xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER JUNE 2007 REV. 1.0.3 GENERAL DESCRIPTION The XRT91L32 is a fully integrated SONET/SDH transceiver for SONET/SDH 622.08 Mbps STS-12/ STM-4 or 155.52 Mbps STS-3/STM-1 applications. The transceiver includes an on-chip Clock Multiplier Unit (CMU), which uses a high frequency PhaseLocked Loop (PLL) to generate the high-speed transmit serial clock from a slower external clock reference. It also provides Clock and Data Recovery (CDR) function by synchronizing its on-chip Voltage Controlled Oscillator (VCO) to the incoming serial data stream. The internal CDR unit can be disabled and bypassed in lieu of an externally recovered received clock from the optical module. Either the internally recovered clock or the externally recovered clock can be used for loop timing applications. The chip provides serial-to-parallel and parallel-to-serial converters using an 8-bit wide LVTTL system interface in both receive and transmit directions. The transmit section includes an option to accept a parallel clock signal from the framer/mapper to synchronize the transmit section timing. The device can internally monitor Loss of Signal (LOS) condition and automatically mute received data upon LOS. An on-chip SONET/SDH frame byte and boundary detector and frame pulse generator offers the ability recover SONET/SDH framing and to byte align the receive serial data stream into the 8-bit parallel bus. APPLICATIONS * SONET/SDH-based Transmission Systems * Add/Drop Multiplexers * Cross Connect Equipment * ATM and Multi-Service Switches, Routers and Switch/Routers * DSLAMS * SONET/SDH Test Equipment * DWDM Termination Equipment FIGURE 1. BLOCK DIAGRAM OF XRT91L32 XRT91L32 STS-12/STM-4 or STS-3/STM-1 TRANSCEIVER PISO (Parallel Input Serial Output) TXDI[7:0] 8 TXOP/N Re-Timer ENB MUX ENB TXPCLK_IO Div by 8 XOR REFCLKP/N TTLREFCLK CMU MUX CDRAUXREFCLK MUX SIPO (Serial Input Parallel Output) RXDO[7:0] ALOOP RLOOPS DLOOP CDR RXIP/N MUX 8 XRXCLKIP/N Div by 8 Control Block CMUFREQSEL LOSEXT DLOSDIS OOF FRAMEPULSE ALOOP DLOOP RLOOPS LOOPTIME Reset STS-12/STS-3 CAP2N CAP2P CAP1N CAP1P CDRDIS Clock Control Loop Filters CDRREFSEL RXPCLKO Exar Corporation 48720 Kato Road, Fremont CA, 94538 * (510) 668-7000 * FAX (510) 668-7017 * www.exar.com XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER xr REV. 1.0.3 FEATURES * Targeted for SONET STS-12/STS-3 and SDH STM-4/STM-1 Applications * Selectable full duplex operation between STS-12/STM-4 standard rate of 622.08 Mbps or STS-3/STM-1 155.52 Mbps * Single-chip fully integrated solution containing parallel-to-serial converter, clock multiplier unit (CMU), serialto-parallel converter, clock data recovery (CDR) functions, and a SONET/SDH frame and byte boundary detection circuit * Ability to disable and bypass onchip CDR for external based received reference clock recovery thru Differential LVPECL input pins XRXCLKIP/N * 8-bit LVTTL parallel data bus paths running at 77.76 Mbps in STS-12/STM-4 or 19.44 Mbps in STS-3/STM-1 mode of operation * Uses Differential LVPECL or Single-Ended LVTTL CMU reference clock frequencies of either 19.44 MHz or 77.76 MHz for both STS-12/STM-1 or STS-3/STM-1 operations * Optional use of 77.76 MHz Single-Ended LVTTL input for independent CDR reference clock operation * Able to Detect and Recover SONET/SDH frame boundary and byte align received data on the parallel bus * Diagnostics features include LOS monitoring and automatic received data mute upon LOS * Provides Local, Remote and Split Loop-Back modes as well as Loop Timing mode * Optional flexibility to re-configure the transmit parallel bus clock output to a clock input and accept timing signal from the framer/mapper device to permit the framer/mapper device time domain to be synchronized with the transceiver transmit timing. * Meets Telcordia, ANSI, Bellcore TR-NWT-000253 and GR-253-CORE, and G.783 ITU-T jitter requirements * Operates at 3.3V with 3.3V I/O * Less than 660mW in STS-3/STM-1 mode or 800mW in STS-12/STM-4 mode Typical Power Dissipation * Package: 10 x 10 x 2.0 mm 100-pin QFP 2 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 DLOOP VDD3.3 CDRREFSEL STS12/STS3 NC TXDI0 TXDI1 GND TXDI2 TXDI3 NC TXIN4 TXDI5 GND TXDI6 TXDI7 GND NC TXPCLK_IO VDD FIGURE 2. 100 QFP PIN OUT OF THE XRT91L32 (TOP VIEW) 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 XRT91L32 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 NC NC NC NC VDD3.3 GND NC NC GND AGND_RX AGND_RX AVDD3.3_RX AVDD3.3_RX AVDD3.3_RX CAP2P CAP2N CAP1N CAP1P AVDD3.3_TX NC AGND_TX AGND_TX VDD3.3 NC TTLREFCLK GND VDD3.3 LOSEXT NC CDRAUXREFCLK VDD3.3 NC NC GND RXDO0 RXD01 GND RXDO2 RXDO3 GND RXDO4 RXDO5 GND RXDO6 RXDO7 GND RXPCLKO FRAMEPULSE VDD3.3 NC 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 RLOOPS VDD3.3 ALOOP RESET LOOPTIME NC NC CMUFREQSEL VDD_PECL TXOP TXON GND NC NC VDD_PECL NC DLOSDIS GND XRXCLKIP XRXCLKIN VDD_PECL OOF CDRDIS RXIP RXIN NC NC VDD3.3 REFCLKP REFCLKN ORDERING INFORMATION PART NUMBER PACKAGE OPERATING TEMPERATURE RANGE XRT91L32IQ-F 100 Pin QFP -40C to +85C 3 xr XRT91L32 REV. 1.0.3 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER TABLE OF CONTENTS GENERAL DESCRIPTION .................................................................................................1 APPLICATIONS ...........................................................................................................................................1 FIGURE 1. BLOCK DIAGRAM OF XRT91L32 ...................................................................................................................................... 1 FEATURES ......................................................................................................................................................2 FIGURE 2. 100 QFP PIN OUT OF THE XRT91L32 (TOP VIEW).......................................................................................................... 3 ORDERING INFORMATION.....................................................................................................................3 TABLE OF CONTENTS ............................................................................................................ I PIN DESCRIPTIONS ..........................................................................................................4 .....................................................................................................................................................................4 HARDWARE CONTROL ....................................................................................................................................4 TRANSMITTER SECTION ..................................................................................................................................6 RECEIVER SECTION ........................................................................................................................................8 POWER AND GROUND ....................................................................................................................................9 1.0 FUNCTIONAL DESCRIPTION .............................................................................................................11 1.1 STS-12/STM-4 AND STS-3/STM-1 MODE OF OPERATION ......................................................................... 11 1.2 CLOCK INPUT REFERENCE FOR CLOCK MULTIPLIER (SYNTHESIZER) UNIT ...................................... 11 TABLE 1: CMU REFERENCE FREQUENCY OPTIONS (DIFFERENTIAL OR SINGLE-ENDED) ................................................................... 11 1.3 DATA LATENCY ............................................................................................................................................. 11 TABLE 2: DATA INGRESS TO DATA EGRESS LATENCY ....................................................................................................................... 11 2.0 RECEIVE SECTION .............................................................................................................................12 2.1 RECEIVE SERIAL INPUT ............................................................................................................................... 12 FIGURE 3. RECEIVE SERIAL INPUT INTERFACE BLOCK ..................................................................................................................... 12 2.2 RECIEVE SERIAL DATA INPUT TIMING ...................................................................................................... 13 FIGURE 4. RECEIVE HIGH-SPEED SERIAL DATA INPUT TIMING DIAGRAM .......................................................................................... 13 TABLE 3: RECEIVE HIGH-SPEED SERIAL DATA INPUT TIMING (STS-12/STM-4 OPERATION) ............................................................. 13 TABLE 4: RECEIVE HIGH-SPEED SERIAL DATA INPUT TIMING (STS-3/STM-1 OPERATION) ............................................................... 13 2.3 RECEIVE CLOCK AND DATA RECOVERY .................................................................................................. 14 TABLE 5: CLOCK DATA RECOVERY UNIT REFERENCE CLOCK SETTINGS ............................................................................................ 14 TABLE 6: CLOCK AND DATA RECOVERY UNIT PERFORMANCE .......................................................................................................... 15 2.3.1 INTERNAL CLOCK AND DATA RECOVERY BYPASS ............................................................................................ 15 FIGURE 5. INTERNAL CLOCK AND DATA RECOVERY BYPASS ............................................................................................................ 15 2.4 EXTERNAL RECEIVE LOOP FILTER CAPACITORS ................................................................................... 16 FIGURE 6. EXTERNAL LOOP FILTERS .............................................................................................................................................. 16 2.5 LOSS OF SIGNAL .......................................................................................................................................... 16 FIGURE 7. LOS DECLARATION CIRCUIT ........................................................................................................................................... 16 2.6 SONET FRAME BOUNDARY DETECTION AND BYTE ALIGNMENT RECOVERY .................................... 17 2.7 RECEIVE SERIAL INPUT TO PARALLEL OUTPUT (SIPO) ......................................................................... 17 FIGURE 8. SIMPLIFIED BLOCK DIAGRAM OF SIPO ........................................................................................................................... 17 2.8 RECEIVE PARALLEL OUTPUT INTERFACE ............................................................................................... 18 FIGURE 9. RECEIVE PARALLEL OUTPUT INTERFACE BLOCK ............................................................................................................. 18 2.9 DISABLE PARALLEL RECEIVE DATA OUTPUT UPON LOS ..................................................................... 18 2.10 RECEIVE PARALLEL DATA OUTPUT TIMING .......................................................................................... 19 FIGURE 10. RECEIVE PARALLEL OUTPUT TIMING ............................................................................................................................ 19 TABLE 7: RECEIVE PARALLEL DATA OUTPUT TIMING (STS-12/STM-4 OPERATION) ......................................................................... 19 TABLE 8: RECEIVE PARALLEL DATA OUTPUT TIMING (STS-3/STM-1 OPERATION) ........................................................................... 19 TABLE 9: PECL AND TTL RECEIVE OUTPUTS TIMING SPECIFICATION .............................................................................................. 20 3.0 TRANSMIT SECTION ..........................................................................................................................21 3.1 TRANSMIT PARALLEL INPUT INTERFACE ................................................................................................. 21 FIGURE 11. TRANSMIT PARALLEL INPUT INTERFACE BLOCK ............................................................................................................. 21 3.2 TRANSMIT PARALLEL DATA INPUT TIMING .............................................................................................. 22 FIGURE 12. TRANSMIT PARALLEL INPUT TIMING .............................................................................................................................. 22 TABLE 10: TRANSMIT PARALLEL DATA INPUT TIMING (STS-12/STM-4 OPERATION)......................................................................... 22 TABLE 11: TRANSMIT PARALLEL DATA INPUT TIMING (STS-3/STM-1 OPERATION)........................................................................... 22 3.3 TRANSMIT PARALLEL INPUT TO SERIAL OUTPUT (PISO) ...................................................................... 23 FIGURE 13. SIMPLIFIED BLOCK DIAGRAM OF PISO ......................................................................................................................... 23 3.4 CLOCK MULTIPLIER UNIT (CMU) AND RE-TIMER ..................................................................................... 23 TABLE 12: CLOCK MULTIPLIER UNIT PERFORMANCE ....................................................................................................................... 23 3.5 LOOP TIMING AND CLOCK CONTROL ........................................................................................................ 24 TABLE 13: LOOP TIMING AND CLOCK RECOVERY CONFIGURATIONS ................................................................................................. 24 I xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 FIGURE 14. LOOP TIMING MODE USING INTERNAL CDR OR AN EXTERNAL RECOVERED CLOCK ....................................................... 25 3.6 TRANSMIT SERIAL OUTPUT CONTROL ..................................................................................................... 25 FIGURE 15. TRANSMIT SERIAL OUTPUT INTERFACE BLOCK .............................................................................................................. 25 4.0 DIAGNOSTIC FEATURES ................................................................................................................... 26 4.1 SERIAL REMOTE LOOPBACK ..................................................................................................................... 26 FIGURE 16. SERIAL REMOTE LOOPBACK ......................................................................................................................................... 26 4.2 DIGITAL LOCAL LOOPBACK ....................................................................................................................... 26 FIGURE 17. DIGITAL LOCAL LOOPBACK ........................................................................................................................................... 26 4.3 ANALOG LOCAL LOOPBACK ...................................................................................................................... 27 FIGURE 18. ANALOG LOCAL LOOPBACK .......................................................................................................................................... 27 4.4 SPLIT LOOPBACK ......................................................................................................................................... 27 FIGURE 19. SPLIT LOOPBACK ......................................................................................................................................................... 27 4.5 EYE DIAGRAM ............................................................................................................................................... 28 FIGURE 20. STS-3/STM-1 EYE DIAGRAM ...................................................................................................................................... 28 FIGURE 21. STS-12/STM-4 EYE DIAGRAM .................................................................................................................................... 28 4.6 SONET JITTER REQUIREMENTS ................................................................................................................. 29 4.6.1 JITTER TOLERANCE: ................................................................................................................................................ 29 FIGURE 22. JITTER TOLERANCE MASK............................................................................................................................................ 29 FIGURE 23. XRT91L32 MEASURED JITTER TOLERANCE AT 622.08 MBPS STS-12/STM-4.............................................................. 30 FIGURE 24. XRT91L32 MEASURED JITTER TOLERANCE AT 155.52 MBPS STS-3/STM-1................................................................ 30 4.6.2 JITTER GENERATION................................................................................................................................................ 31 FIGURE 25. XRT91L32 MEASURED ELECTRICAL PHASE NOISE TRANSMIT JITTER GENERATION AT 622.08 MBPS STS-12/STM4 USING '1010' OUTPUT PATTERN ................................................................................................................................................. 31 5.0 ELECTRICAL CHARACTERISTICS ................................................................................................... 32 ABSOLUTE MAXIMUM RATINGS .................................................................................................................. 32 ABSOLUTE MAXIMUM POWER AND INPUT/OUTPUT RATINGS ......................................................... 32 POWER AND CURRENT DC ELECTRICAL CHARACTERISTICS .................................................................... 32 ................................................................................................................................................................... 32 LVPECL AND LVTTL LOGIC SIGNAL DC ELECTRICAL CHARACTERISTICS...................................... 33 ORDERING INFORMATION .................................................................................................................. 34 PACKAGE DIMENSIONS ................................................................................................ 34 REVISION HISTORY ...................................................................................................................................... 35 II xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 PIN DESCRIPTIONS L32 HARDWARE CONTROL NAME LEVEL TYPE PIN DESCRIPTION RESET LVTTL I 4 Remote Serial Loopback Active "High." When this pin is pulled "High" , the internal state machines are set to their default state. "Low" = Normal Operation "High" = Master Hardware Reset ( minimum 100nS) STS12/STS3 LVTTL I 97 Data Rate Selection Selects SONET/SDH transmission and reception speed rate "Low" = STS-3/STM-1 155.52 Mbps "High" = STS-12/STM-4 622.08 Mbps CMUFREQSEL LVTTL I 8 Clock Multiplier Unit Reference Frequency Select This pin is used to select the frequency of the REFCLKP/N or TTLREFCLK input to the CMU. "Low" = 77.76 MHz reference clock "High" = 19.44 MHz reference clock CMUFREQSEL STS12/ STS3 REFCLKP/N OR TTLREFCLK REFERENCE DATA RATE FREQUENCY 0 0 77.76 MHz STS-3/STM-1 155.52 Mbps 0 1 77.76 MHz STS-12/STM-4 622.08 Mbps 1 0 19.44 MHz STS-3/STM-1 155.52 Mbps 1 1 19.44 MHz STS-12/STM-4 622.08 Mbps NOTE: REFCLKP/N or TTLREFCLK input should be generated from an LVPECL/LVTTL crystal oscillator which has a frequency accuracy better than 20ppm in order for the transmitted data rate frequency to have the necessary accuracy required for SONET systems.. 4 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 NAME LEVEL TYPE PIN DESCRIPTION CDRREFSEL LVTTL I 98 Clock and Data Recover Unit Reference Frequency Select Selects the Clock and Data Recovery Unit reference frequency based on the table below. "Low" = CDR uses CMU's reference clock "High" = CDR reference clock from CDRAUXREFCLK CDRREFSEL STS12/ STS3 DATA RATE CDR uses CMU's reference clock (see CMUFREQSEL pin) 0 NOTE: CDRAUXREFCLK FREQUENCY 1 0 77.76 MHz STS-3/STM-1 155.52 Mbps 1 1 77.76 MHz STS-12/STM-4 622.08 Mbps CDRAUXREFCLK requires accuracy of 77.76 MHz +/- 500ppm. LOOPTIME LVTTL I 5 Loop Timing Mode When the loop timing mode is activated the external reference clock to the input of the Retimer is replaced with the high-speed recovered receive clock from the CDR. "Low" = Disabled "High" = Loop timing Activated CDRDIS LVTTL I 23 Clock and Data Recovery Unit Disable Active "High." Disables internal Clock and Data Recovery unit. Received serial data bypasses the integrated CDR block. RXINP/N is then sampled on the rising edge of externally recovered differential clock XRXCLKIP/N coming from the optical module. "Low" = Internal CDR unit is Enabled "High" = Internal CDR unit is Disabled and Bypassed RLOOPS LVTTL I 1 Serial Remote Loopback The serial remote loopback mode interconnects the receive serial data input to the transmit serial data output. If serial remote loopback is enabled, the 8-bit parallel transmit data input is ignored while the 8-bit parallel receive data output is maintained. "Low" = Disabled "High" = Serial Remote Loopback Mode Enabled NOTE: DLOOP and RLOOPS can be enabled simultaneously to achieve a dual loopback diagnostic feature in normal operation. NC No Connect - 6,7,13, NOTE: No connect 14,16,26, 27,32,33, 50,52,57, 61,73,74, 77,78,79, 80,83,90, 96 5 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 NAME LEVEL TYPE PIN DESCRIPTION ALOOP LVTTL I 3 Analog Local Loopback This loopback feature serializes the 8-bit parallel transmit data input and presents the data to the transmit serial output and in addition it also internally routes the serialized data back to the Clock and Data Recovery block for serial to parallel conversion. The received serial data input is ignored. "Low" = Disabled "High" = Analog Local Loopback Mode Enabled DLOOP LVTTL I 100 DLOOP Local Loopback This digital loopback mode interconnects the 8-bit parallel transmit data input and TXCLK to the 8-bit parallel receive data output and receive RXCLK respectively while maintaining the transmit serial data output. If digital loopback is enabled, the receive serial data input is ignored. "Low" = Disabled "High" = Digital Local Loopback Mode Enabled NOTE: DLOOP and RLOOPS can be enabled simultaneously to achieve a dual loopback diagnostic feature in normal operation. TRANSMITTER SECTION NAME LEVEL TYPE PIN DESCRIPTION TXDI0 TXDI1 TXDI2 TXDI3 TXDI4 TXDI5 TXDI6 TXDI7 LVTTL I 95 94 92 91 89 88 86 85 Transmit Parallel Data Input Transmit Parallel Clock Output Operation The 77.76 Mbps (STS-12/STM-4) / 19.44 Mbps (STS-3/STM-1) 8-bit parallel transmit data should be applied to the transmit parallel bus and simultaneously referenced to the rising edge of the TXPCLK_IO clock output. The 8-bit parallel interface is multiplexed into the transmit serial output interface with the MSB first (TXDI[7:0]). Alternate Transmit Parallel Clock Input Operation When operating is this mode, TXPCLK_IO is no longer a parallel clock output reference but reverses direction and serves as the parallel transmit clock input reference for the PISO (Parallel Input to Serial Output) block. The 77.76 Mbps (STS-12/STM-4) / 19.44 Mbps (STS-3/STM-1) 8-bit parallel transmit data should be applied to the transmit parallel bus and simultaneously referenced to the rising edge of the TXPCLK_IO clock input. TXOP TXON LVPECL Diff O 10 11 Transmit Serial Data Output The transmit serial data stream is generated by multiplexing the 8-bit parallel transmit data input into a 622.08 Mbps STS-12/ STM-4 or 155.52 Mbps STS-3/STM-1 serial data stream. 6 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 TRANSMITTER SECTION NAME LEVEL TYPE PIN DESCRIPTION TXPCLK_O LVTTL O 82 Transmit Parallel Clock Output (77.76/19.44 MHz) Transmit Parallel Clock Output Operation This pin will output a 77.76 MHz (STS-12/STM-4) or 19.44 MHz (STS-3/STM-1) clock output reference for the 8-bit parallel transmit data input TXDI[7:0]. This clock is used by the framer/ mapper device to present the TXDI[7:0] data which the XRT91L32 will latch on the rising edge of this clock. This enables the framer/mapper device and the XRT91L32 transceiver to be in synchronization. REFCLKP REFCLKN LVPECL Diff I 29 30 Reference Clock Input (77.76 MHz or 19.44 MHz) This differential clock input reference is used for the transmit clock multiplier unit (CMU) and clock data recovery (CDR) to provide the necessary high speed clock reference for this device. It will accept either a 77.76 MHz or a 19.44 MHz Differential LVPECL clock source. Pin CMUFREQSEL determines the value used as the reference. See Pin CMUFREQSEL for more details. REFCLKP/N inputs are internally biased to 1.65V. NOTE: TTLREFCLK LVTTL I 56 In the event that TTLREFCLK LVTTL input is used instead of these differential inputs for clock reference, the REFCLKP should be tied to ground. Auxillary Reference Clock Input (77.76 MHz or 19.44 MHz) This LVTTL clock input reference is used for the transmit clock multiplier unit (CMU) and clock data recovery (CDR) to provide the necessary high speed clock reference for this device. It will accept either a 77.76 MHz or a 19.44 MHz LVTTL clock source. Pin CMUFREQSEL determines the value used as the reference. See Pin CMUFREQSEL for more details. NOTE: In the event that REFCLKP/N differential inputs is used instead of this LVTTL input for clock reference, the TTLREFCLK should be tied to ground. 7 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 RECEIVER SECTION NAME LEVEL TYPE PIN DESCRIPTION RXDO0 RXDO1 RXDO2 RXDO3 RXDO4 RXDO5 RXDO6 RXDO7 LVTTL O 35 36 38 39 41 42 44 45 Receive Parallel Data Output 77.76 Mbps (STS-12/STM-4) / 19.44 Mbps (STS-3/STM-1) 8-bit parallel receive data output is updated simultaneously on the rising edge of the RXPCLKO output. The 8-bit parallel interface is de-multiplexed from the receive serial data input MSB first (RXDO[7:0]). The XRT91L32 will output the data on the rising edge of this clock. RXIP RXIN Diff LVPECL I 24 25 Receive Serial Data Input The differential receive serial data stream of 622.08 Mbps STS-12/STM-1 or 155.52 Mbps STS-3/STM-1 is applied to these input pins. XRXCLKIP XRXCLKIN Diff LVPECL I 19 20 External Recovered Receive Clock Input The differential receive serial data stream of 622.08 Mbps STS-12/STM-1 or 155.52 Mbps STS-3/STM-1 is sampled on the rising edge of this externally recovered differential clock coming from the optical module. It is used when the internal CDR unit is disabled and bypassed by the CDRDIS pin. NOTE: In the event that XRXCLKIP/N differential input pins are unused, XRXCLKIP should be tied to VCC with a 1k Ohm pull-up and XRXCLKIN should be tied to Ground with a 1k Ohm pull-down. RXPCLKO LVTTL O 47 Receive Parallel Clock Output (77.76 MHz or 19.44 MHz) 77.76 MHz (STS-12/STM-4) or 19.44 MHz (STS-3/STM-1) clock output reference for the 8-bit parallel receive data output RXDO[7:0]. The parallel received data output bus will be updated on the falling edge of this clock. CDRAUXREFCLK LVTTL I 51 Clock and Data Recovery Auxillary Reference Clock 77.76 MHz 500 ppm auxillary reference clock for the CDR. NOTE: In the event that CDRAUXREFCLK LVTTL input pin is unused, CDRAUXREFCLK should be tied to ground. OOF LVTTL I 22 Out of Frame Input Indicator This level sensitive input pin is used to initiate frame detection and byte alignment recovery when OOF is declared by the downstream device. When this pin is held High, FRAMEPULSE will pulse for a single RXPCLKO period upon the detection of every third frame alignment A2 byte in the incoming SONET/SDH Frame. "Low" = Normal Operation "High" = OOF Indication initiating frame detection and byte boundary recovery and activating FRAMEPULSE FRAMEPULSE LVTTL O 48 Sonet Frame Alignment Pulse This pin will generate a single pulse for an RXPCLKO clock period upon the detection of the third frame alignment A2 byte whenever the OOF input pin is held High. The parallel received data output bus will then be byte aligned to this newly recovered SONET/SDH frame. 8 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 NAME LEVEL TYPE PIN DESCRIPTION CAP1P CAP2P Analog - 63 66 CDR Non-Inverting External Feeback Capacitor C1 = 0.47F 10% tolerance (Isolate from noise and place close to pin) CAP1N CAP2N Analog - 64 65 CDR Inverting External Feeback Capacitor C2 = 0.47F 10% tolerance (Isolate from noise and place close to pin) DLOSDIS LVTTL I 17 LOS (Los of Signal) Detect Disable Disables internal LOS monitoring and automatic muting of RXDO[7:0] upon LOS detection (according to gating shown in Figure 7.) LOS is declared when a string of 128 consecutive zeros occur on the line. LOS condition is cleared when the 16 or more pulse transitions is detected for 128 bit period sliding window. "Low" = Monitor and Mute received data upon LOS declaration "High" = Disable internal LOS monitoring (see Figure 7 for logic operation.) LOSEXT SE-LVPECL I 53 LOS or Signal Detect Input from Optical Module Active "Low." When active, this pin can force the received data output bus RXDO[7:0] to a logic state of '0' per Figure 7. "Low" = Forced LOS "High" = Normal Operation POWER AND GROUND NAME TYPE PIN DESCRIPTION VDD3.3 PWR 2,28,31,49,54, 58,76,99,81 3.3V CMOS Power Supply VDD3.3 should be isolated from the analog VDD power supplies. Use a ferrite bead along with an internal power plane separation. The VDD3.3 power supply pins should have bypass capacitors to the nearest ground. For best results, refer to Application notes about general board layout guidelines. AVDD3.3_TX PWR 62 Analog 3.3V Transmitter Power Supply AVDD3.3_TX should be isolated from the digital power supplies. For best results, use a ferrite bead along with an internal power plane separation. The AVDD3.3_TX power supply pins should have bypass capacitors to the nearest ground. AVDD3.3_RX PWR 67,,68,69 Analog 3.3V Receiver Power Supply AVDD3.3_RX should be isolated from the digital power supplies. For best results, use a ferrite bead along with an internal power plane separation. The AVDD3.3_RX power supply pins should have bypass capacitors to the nearest ground. VDD_LVPECL PWR 9,15,21 3.3V Input/Output LVPECL Bus Power Supply These pins require a 3.3V potential voltage for properly biasing the Differential LVPECL input and output pins. AGND_TX PWR 59,60 Transmitter Analog Ground for 3.3V Analog Power Supplies It is recommended that all ground pins of this device be tied together. 9 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER NAME TYPE PIN AGND_RX PWR 70,71 GND GND REV. 1.0.3 DESCRIPTION Receiver Analog Ground for 3.3V Analog Power Supplies It is recommended that all ground pins of this device be tied together. 12,18,34,37,40,43,46,55, Power Supply and Thermal Ground 72,75,84,87,93 It is recommended that all ground pins of this device be tied together. 10 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 1.0 FUNCTIONAL DESCRIPTION The XRT91L32 transceiver is designed to operate with a SONET Framer/ASIC device and provide a highspeed serial interface to optical networks. The transceiver converts 8-bit parallel data running at 77.76 Mbps (STS-12/STM-4) or 19.44 Mbps (STS-3/STM-1) to a serial Differential LVPECL bit stream at 622.08 Mbps or 155.52 Mbps and vice-versa. It implements a clock multiplier unit (CMU), SONET/SDH serialization/deserialization (SerDes), receive clock and data recovery (CDR) unit and a SONET/SDH frame and byte boundary detection circuit. The transceiver is divided into Transmit and Receive sections and is used to provide the front end component of SONET equipment, which includes primarily serial transmit and receive functions. 1.1 STS-12/STM-4 and STS-3/STM-1 Mode of Operation Functionality of the transceiver can be configured by using the appropriate signal level on the STS-12/STS-3 pin. STS-3/STM-1 mode is selected by pulling STS-12/STS-3 "Low" as described in the Hardware Pin Descriptions. However, if STS-12/STM-4 mode is desired, it is selected by pulling STS-12/STS-3 "High." Therefore, the following sections describe the functionality rather than how each function is controlled. Hence, the hardware Pin and the Register Bit Descriptions focus on device configuration. 1.2 Clock Input Reference for Clock Multiplier (Synthesizer) Unit The XRT91L32 can accept both a 19.44 MHz or a 77.76 MHz Differential LVPECL clock input at REFCLKP/N or a Single-Ended LVTTL clock at TTLREFCLK as its internal timing reference for generating higher speed clocks. The REFCLKP/N or TTLREFCLK input should be generated from an LVPECL/LVTTL crystal oscillator which has a frequency accuracy better than 20ppm in order for the transmitted data rate frequency to have the necessary accuracy required for SONET systems. The reference clock can be provided with one of two frequencies chosen by CMUFREQSEL. The reference frequency options for the XRT91L32 are listed in Table 1. TABLE 1: CMU REFERENCE FREQUENCY OPTIONS (DIFFERENTIAL OR SINGLE-ENDED) REFCLKP/N OR TTLREFCLK CMUFREQSEL STS12/STS3 0 0 77.76 MHz STS-3/STM-1 155.52 Mbps 0 1 77.76 MHz STS-12/STM-4 622.08 Mbps 1 0 19.44 MHz STS-3/STM-1 155.52 Mbps 1 1 19.44 MHz STS-12/STM-4 622.08 Mbps 1.3 REFERENCE FREQUENCY DATA RATE Data Latency Due to different operating modes and data logic paths through the device, there is an associated latency from data ingress to data egress. Table 2 specifies the data latency for a typical path. TABLE 2: DATA INGRESS TO DATA EGRESS LATENCY MODE OF OPERATION Thru-mode DATA PATH CLOCK REFERENCE RANGE OF CLOCK CYCLES MSB at RXIP/N to data on RXDO[7:0] Serial Remote Loopback MSB at RXIP/N to MSB at TXOP/N 11 Recoved RXIP/N Clock 25 to 35 Recoved RXIP/N Clock 2 to 4 XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER xr REV. 1.0.2 2.0 RECEIVE SECTION The receive section of XRT91L32 include the inputs RXIP/N, followed by the clock and data recovery unit (CDR) and receive serial-to-parallel converter. The receiver accepts the high speed Non-Return to Zero (NRZ) serial data at 622.08 Mbps or 155.52 Mbps through the input interfaces RXIP/N. The clock and data recovery unit recovers the high-speed receive clock from the incoming scrambled NRZ data stream. The recovered serial data is converted into an 8-bit-wide, 77.76 Mbps or 19.44 Mbps parallel data and presented to the RXDO[7:0] parallel interface. This parallel interface is designed for Single-Ended LVTTL operation. A divideby-8 version of the high-speed recovered clock RXPCLKOP/N, is used to synchronize the transfer of the 8-bit RXDO[7:0] data with the receive portion of the framer/mapper device. Upon initialization or loss of signal or loss of lock, the external reference clock signal of 19.44 MHz or 77.76 MHz is used to start-up the clock recovery phase-locked loop for proper operation. In certain applications, the CDR block on the XRT91L32 can be disabled and bypassed by enabling the CDRDIS pin to permit the flexibility of using an externally recovered receive clock thru the XRXCLKIP/N pins.7 2.1 Receive Serial Input The receive serial inputs are applied to RXIP/N. The receive serial inputs can be AC or DC coupled to an optical module or an electrical interface. A simplified AC coupling block diagram is shown in Figure 3.(Also, FIGURE 3. RECEIVE SERIAL INPUT INTERFACE BLOCK Install terminators close to RXIP and RXIN pins 82 Ohm RXIP SFP, Optical Module RXIN XRT91L32 STS-12/STM-4 or STS-3/STM-1 Transceiver Optical Fiber 1KOhm Tie unused differential input pins to VCC and GND XRXCLKIP XRXCLKIN Internally AC coupled 130 Ohm 1KOhm (optional) refer to application note TAN-9132.) NOTE: Some optical modules integrate AC coupling capacitors within the module. AC or DC coupling is largely specific to system design and optical module of choice. 12 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.2 2.2 Recieve Serial Data Input Timing The received High-Speed Serial Differential Data Input must adhere to the set-up and hold time timing specifications below. FIGURE 4. RECEIVE HIGH-SPEED SERIAL DATA INPUT TIMING DIAGRAM tRXCLK XRXCLKIP XRXCLKIN tRX_HD tRX_SU RXIP RXIN TABLE 3: RECEIVE HIGH-SPEED SERIAL DATA INPUT TIMING (STS-12/STM-4 OPERATION) SYMBOL PARAMETER MIN TYP MAX 1.608 UNITS tRXCLK Receive external recovered clock period ns tRX_SU Serial data setup time with respect to XRXCLKIP/N 400 ps tRX_HD Serial data hold time with respect to XRXCLKIP/N 100 ps TABLE 4: RECEIVE HIGH-SPEED SERIAL DATA INPUT TIMING (STS-3/STM-1 OPERATION) SYMBOL PARAMETER MIN TYP UNITS tRXCLK Receive external recovered clock period tRX_SU Serial data setup time with respect to XRXCLKIP/N 1.5 ns tRX_HD Serial data hold time with respect to XRXCLKIP/N 1.5 ns 13 6.43 MAX ns xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER 2.3 REV. 1.0.2 Receive Clock and Data Recovery The clock and data recovery (CDR) unit accepts the high speed NRZ serial data from the Differential LVPECL receiver and generates a clock that is the same frequency as the incoming data. The clock recovery can either utilize the transmitter's CMU reference clock from either REFCLKP/N or TTLREFCLK or it can use independent clock source CDRAUXREFCLK to train and monitor its clock recovery PLL. Initially upon startup, the PLL locks to the local reference clock within 500 ppm. Once this is achieved, the PLL then attempts to lock onto the incoming receive data stream. Whenever the recovered clock frequency deviates from the local reference clock frequency by more than approximately 500 ppm, the clock recovery PLL will switch and lock back onto the local reference clock. Whenever a Loss of Lock or a Loss of Signal event occurs, the CDR will continue to supply a receive clock (based on the local reference) to the framer/mapper device. When the LOSEXT is asserted by the optical module or when LOS is detected, the receive parallel data output will be forced to a logic zero state for the entire duration that a LOS condition is detected. This acts as a receive data mute upon LOS function to prevent random noise from being misinterpreted as valid incoming data. When the LOSEXT becomes inactive and the recovered clock is determined to be within 500 ppm accuracy with respect to the local reference source and LOS is no longer declared, the clock recovery PLL will switch and lock back onto the incoming receive data stream. Table 5 shows Clock and Data Recovery reference clock settings. Table 6 specifies the Clock and Data Recovery Unit performance characteristics. TABLE 5: CLOCK DATA RECOVERY UNIT REFERENCE CLOCK SETTINGS CMUFREQSEL CDRREFSEL STS12/ STS3 REFCLKP/N1OR TTLREFCLK1 FREQUENCY (MHZ) CDRAUXREFCLK2 FREQUENCY (MHZ) CDR OUTPUT FREQUENCY (MHZ) 0 0 0 77.76 MHz not used 155.52 0 0 1 77.76 MHz not used 622.08 1 0 0 19.44 MHz not used 155.52 1 0 1 19.44 MHz not used 622.08 X 1 0 not referenced by CDR 77.76 MHz 155.52 X 1 1 not referenced by CDR 77.76 MHz 622.08 1 Requires frequency accuracy better than 20ppm in order for the transmitted data rate frequency to have the necessary accuracy required for SONET systems. 2 CDRAUXREFCLK requires accuracy of 77.76 MHz +/- 500ppm. 14 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.2 TABLE 6: CLOCK AND DATA RECOVERY UNIT PERFORMANCE NAME PARAMETER MIN TYP 40 MAX UNITS 60 % REFDUTY Reference clock duty cycle REFJIT Reference clock jitter (rms) with 19.44 MHz reference1 5 ps REFJIT Reference clock jitter (rms) with 77.76 MHz reference1 13 ps REFTOL Reference clock frequency tolerance2 -20 +20 ppm TOLJIT Input jitter tolerance with 1 MHz < f < 20 MHz PRBS pattern 0.3 OCLKFREQ Frequency output 620 624 MHz OCLKDUTY Clock output duty cycle 40 60 % 0.4 UI Jitter specification is defined using a 12kHz to 1.3/5MHz LP-HP single-pole filter. 1 These reference clock jitter limits are required for the outputs to meet SONET system level jitter requirements (<10 mUIrms). 2 Required to meet SONET output frequency stability requirements. 2.3.1 Internal Clock and Data Recovery Bypass Optionally, the internal CDR unit can be disabled and bypassed in lieu of an externally recovered clock. Asserting the CDRDIS "High" disables the internal Clock and Data Recovery unit and the received serial data bypasses the integrated CDR block. RXINP/N is then sampled on the rising edge of the externally recovered differential clock XRXCLKIP/N coming from the optical module or an external clock recovery unit. Figure 5 shows the possible internal paths of the recovered clock and data. CLOCK MUX FIGURE 5. INTERNAL CLOCK AND DATA RECOVERY BYPASS XRXCLKIP XRXCLKIN Clk CDRDIS CDR SIPO DATA MUX Data Div by 8 CLOCK Parallel DATA 8 15 RXIP RXIN xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER 2.4 REV. 1.0.2 External Receive Loop Filter Capacitors These external loop filter 0.47F non-polarized capacitors provide the necessary components to achieve the required receiver jitter performance. They must be well isolated to prohibit noise entering the CDR block and should be placed as close to the pins as much as possible. Figure 6 shows the pin connections and external loop filter components. These two non-polarized capacitors should be of +/- 10% tolerance. FIGURE 6. EXTERNAL LOOP FILTERS 0.47uF 0.47uF non-polarized non-polarized Pin 63 Pin 66 CAP1P 2.5 Pin 64 CAP2P CAP1N Pin 65 CAP2N Loss Of Signal XRT91L32 supports internal Loss of Signal detection (LOS) and external LOS detection. The internal Loss of Signal Detector monitors the incoming data stream and if the incoming data stream has no transition continuously for more than 128 bit periods, Loss of Signal is declared. This LOS detection will be removed when the circuit detects 16 transitions in a 128 bit period sliding window. Pulling the corresponding DLOSDIS signal to a high level will disable the internal LOS detection circuit. The external LOS function is supported by the LOSEXT input. The Single-Ended LVPECL input usually comes from the optical module through an output usually called "SD" or "FLAG" which indicates the lack or presence of optical power. Depending on the manufacturer of these devices the polarity of this signal can be either active "Low" or active "High." LOSEXT is an active "Low" signal requiring a low level to assert or invoke a forced LOS. The external LOSEXT input pin and internal LOS detector are gated to control detection and declaration of Loss of Signal (see Figure 7.) Whenever LOS is internally detected or an external LOS is asserted thru the LOSEXT pin, the XRT91L32 will automatically force the receive parallel data output to a logic state "0" for the entire duration that a LOS condition is declared. This acts as a receive data mute upon LOS function to prevent random noise from being misinterpreted as valid incoming data. FIGURE 7. LOS DECLARATION CIRCUIT Internal LO S D etect LO S D eclaration D LO SD IS LO S E X T ( S D ) 16 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.2 2.6 SONET Frame Boundary Detection and Byte Alignment Recovery A Frame and Byte Boundary Detection circuit searches the incoming data channel for three consecutive A1 (0xF6 Hex) bytes followed by three consecutive A2 (0x28 Hex) bytes. The detector operates under the control of the OOF (Out of Frame) signals provided from the SONET Framer. Detection is enabled when OOF is held "High" and remains active until OOF goes "Low." When framing pattern detection is enabled, the framing pattern is used to locate byte and frame boundaries in the incoming receive data stream. The receive serial-toparallel converter block uses the located byte boundary to assemble the incoming data stream into bytes for output on the parallel data output bus RXDO[7:0]. The frame boundary is reported on the frame pulse (FRAMEPULSE) output at the onset of detecting the third A2 byte pattern when any serial 48-bit pattern matching the framing pattern is detected on the incoming data stream. While in the pattern search and detection state and so long is OOF is active, the frame pulse (FRAMEPULSE) output is activated for one byte clock cycle (RXPCLKO = 12.86 ns pulse duration for STS-12/STM-4 or 51.44 ns pulse duration for STS-3/ STM-1) anytime a 48-bit pattern matching the framing pattern is detected on the incoming data stream. Once the SONET Framer Overhead Circuitry has verified that frame and byte synchronization are correct, the OOF input pin should be de-asserted by the SONET Framer to disable the XRT91L32 frame search process from trying to synchronize repeatedly and to de-activate FRAMEPULSE. When the XRT91L32's framing pattern detection is disabled upon the de-assertion of OOF input pin from the SONET Framer, the byte boundary will lock to the detected location and will remain locked to that location found when detection was previously enabled. 2.7 Receive Serial Input to Parallel Output (SIPO) During STS-12/STM-4 operation, the SIPO is used to convert the 622.08 Mbps serial data input to 77.76 Mbps parallel data output which can interface to a SONET Framer/ASIC. If the XRT91L32 is operating in STS-3/ STM-1, the SIPO will convert the 155.52 Mbps serial data input to 19.44 Mbps parallel data output. The SIPO bit de-interleaves the serial data input into an 8-bit parallel output to RXDO[7:0]. A simplified block diagram is shown in Figure 8. XRT91L32 clocks data out on RXDO[7:0] at the falling edge of RXPCLKO. FIGURE 8. SIMPLIFIED BLOCK DIAGRAM OF SIPO 8-bit Parallel LVTTL Output Data b03 b02 b01 b00 RXDOn bn3 bn2 bn1 bn0 RXDOn+ bn+3 bn+2 bn+1 bn+0 RXDO7 b73 b72 b71 b70 RXPCLKO 622.08 Mbps STS-12/STM-4 or 155.52 Mbps STS-3/STM-1 serial data rate SIPO RXDO0 b73 b63 b53 b43 b33 b23 b13 77.76 MHz (STS-12/STM-4) or 19.44 MHz (STS-3/STM-1) 17 b70 b60 b50 b40 b30 b20 b10 b00 RXIP/N xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER 2.8 REV. 1.0.2 Receive Parallel Output Interface The 8-bit Single-Ended LVTTL running at 77.76 Mbps (STS-12/STM-4) or 19.44 Mbps (STS-3/STM-1) parallel data output of the receive path is used to interface to a SONET Framer/ASIC synchronized to the recovered clock. A simplified block diagram is shown in Figure 9. FIGURE 9. RECEIVE PARALLEL OUTPUT INTERFACE BLOCK RXDO[7:0] 8 RXPCLKO XRT91L32 STS-12/STM-4 or STS-3/STM-1 Transceiver SONET Framer/ASIC 2.9 Disable Parallel Receive Data Output Upon LOS The parallel receiver outputs are automatically pulled "Low" or forced to a logic state of "0" during a LOS condition to prevent data chattering unless LOS detection is disabled by asserting DLOSDIS and keeping LOSEXT input pin "high." In addition, the user can also assert LOSEXT input pin "low" from the optical module to force an LOS and mute the parallel receiver outputs as well (while DLOSDIS input is also low, see Figure 7.) 18 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.2 2.10 Receive Parallel Data Output Timing The receive parallel data output from the STS-12/STM-4 or STS-3/STM-1 receiver will adhere to the setup and hold times shown in Figure 10 ,Table 7, and Table 8. Table 9 shows the PECL and TTL output timing specifications. FIGURE 10. RECEIVE PARALLEL OUTPUT TIMING tRXCLK RXIP RXIN tRXPCLKO RXPCLKO RXDO[7:0] A1 A2 A2 A2 A2 tRXDO_VALID FRAMEPULSE tPULSE_WID TABLE 7: RECEIVE PARALLEL DATA OUTPUT TIMING (STS-12/STM-4 OPERATION) SYMBOL tRXCLK tRXPCLKO PARAMETER MIN TYP MAX UNITS Receive high-speed serial clock period 1.608 ns Receive parallel data output byte clock period 12.86 ns tRXDO_VALID Time the data is valid on RXDO[7:0] and FRAMEPULSE before and after the rising edge of RXPCLKO tPULSE_WID Pulse width of frame detection pulse on FRAMEPULSE 4 ns 12.86 ns TABLE 8: RECEIVE PARALLEL DATA OUTPUT TIMING (STS-3/STM-1 OPERATION) SYMBOL tRXCLK tRXPCLKO PARAMETER MIN TYP MAX UNITS Receive high-speed serial clock period 6.43 ns Receive parallel data output byte clock period 51.44 ns tRXDO_VALID Time the data is valid on RXDO[7:0] and FRAMEPULSE before and after the rising edge of RXPCLKO tPULSE_WID Pulse width of frame detection pulse on FRAMEPULSE 19 22 ns 51.44 ns xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.2 TABLE 9: PECL AND TTL RECEIVE OUTPUTS TIMING SPECIFICATION SYMBOL PARAMETER tR_PECL PECL output rise time (20% to 80%) 350 ps tF_PECL PECL output fall time (80% to 20%) 350 ps tR_TTL TTL output rise time (10% to 90%) 2 ns tF_TTL TTL output fall time (90% to 10%) 1.5 ns 20 MIN TYP MAX UNITS xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 3.0 TRANSMIT SECTION The transmit section of the XRT91L32 accepts 8-bit parallel data and converts it to serial Differential LVPECL data output intented to interface to an optical module. It consists of an 8-bit parallel Single-Ended LVTTL interface, Parallel-to-Serial Converter, a clock multiplier unit (CMU), a Low Voltage Positive-referenced EmitterCoupled Logic (LVPECL) differential line driver, and Loop Timing modes. The LVPECL serial data output rate is 622.08 Mbps for STS-12/STM-4 applications and 155.52 Mbps for STS-3/STM-1 applications. The high frequency serial clock is synthesized by a PLL, which uses a low frequency clock as its input reference. In order to synchronize the data transfer process, the synthesized 622.08 MHz for STS-12/STM-4 or 155.52 MHz STS-3/STM-1 serial clock output is divided by eight and the 77.76 MHz (STS-12/STM-4) or 19.44 MHz (STS-3/ STM-1) clock respectively is presented to the framer/mapper device to be used as its timing source. 3.1 Transmit Parallel Input Interface The parallel data from an framer/mapper device is presented to the XRT91L32 through an 8-bit Single-Ended LVTTL parallel bus interface TXDI[7:0]. To directly interface to the XRT91L32, the SONET Framer/ASIC must be synchronized to the same timing source TXPCLK_IO in presenting data on the parallel bus interface. The data must meet setup and hold times with respect to TXPCLK_IO. This clock output source is used to synchronize the SONET Framer/ASIC to the XRT91L32. The framer/mapper device should use TXPCLK_IO as its timing source so that parallel data is phase aligned with the serial transmit data. The data is latched into a parallel input register on the rising edge of TXPCLK_IO. TXPCLK_IO is derived from a divide-by-8 of the high speed synthesized clock resulting in a 77.76/ 19.44 MHz Single-Ended LVTTL clock output source to be used by the framer/mapper device for parallel bus synchronization. A simplified block diagram of the transmit parallel bus clock output system interface is shown in Figure 11. FIGURE 11. TRANSMIT PARALLEL INPUT INTERFACE BLOCK TXDI[7:0] 8 TXPCLK_IO XRT91L32 STS-12/STM-4 or STS-3/STM-1 Transceiver SONET Framer/ASIC CMUREFSEL REFCLKN REFCLKP TTLREFCLK 21 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER 3.2 REV. 1.0.3 Transmit Parallel Data Input Timing When applying parallel data input to the transmitter, the setup and hold times should be followed as shown in Figure 12 and Table 10, Table 11. FIGURE 12. TRANSMIT PARALLEL INPUT TIMING Transmit Parallel Clock driven by XRT91L32 Device Transmit Parallel Clock Output tTXPCLK_IO TXPCLK_IO tTXDI_HD tTXDI_SU TXDI[7:0] TABLE 10: TRANSMIT PARALLEL DATA INPUT TIMING (STS-12/STM-4 OPERATION) SYMBOL tTXPCLK_IO PARAMETER MIN Transmit Clock Output period TYP MAX 12.86 UNITS ns tTXDI_SU Transmit data setup time with respect to TXPCLK_IO 1.0 ns tTXDI_HD Transmit data hold time with respect to TXPCLK_IO1 1.0 ns TABLE 11: TRANSMIT PARALLEL DATA INPUT TIMING (STS-3/STM-1 OPERATION). SYMBOL tTXPCLK_IO PARAMETER MIN Transmit Clock Output period TYP 51.44 MAX UNITS ns tTXDI_SU Transmit data setup time with respect to TXPCLK_IO 1.0 ns tTXDI_HD Transmit data hold time with respect to TXPCLK_IO1 1.0 ns 22 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 3.3 Transmit Parallel Input to Serial Output (PISO) The PISO is used to convert 77.76 Mbps or 19.44 Mbps parallel data input to 622.08 Mbps STS-12/STM-1 or 155.52 Mbps STS-3/STM-1 serial data output respectively, which can interface to an optical module. The PISO bit interleaves parallel data input into a serial bit stream taking the first bit from TXDI7, then the first bit from TXDI6, and so on as shown in Figure 13. FIGURE 13. SIMPLIFIED BLOCK DIAGRAM OF PISO 8-bit Parallel LVTTL Input Data TXDI0 b07 b06 b05 b04 b03 b02 b01 b00 TXDIn bn7 bn6 bn5 bn4 bn3 bn2 bn1 bn0 PISO time (0) 622.08 Mbps STS-12/STM-4 or 155.52 Mbps STS-3/STM-1 serial data rate b77 b67 b57 b47 b37 b27 b17 b07 b70 b60 b50 b40 b30 b20 b10 b00 TXOP/N TXDIn+ bn+7 bn+6 bn+5 bn+4 bn+3 bn+2 bn+1 bn+0 TXDI7 b77 b76 b75 b74 b73 b72 b71 b70 TXPCLK_IO 3.4 77.76 MHz (STS-12/STM-4) or 19.44 MHz (STS-3/STM-1) Clock Multiplier Unit (CMU) and Re-Timer The clock synthesizer uses a 77.76 MHz or a 19.44 MHz reference clock to generate the 622.08 MHz (for STS12/STM-4) or 155.52 MHz (for STS-3/STM-1) SONET/SDH transmit serial data rate frequency. Differential LVPECL input REFCLKP/N accepts a clock reference of 77.76 MHz or 19.44 MHz to synthesize a high speed 622.08 MHz clock for STS-12/STM-4 or 155.52 MHz clock for STS-3/STM-1 applications. Optionally, if a Differential LVPECL clock source is not available, TTLREFCLK can accept an LVTTL clock signal. The clock synthesizer uses a PLL to lock-on to the differential input REFCLKP/N or Single-Ended input TTLREFCLK reference clock. The REFCLKP/N input should be generated from an LVPECL crystal oscillator which has a frequency accuracy better than 20ppm in order for the transmitted data rate frequency to have the necessary accuracy required for SONET systems. If the TTLREFCLK reference clock is used, the TTLREFCLK reference input should be tied to a LVTTL crystal oscillator with 20ppm accuracy. The two reference clocks are XNOR'ed and the choice between the LVPECL and LVTTL clocks are controlled tying either REFCLKP or TTLREFCLK to ground. Table 1, on page 11 shows the CMU reference clock frequency settings. Table 12 specifies the Clock Multiplier Unit's requirements for the reference clock. TABLE 12: CLOCK MULTIPLIER UNIT REQUIREMETNS FOR REFERENCE CLOCK NAME PARAMETER MIN TYP 40 MAX UNITS 60 % REFDUTY Reference clock duty cycle REFJIT Reference clock jitter (rms) with 19.44 MHz reference1 5 ps REFJIT Reference clock jitter (rms) with 77.76 MHz reference1 13 ps REFTOL Reference clock frequency tolerance2 +20 ppm ECLKJIT STS-3/STM-1 Electrical Clock output jitter (rms) with 19.44 MHz reference 1 mUIrms ECLKJIT STS-12/STM-4 Electrical Clock output jitter (rms) with 19.44 MHz reference 5 mUIrms ECLKJIT STS-3/STM-1 Electrical Clock output jitter (rms) with 77.76 MHz reference 2 mUIrms -20 23 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER NAME REV. 1.0.3 PARAMETER MIN ECLKJIT STS-12/STM-4 Electrical Clock output jitter (rms) with 77.76 MHz reference OCLKFREQ Frequency output OCYCDUTY Clock output duty cycle ('1010' data pattern) TYP MAX 4 UNITS mUIrms 620 624 MHz 45 55 % Jitter specification is defined using a 12kHz to 1.3/5MHz LP-HP single-pole filter. 1These 2 3.5 reference clock jitter limits are required for the outputs to meet SONET system level jitter requirements (<10 mUIrms). Required to meet SONET output frequency stability requirements. Loop Timing and Clock Control Two types of loop timing are possible in the XRT91L32. In the internal loop timing mode, loop timing is controlled by the LOOPTIME pin. This mode is selected by asserting the LOOPTIME signal to a high level. When the loop timing mode is activated, the CMU synthesized hi-speed reference clock input to the Retimer is replaced with the hi-speed internally recovered receive clock coming from the CDR. Under this condition both the transmit and receive sections are synchronized to the internally recovered receive clock. Loop time mode directly locks the Retimer to the recovered receive clock. In external loop timing mode, the XRT91L32 allows the user the flexibility of using an externally recovered receive clock for retiming the high speed serial data. First, the CDRDIS input pin should be set high. By doing so, the internal CDR is disabled and bypassed and the XRT91L32 will sample the incoming high speed serial data on RXIP/N with the externally recovered receive clock connected to the XRXCLKIP/N inputs. In this state, the receive clock de-jittering and recovery is done externally and fed thru XRXCLKIP/N and the XRT91L32 will sample RXIP/N on the rising edge of XRXCLKIP/N. Secondly, the LOOPTIME pin must also be set high in order to select the externally recovered receive clock on XRXCLKIP/N as the reference clock source for the transmit serial data output stream TXOP/N. Table 13 provides configuration for selecting the loop timing and clock recovery modes. The use of the on-chip CDR or an external recovered clock in loop timing applications is shown in Figure 14. TABLE 13: LOOP TIMING AND CLOCK RECOVERY CONFIGURATIONS CDRDIS LOOPTIME TRANSMIT CLOCK SOURCE RECEIVE CLOCK SOURCE 0 0 Clock Multiplier Unit CDR Enabled. Clock and Data recovery by internal CDR 0 1 Internal CDR CDR Enabled. Clock and Data recovery by internal CDR Clock Multiplier Unit CDR Disabled. Externally recovered Receive Clock from XRXCLKIP/N 622.08/155.52 Mbps data on RXIP/N sampled at rising edge of XRXCLKIP/N External CDR thru XRXCLKIP/N CDR Disabled. Externally recovered Receive Clock from XRXCLKIP/N 622.08/155.52 Mbps data on RXIP/N sampled at rising edge of XRXCLKIP/N 1 1 0 1 24 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 FIGURE 14. LOOP TIMING MODE USING INTERNAL CDR OR AN EXTERNAL RECOVERED CLOCK XRT91L32 REFCLKP REFCLKN 622.08/ 155.52MHz CMU TTLREFCLK MUX DATA TXDI[7:0] PISO 8 TXPCLK_IO CLK 0 1 to Retimer MUX ENB TXOP TXON Retimer Div by 8 ENB VDD MUX LOOPTIME CDRDIS CLK XRXCLKIP XRXCLKIN Clk RXIP RXIN CDR RXDO[7:0] ~ RXPCLKO 3.6 8 SIPO DATA MUX Data ~ Div by 8 Transmit Serial Output Control The 622.08 Mbps STS-12/STM-4 or 155.52 Mbps STS-3/STM-1 transmit serial output is avaliable on TXOP/N pins. The transmit serial output can be AC or DC coupled to an optical module or electrical interface. A simplified block diagram with internally AC-coupled SFP is shown in Figure 15. Also, refer to application note FIGURE 15. TRANSMIT SERIAL OUTPUT INTERFACE BLOCK TXOP SFP, Optical Module TXON XRT91L32 STS-12/STM-4 or STS-3/STM-1 Transceiver Optical Fiber 187 Ohm Internally AC coupled and terminated into 100 Ohm Install close to 91L30 TAN-9132.) NOTE: Some optical modules integrate AC coupling capacitors within the module. AC or DC coupling is largely specific to system design and optical module of choice. 25 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 4.0 DIAGNOSTIC FEATURES 4.1 Serial Remote Loopback The serial remote loopback function is activated by setting RLOOPS "High". When serial remote loopback is activated, the high-speed serial receive data from RXIP/N is presented at the high speed transmit output TXOP/N, and the high-speed recovered clock is selected and presented to the high-speed transmit clock input of the Retimer. During serial remote loopback, the high-speed receive data (RXIP/N) is also converted to parallel data and presented at the low-speed receive parallel interface RXDO[7:0]. The recovered receive clock is also divided by 8 and presented at the low-speed clock output RXPCLKO to synchronize the transfer of the 8-bit received parallel data. A simplified block diagram of serial remote loopback is shown in Figure 16. FIGURE 16. SERIAL REMOTE LOOPBACK Serial Rem ote Loopback PISO Re-Timer SIPO CD R LVPECL O utput Drivers R x Parallel O utput 4.2 LVPECL Input Drivers Tx Serial O utput Rx Serial Input Digital Local Loopback The digital local loopback is activated when the DLOOP signal is set "High." When digital local loopback is activated, the high-speed data from the output of the parallel to serial converter is looped back and presented to the high-speed input of the receiver serial to parallel converter. The CMU output is also looped back to the receive section and is used to synchronize the transfer of the data through the receiver. In Digital loopback mode, the transmit data from the transmit parallel interface TXDI[7:0] is serialized and presented to the highspeed transmit output TXOP/N using the high-speed 622.08/155.52 MHz transmit clock generated from the clock multiplier unit and presented to the input of the Retimer and SIPO. A simplified block diagram of digital loopback is shown in Figure 17. Receive Data mute upon LOS, as shown in Figure 7, applies to Digital Local FIGURE 17. DIGITAL LOCAL LOOPBACK Digital Loopback Tx Parallel Input PISO Re-Timer SIPO CDR LVPECL Output Drivers Rx Parallel Output Loopback Mode 26 LVPECL Input Drivers Tx Serial Output xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 4.3 Analog Local Loopback Analog Local Loopback (ALOOP) controls a more comprehensive version of digital local loopback in which the point where the transmit data is looped back is moved all the way back to the high-speed receive I/O. The transmit data from the transmit parallel interface TXDI[7:0] is serialized and presented to the high-speed transmit output TXOP/N using the high-speed 622.08/155.52 MHz transmit clock generated from the clock multiplier unit. In addition, the high-speed transmit data TXOP/N is looped back to the receive clock and data recovery unit, replacing the RXIP/N. The signal is then processed by the CDR, and is sent through the serial to parallel converter and presented at the low-speed receive parallel interface RXDO[7:0]. ALOOP is invoked by asserting the ALOOP pin "High." A simplified block diagram of parallel remote loopback is shown in Figure 18. Receive data mute upon "LOS FIGURE 18. ANALOG LOCAL LOOPBACK Analog Local Loop back Tx Parallel Input PISO LVPECL Output Drivers Re-Timer Tx Serial Output Rx Parallel Output SIPO 4.4 CDR LVPECL Input Drivers Split Loopback The serial remote loopback and the digital local loopback can be combined to form a split loopback. The output of the parallel to serial converter is looped back and presented to the high-speed input of the receiver serial to parallel converter. The high-speed serial receive data from RXIP/N is presented at the high speed transmit output TXOP/N, and the high-speed recovered clock is selected to re-time the high speed transmit data output. A simplified block diagram of parallel remote loopback is shown in Figure 19. FIGURE 19. SPLIT LOOPBACK Split Loopback Tx Parallel Input PISO Re-Timer LVPECL Output Drivers SIPO CDR LVPECL Input Drivers Rx Parallel Output 27 Tx Serial Output Rx Serial Input XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER 4.5 Eye Diagram The XRT91L32 Eye diagram illustrates the transmit serial output signal integrity and quality. FIGURE 20. STS-3/STM-1 EYE DIAGRAM FIGURE 21. STS-12/STM-4 EYE DIAGRAM 28 xr REV. 1.0.3 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 4.6 SONET Jitter Requirements SONET equipment jitter requirements are specified for the following three types of jitter. The definitions of each of these types of jitter are given below. SONET equipment jitter requirements are specified for the following three types of jitter. 4.6.1 Jitter Tolerance: Jitter tolerance is defined as the peak-to-peak amplitude of sinusoidal jitter applied on the input OC-N equipment interface that causes an equivalent 1dB optical power penalty. OC-1/STS-1, OC-3/STS-3, OC-12 and OC-48 category II SONET interfaces should tolerate, the input jitter applied according to the mask of Figure 22, with the corresponding parameters specified in the figure. FIGURE 22. JITTER TOLERANCE MASK A3 slope= -20dB/decade Input Jitter Amplitude (UIpp) A2 slope= -20dB/decade A1 f0 f1 f2 f4 f3 Jitter Frequency (Hz) OC-N/STS-N LEVEL F0 (HZ) F1 (HZ) F2 (HZ) F3 (HZ) F4 (HZ) A1 (UIPP) A2 (UIPP) A3 (UIPP) 1 10 30 300 2K 20K 0.15 1.5 15 3 10 30 300 6.5K 65K 0.15 1.5 15 12 10 30 300 25K 250K 0.15 1.5 15 48 10 600 6000 100K 1000K 0.15 1.5 15 29 XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER FIGURE 23. XRT91L32 MEASURED JITTER TOLERANCE AT 622.08 MBPS STS-12/STM-4 FIGURE 24. XRT91L32 MEASURED JITTER TOLERANCE AT 155.52 MBPS STS-3/STM-1 30 xr REV. 1.0.3 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 4.6.2 Jitter Generation Jitter generation is defined as the amount of jitter at the STS-N output in the absence of applied input jitter. The Bellcore and ITU requirement for this type jitter is 0.01UI rms measured with a specific band-pass filter. For more information on these specifications refer to Bellcore TR-NWT-000253 sections 5.6.2-5 and GR-253CORE section 5.6. Phase noise plot shows the power of the noise with respect to the carrier power. When this curve is integrated in the frequency band of interest, the outcome is the noise power. Jitter generation in rms is then derived by factoring with the appropriate period for the clock cycle. FIGURE 25. XRT91L32 MEASURED ELECTRICAL PHASE NOISE TRANSMIT JITTER GENERATION AT 622.08 MBPS STS-12/STM4 USING '1010' OUTPUT PATTERN Phase Noise Transmit Jitter Generation (Wide Band) using HP8560E -90 -95 dBC/Hz -100 -105 -110 -115 -120 1 10 100 1000 Frequency (kHz) REFCLK = 19.44 MHz 31 10000 100000 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 5.0 ELECTRICAL CHARACTERISTICS ABSOLUTE MAXIMUM RATINGS Thermal Resistance of QFP Package........jA = 45C/W Operating Temperature Range.................-40C to 85C Thermal Resistance of QFP Package........jC = 12C/W Case Temperature under bias..................-55C to 125C ESD Protection (HBM)..........................................>2000V Storage Temperature ...............................-65C to 150C ABSOLUTE MAXIMUM POWER AND INPUT/OUTPUT RATINGS SYMBOL TYPE VDD3.3 PARAMETER MIN. TYP. MAX. UNITS CMOS Digital Power Supply -0.5 6.0 V PECL I/O Power Supply -0.5 6.0 V 3.3V Analog I/O and Power Supply -0.5 6.0 V LVPECL DC logic signal input voltage -0.5 VDDLVPECL +0.5 V LVTTL DC logic signal input voltage -0.5 5.5 V LVTTL DC logic signal output voltage -0.5 VDD3.3 +0.5 V LVPECL Input current -100 100 mA LVTTL Input current -100 100 mA VDDLVPECL AVDD_IO NOTE: Stresses listed under Absolute Maximum Power and I/O ratings may be applied to devices one at a time without causing permanent damage. Functionality at or above the values listed is not implied. Exposure to these values for extended periods will severely affect device reliability. POWER AND CURRENT DC ELECTRICAL CHARACTERISTICS Test Conditions: TA = 25C, VDD = 3.3V + 5% unless otherwise specified SYMBOL TYPE PARAMETER MIN. TYP. MAX. UNITS VDD3.3 Power Supply Voltage 3.135 3.3 3.465 V AVDD3.3 Transmit Power Supply Voltage (AVDD3.3_TX) 3.135 3.3 3.465 V AVDD3.3 Receiver Power Supply Voltage (AVDD3.3_RX) 3.135 3.3 3.465 V PECL I/O Power Supply Voltage 3.135 3.3 3.465 V VDD LVPECL IDD-OC3 Total Power Supply Current 200 mA IDD-OC12 Total Power Supply Current 242 mA PDD-OC3 Total Power Consumption 660 mW PDD-OC12 Total Power Consumption 800 mW 32 CONDITIONS xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 LVPECL AND LVTTL LOGIC SIGNAL DC ELECTRICAL CHARACTERISTICS Test Conditions: TA = 25C, VDD = 3.3V + 5% unless otherwise specified SYMBOL TYPE PARAMETER VOH LVPECL Output High Voltage VOL LVPECL Output Low Voltage 0.7 VOCOMM LVPECL Output Common Mode Voltage 1.1 VDDLVPECL - 1.3 V VODIFF LVPECL Output Differential Voltage 600 1300 mV Terminate with 50 to VDDLVPECL- 2.0 VIH LVPECL Input High Voltage VDDLVPECL - 0.9 VDDLVPECL - 0.3 V For Single-Ended VIL LVPECL Input Low Voltage 0 VDDLVPECL - 1.72 V For Single-Ended VIDIFF LVPECL Input PECL Differential Voltage 400 1600 mV VICOMM LVPECL Input PECL Common Mode Voltage VOH LVTTL Output High Voltage MIN TYP MAX UNITS VDDLVPECL - 0.9 V CONDITIONS V 2.0 V 2.0 V IOH = -18.0mA at VOH=2.4V VOL LVTTL Output Low Voltage 0 0.8 V IOL = 15.0mA at VOL=0.4V VIH LVTTL Input High Voltage 2.0 VIL LVTTL Input Low Voltage 0 IIH LVTTL Input High Current V 50 0.8 V 500 A 2.0V<VIN<5.5V VIN=2.4V typical IIL LVTTL Input Low Current -500 33 A -0.5V<VIN<0.8V xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 ORDERING INFORMATION PART NUMBER PACKAGE OPERATING TEMPERATURE RANGE XRT91L32IQ-F 100-pin Plastic Quad Flat Pack (14.0 x 20.0 x 2.7 mm3, QFP) -40C to +85C PACKAGE DIMENSIONS (14 x 20 x 2.7mm, QFP, 1.6mm form) Rev. 1.00 D D1 51 80 50 81 E1 E 31 100 1 A2 30 e (Pin 1 feature is mfger option) B C A Seating Plane A1 SYMBOL A A1 A2 B C D D1 E E1 e L L 1.6mm form INCHES MILLIMETERS MIN MAX MIN MAX 0.102 0.134 2.60 3.40 0.010 0.020 0.25 0.50 0.100 0.120 2.55 3.05 0.009 0.015 0.22 0.38 0.005 0.009 0.13 0.23 0.904 0.923 22.95 23.45 0.783 0.791 19.90 20.10 0.667 0.687 16.95 17.45 0.547 0.555 13.90 14.10 0.0256 BSC 0.65 BSC 0.029 0.040 0.73 1.03 0 7 0 7 Note: The control dimension is the millimeter column 34 xr XRT91L32 STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER REV. 1.0.3 REVISION HISTORY REVISION # 1.0.0 DATE DESCRIPTION November 2006 XRT91L32 datasheet release version. 1.0.1 11/07/06 correct typo errors 1.0.2 11/08/06 Added Min Reset pulse width of 100nS in pin description, correct typo errors. 1.0.3 06/14/07 Corrected Figure 3 to portray an application with AC-coupled SFP Corrected the serial data bit order in Figure 13 Made pin 81 VDD only Minor editorial corrections NOTICE EXAR Corporation reserves the right to make changes to the products contained in this publication in order to improve design, performance or reliability. EXAR Corporation assumes no responsibility for the use of any circuits described herein, conveys no license under any patent or other right, and makes no representation that the circuits are free of patent infringement. Charts and schedules contained here in are only for illustration purposes and may vary depending upon a user's specific application. While the information in this publication has been carefully checked; no responsibility, however, is assumed for inaccuracies. EXAR Corporation does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless EXAR Corporation receives, in writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized; (b) the user assumes all such risks; (c) potential liability of EXAR Corporation is adequately protected under the circumstances. Copyright 2006 EXAR Corporation Datasheet November 2006. Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited. 35