like a 100 Ω resistor between the selected auxiliary inputs and the corresponding outputs as illustrated in Figure 27. The AD8197A does not buffer the auxiliary signals, therefore, the input traces, output traces, and the connection through the AD8197A all must be considered when designing a PCB to meet HDMI/DVI specifications. The unselected auxiliary inputs of the AD8197A are placed into a high impedance mode when the device is powered up. To ensure that all of the auxiliary inputs of the AD8197A 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 AD8197A buffers the TMDS signals, allowing a PCB designer to layout the TMDS inputs independently of the outputs. Power Supplies The AD8197A 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 AD8197A. 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 maximum allowed voltage on the auxiliary lines. For example, if the DDC bus is using 5 V I2C, AMUXVCC should be connected to 5 V relative to DVEE. SILKSCREEN LAYER 1: SIGNAL (MICROSTRIP) PCB DIELECTRIC LAYER 2: GND (REFERENCE PLANE) PCB DIELECTRIC LAYER 3: PWR (REFERENCE PLANE) PCB DIELECTRIC LAYER 4: SIGNAL (MICROSTRIP) 07014-033 SILKSCREEN REFERENCE LAYER RELIEVED UNDERNEATH MICROSTRIP 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. 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 AD8197A is powered correctly. Figure 33. Example Board Stackup Rev. 0 | Page 26 of 28 AD8197A Power Supply Bypassing The AD8197A 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. 0.01 μF capacitors, and one 4.7 μF capacitor. The capacitors should via down directly to the supply planes and be placed within a few centimeters of the AD8197A. The AMUXVCC supply does not require additional bypassing. This bypassing scheme is illustrated in Figure 35. DECOUPLING CAPACITORS RECOMMENDED AD8197A EXTRA ADDED INDUCTANCE AUXILIARY LINES 07014-035 NOT RECOMMENDED 07014-034 TMDS TRACES Figure 34. Recommended Pad Outline for Bypass Capacitors In applications where the AD8197A 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 capacitor, one 1000 pF capacitor, two Figure 35. Example Placement of Power Supply Decoupling Capacitors Around the AD8197A Rev. 0 | Page 27 of 28 AD8197A OUTLINE DIMENSIONS 16.20 16.00 SQ 15.80 1.60 MAX 0.75 0.60 0.45 100 1 76 75 PIN 1 14.20 14.00 SQ 13.80 TOP VIEW (PINS DOWN) 0.15 0.05 SEATING PLANE 0.20 0.09 7° 3.5° 0° 0.08 COPLANARITY 51 50 25 26 VIEW A 0.50 BSC LEAD PITCH VIEW A ROTATED 90° CCW 0.27 0.22 0.17 COMPLIANT TO JEDEC STANDARDS MS-026-BED 051706-A 1.45 1.40 1.35 Figure 36. 100-Lead Low Profile Quad Flat Package [LQFP] (ST-100) Dimensions shown in millimeters ORDERING GUIDE Model AD8197AASTZ 1 AD8197AASTZ-RL1 AD8197A-EVALZ1 1 Temperature Range −40°C to +85°C −40°C to +85°C Package Description 100-Lead Low Profile Quad Flat Package [LQFP] 100-Lead Low Profile Quad Flat Package [LQFP], Reel Evaluation Board Package Option ST-100 ST-100 Ordering Quantity 1,000 Z = RoHS Compliant Part. 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. D07014-0-11/07(0) Rev. 0 | Page 28 of 28