SY58621L Precision 3.2Gbps CML/LVPECL Backplane Transceiver with Integrated Loopback General Description The SY58621L is a low jitter, high-speed transceiver with a variable swing LVPECL transmitter buffer and a CML high-gain receiver optimized for precision telecom and enterprise server transmission line and backplane data management. The SY58621L distributes data to 3.2Gbps guaranteed over temperature and voltage. The SY58621L transmitter differential input includes Micrel’s unique, patented 3-pin input termination architecture that directly interfaces to any (AC- or DCcoupled) differential signal as small as 100mV (200mVPP) without any termination resistor network in the signal path. The receiver differential input is optimized to interface directly to AC-coupled signals as small as 10mV (20mVPP). The receiver output is 50_ source-terminated CML and the transmitter output is variable swing 80mV to 800mV LVPECL with extremely fast rise/fall time. To support remote self-testing, the SY58621L features a high-speed loopback test mode. The input control signal LOOPBACK enables an internal loopback path from the transmitter input to the receiver output. The SY58621L operates from a 3.3V ±10% supply and is guaranteed over the full industrial temperature range of –40°C to +85°C. The SY58621L is part of Micrel’s ® high-speed, Precision Edge product line. For applications that requires a CML receiver and transmitter, consider the SY58620L. All support documentation can be found on Micrel’s web site at: www.micrel.com. Applications ∑ ∑ ∑ ∑ Backplane management Active cable transceivers SONET/SDH data/clock applications 4X Fibre Channel applications ® Precision Edge Features ∑ Guaranteed AC performance over temperature and voltage: - Maximum Throughput 3.2Gbps - <160ps tr/tf time ∑ Transmitter - Patented input termination directly interfaces to ACor DC-coupled differential inputs - Variable swing LVPECL output ∑ Receiver - 32dB high-gain Input - Internal 50Ω input termination - Accepts AC-coupled input signals as small as 10mV (20mvPP) - 400mV (800mVPP) differential CML output swing ∑ Loss-of-Signal (LOS) - High-gain, TTL-compatible LOS output with internal 4.75kΩ pull-up - Programmable LOS level set ∑ Ultra-low jitter design - <5psRMS random jitter ∑ Patent-pending MUX isolates the receiver and the transmitter channels minimizing on crosstalk ∑ Selectable loopback diagnostic mode ∑ Output enables on transmitter and receiver outputs ∑ Power supply +3.3V ±10% ∑ Industrial temperature range -40°C to +85°C ∑ Available in 24-pin (4mm x 4mm) QFN Markets ∑ ∑ ∑ ∑ Precision telecom Enterprise server ATE Test and measurement Precision Edge is a registered trademark of Micrel, Inc. Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com January 2006 M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L Typical Applications Functional Block Diagram Note: It is recommended that RLOSLVL ≤10kΩ. See the “Typical Operating Characteristics” section for more details. January 2006 2 M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L Ordering Information(1) Part Number Package Type Operating Range Package Marking Lead Finish SY58621LMG QFN-24 Industrial 621L with Pb-Free bar-line indicator NiPdAu Pb-Free QFN-24 Industrial 621L with Pb-Free bar-line indicator NiPdAu Pb-Free SY58621LMGTR (2) Notes: 1. Contact factory for die availability. Dice are guaranteed at TA = 25ºC, DC Electricals only. 2. Tape and Reel. Pin Configuration 24-Pin QFN January 2006 3 M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L Pin Description Inputs Pin Number Pin Name 23 LOOPBACK 20 /RXEN Receiver Output Control. TTL/CMOS control input. /RXEN is an active LOW signal used to enable the receiver outputs. /RXEN is internally connected to a 25kW pull-down resistor and will default to a LOW state if left open. VTH = VCC/2. 1, 2 RXIN, /RXIN Receiver Differential Input. Input accepts AC differential signals as small as 10mV (20mVPP). Each pin internally terminates to VCC_RXIN-1.3V (internal voltage reference) through 50W. Input will default to an indeterminate state if left open. See figure 6b. 7 /TXEN Transmitter Output Control. TTL/CMOS control input. /TXEN is an active LOW signal used to enable the transmitter output. /TXEN is internally connected to a 25kW pull-down resistor and will default to a LOW state if left open. VTH = VCC/2. 14, 13 TXIN, /TXIN Transmitter Differential Input. Input accepts AC- or DC-coupled differential signals as small as 100mV (200mVPP). Each pin terminates to the TXVT pin through 50W. Note that this input will default to an indeterminate state if left open. See figure 6a. 9 TXVCTRL Transmitter Output Swing Control. Input that controls the output amplitude of the transmitter. The operating range of the control input is from VREF_CTRL (max swing) to VCC (min swing). Control of the output swing can be obtained by using a variable resistor between VREF_CTRL and VCC_TXQ through a wiper driving TXVCTRL. Setting TXVCTRL to VCC_TXQ sets the output swing to min swing. Refer to the “Interface Applications” and “Output Stage” sections for more details. 11 TXVT January 2006 Pin Description LOOPBACK Mode Control. TTL/CMOS control input. LOOPBACK is an active HIGH signal used to control the LOOPBACK MUX. LOOPBACK is internally connected to a 25kW pulldown resistor and will default to a LOW state if left open. VTH = VCC/2. Input Termination Center-Tap. Each side of the transmitter differential input pair terminates to the TXVT pin. The TXVT pin provides a center-tap to a termination network for maximum interface flexibility. Refer to the “Input Stage” section for more details. 4 M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L Outputs Pin Number Pin Name 22 LOS 19 17, 16 LOSLVL RXQ, /RXQ Pin Description Loss-of-Signal Output. TTL-compatible output with internal 4.75kW pull-up resistor. Loss-ofSignal asserts to logic HIGH when the receiver input amplitudes fall below the threshold set by LOSLVL. RX Loss-of-Signal Level Set. A resistor (RLOSLVL) connected between LOSLVL and VCC sets the threshold for the data input amplitude at which the LOS output is asserted. Default is max sensitivity. LOSLVL is used to set the Loss-of-Signal (LOS) voltage. It is internally connected to a 2.8kW pull-down resistor to an internal VREF voltage source. See “Typical Operating Characteristics,” and “Application Implementation” sections for more details. Receiver Differential Output. Output is CML compatible. Refer to the “Truth Table” and “Output Stage” sections for more details. Unused output pair may be left open. The output is designed to drive 400mV (800mVPP) into 50W to VCC or 100W across the pair. 5, 6 TXQ, /TXQ Transmitter differential Variable Swing Output. Output is LVPECL-compatible. Please refer to the “Truth Table” section for details. Unused output pair may be left open. Each output is designed to drive 80mV (min) to 800mV (typ) into 50_ to VCC-2V depending on TXVCTRL. 8 VREF_CTRL Transmitter Output Reference Voltage. Output biases to VCC_TXQ-1.3V. Connecting VREF_CTRL to TXVCTRL sets the transmitter output swing to max swing. TXVREF-AC Transmitter Input Reference Voltage. This output biases to VCC-1.3V. It is used when AC coupling the transmitter input. For AC-coupled applications, connect TXVREF-AC to the TXVT pin and bypass with a 0.01µF low ESR capacitors to VCC. See “Input Stage” section for more details. Maximum sink/source current is ±1.5mA. 10 Power Pins Pin Number Pin Name Pin Description 3, 24 GND, Exposed Pad 12, 15, 18 VCC 3.3V ±10% Positive Power Supply. Bypass with 0.1µF//0.01µF low ESR capacitors and place as close to each VCC pins as possible. Power pins are not connected internally and must be connected to the same power supply externally. 21 VCC_RXIN 3.3V ±10% Receive Input Power Supply. Bypass with 0.1µF//0.01µF low ESR capacitors and place as close to the VCC_RXIN pin as possible. Power pins are not connected internally and must be connected to the same power supply externally. 4 VCC_TXQ 3.3V ±10% Output Transmit Power Supply. Bypass with 0.1µF//0.01µF low ESR capacitors and place as close to the VCC_TXQ pin as possible. Power pins are not connected internally and must be connected to the same power supply externally. Ground. GND pins and exposed pad must be connected to the same ground plane. Truth Table LOOPBACK RXQ 0 RXIN TXIN 1 TXIN RXIN January 2006 TXQ 5 M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (VCC, VCC_TXQ, VCC_RXIN) .........................–0.5V to +4.0V Input Voltage LOSLVL.............................................. VREF –1.2V to VCC LOOPBACK ................................................–0.5V to VCC /TXEN, /RXEN ............................................–0.5V to VCC TXVCTRL.............................VREF_CTRL –1.2V to VCC TXIN, /TXIN.................................................–0.5V to VCC LVPECL Output Current (IOUT) TXQ, /TXQ Continuous ...........................................................±50mA Surge..................................................................±100mA Source or Sink Current on TXVT ..................................................................±100mA LOS ........................................................................±5mA RXQ, /RXQ...........................................................±25mA RXIN, /RXIN.........................................................±10mA TXIN, /TXIN..........................................................±50mA TXVREF-AC, VREF-CTRL ..................................±2mA Lead Temperature (soldering, 20sec.) ....................... 260°C Storage Temperature (Ts) ......................... –65°C to +150°C Supply Voltage (VCC, VCC_TXQ, VCC_RXIN) ..................+3.0V to +3.6V Ambient Temperature (TA) ....................–40°C to +85°C (3) Package Thermal Resistance QFN (qJA) Still-Air.......................................................50°C/W QFN (yJB) Junction-to-Board .....................................30°C/W DC Electrical Characteristics(4) TA = –40°C to +85°C, unless otherwise stated. Symbol Parameter Min Typ Max Units VCC Power Supply Condition 3 3.3 3.6 V VCC_TXQ Transmit Power Supply 3 3.3 3.6 V VCC_RXIN Receive Power Supply ICC Power Supply Current 3 3.3 3.6 V 100 150 mA Min Typ Max Units No load, max. VCC Receiver Input DC Electrical Characteristics VCC_RXIN = 3.3V ±10%; TA = –40°C to +85°C, unless otherwise stated. Symbol Parameter Condition RIN Input Resistance (RXIN to VREF) 45 50 55 Ω RDIFF_IN Input Resistance (RXIN to /RXIN) 90 100 110 Ω VIN Input Voltage Swing (RXIN, /RXIN) See Figure 5a AC-coupled 10 900 mV VDIFF_IN Differential Input Voltage Swing |RXIN - /RXIN| See Figure 5b AC-coupled 20 1800 mV VREF Internal Reference Voltage VCC_RXIN -1.16 V VCC_RXIN -1.48 VCC_RXIN -1.32 Notes: 1. Permanent device damage may occur if absolute maximum ratings are exceeded. This is a stress rating only and functional operation is not implied at conditions other than those detailed in the operational sections of this data sheet. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 2. The data sheet limits are not guaranteed if the device is operated beyond the operating ratings. 3. Package thermal resistance assumes exposed pad is soldered (or equivalent) to the devices most negative potential on the PCB. qJA and yJB values are determined for a 4-layer board in still-air, unless otherwise stated. 4. The circuit is designed to meet the DC specifications shown in the above table after thermal equilibrium has been established. January 2006 6 M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L Receiver Output DC Electrical Characteristics VCC = 3.3V ±10%, RL = 100Ω across the outputs; TA = –40°C to +85°C, unless otherwise stated. Symbol Parameter Condition Min Typ Max Units VOH Output HIGH Voltage (RXQ, /RXQ) RL = 50Ω to VCC VCC –0.020 VCC -0.010 VCC V VOUT Output Voltage Swing (RXQ, /RXQ) See Figure 5a 325 400 500 mV VDIFF_OUT Differential Output Voltage Swing (RXQ, /RXQ) See Figure 5b 650 800 1000 mV ROUT Single-Ended Output Impedance 45 50 55 Ω RDIFF_OUT Differential Output Impedance 90 100 110 Ω VOFFSET Differential Output Offset +140 mV RL = 50Ω to VCC, limiting mode –140 Transmitter Input DC Electrical Characteristics VCC = 3.3V ±10%; TA = –40°C to +85°C, unless otherwise stated. Symbol Parameter Min Typ Max Units RIN Input Resistance (TXIN to TXVT) 45 50 55 Ω RDIFF_IN Differential Input Resistance (TXIN to /TXIN) 90 100 110 Ω VIH Input HIGH Voltage (TXIN, /TXIN) 1.2 VCC V VIL Input LOW Voltage (TXIN, /TXIN) 0 VIH -0.1 V VIN Input Voltage Swing (TXIN, /TXIN) See Figure 5a 0.1 VCC V VDIFF_IN Differential Input Voltage Swing |TXIN - /TXIN| See Figure 5b 0.2 VT_IN TXIN, /TXIN to VT VTXVREF-AC Output Reference Voltage VREF_CTRL VTXVCTRL January 2006 Condition V 1.28 V VCC -1.4 VCC -1.3 VCC -1.3 V Output Reference Voltage VCC -1.4 VCC -1.3 VCC -1.3 V Input Voltage (TXVCTRL) VREF_CTRL VCC V 7 M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L Transmitter Output DC Electrical Characteristics VCC_TXQ = 3.3V ±10%, RL = 50Ω to VCC_TXQ – 2V; TA = –40°C to +85°C, unless otherwise stated. Symbol Parameter VOH Output HIGH Voltage (TXQ, /TXQ) VOL Output LOW Voltage (TXQ, /TXQ) Condition TXVCTRL = VREF_CTRL Min Typ Max Units VCC_TXQ - 1.145 VCC_TXQ -1.020 VCC_TXQ -0.895 V VCC_TXQ - 1.945 VCC_TXQ - 1.820 VCC_TXQ - 1.695 V TXVCTRL = VCC_TXQ VOUT Output Voltage Swing (TXQ, /TXQ) TXVCTRL = VREF_CTRL See Figure 5a 550 TXVCTRL = VCC_TXQ See Figure 5a VDIFF_OUT Differential Output Voltage Swing (TXQ, /TXQ) TXVCTRL = VREF_CTRL See Figure 5b 1100 TXVCTRL = VCC_TXQ See Figure 5b VCC_TXQ - 1.100 V 800 mV 80 mV 1600 mV 160 mV LVTTL/CMOS INPUT DC Control Electrical Characteristics(5) VCC = 3.3V ±10%; TA = –40°C to +85°C, unless otherwise stated. Symbol Parameter Condition VIL /TXEN, /RXEN, LOOPBACK VIH /TXEN, /RXEN, LOOPBACK IIL /TXEN, /RXEN, LOOPBACK IIL@VIN = 0.5V IIH /TXEN, /RXEN, LOOPBACK IIH@VIN = VCC Min Typ Max Units 0.8 V 50 µA 300 µA 2 0 V Note: 5. /TXEN, /RXEN, and LOOPBACK have an internal pull-down 25kΩ resistor. January 2006 8 M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L LOS DC Electrical Characteristics VCC = 3.3V ±10%; TA = –40°C to +85°C. Symbol Parameter VLOSLVL LOSLVL Voltage Range VOH Output HIGH Voltage Source 100µA; VCC ≥ 3.3V VOL Output LOW Voltage Sink 2mA VSR LOS Sensitivity Range LOSAL Low LOS Assert Level LOSDL HYSL LOSAM LOSDM HYSM LOSAH LOSDH HYSH Low LOS De-assert Level Low LOS Hysteresis Medium LOS Assert Level Medium LOS De-assert Level Medium LOS Hysteresis High LOS Assert Level High LOS De-assert Level High LOS Hysteresis Condition Min Typ VREF Max Units VCC V 2.4 V 7 0.5 V 35 mVPP RLOSLVL = 10kΩ 7 2 -1 Data Pattern, Note 7 622Mbps 15 mV 3.2Gbps 10 mV 622Mbps 20 mV 3.2Gbps 15 mV 622Mbps 3 dB 3.2Gbps 5.5 dB 622Mbps 20 mV 3.2Gbps 15 mV 622Mbps 30 mV 3.2Gbps 25 mV 622Mbps 4 dB 3.2Gbps 5.5 dB 622Mbps 35 mV 3.2Gbps 30 mV 622Mbps 60 mV 3.2Gbps 55 mV 622Mbps 5 dB 3.2Gbps 5.5 dB RLOSLVL = 10kΩ 7 2 -1 Data Pattern, Note 7 RLOSLVL = 10kΩ, limiting mode 7 2 -1 Data Pattern, Note 6 and 7 RLOSLVL = 5kΩ 7 2 -1 Data Pattern, Note 7 RLOSLVL = 5kΩ 7 2 -1 Data Pattern, Note 7 RLOSLVL = 5kΩ, limiting mode 7 2 -1 Data Pattern, Note 6 and 7 RLOSLVL = 1kΩ 7 2 -1 Data Pattern, Note 7 RLOSLVL = 1kΩ 7 2 -1 Data Pattern, Note 7 RLOSLVL = 1kΩ, limiting mode 7 2 -1 Data Pattern, Note 6 and 7 Notes: Ê SD_AssertVoltage ˆ ˜˜ dB. 6. Hysteresis is defined as: 20Log10 ÁÁ Ë SD_De - assertVoltage ¯ 7. See the “Typical Operating Characteristics” section for more details on RLOSLVL and its associated LOS assert and de-assert amplitudes for a 7 7 2 -1 PRBS data pattern. See the “PRBS Discussion” section for more details on the 2 -1 PRBS data pattern. January 2006 9 M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L AC Electrical Characteristics(8) VCC = VCC_TXQ = VCC_RXIN = 3.3V ±10%, Receiver Load: RL = 100Ω across the outputs. Transmitter Load: RL = 50Ω to VCC_TXQ – 2V; TA = –40°C to +85°C, unless otherwise stated. Receiver and Transmitter Symbol Parameter Condition Min Typ tJITTER Deterministic Jitter (DJ) Note 9 Random Jitter (RJ) Note 10 Crosstalk-Induced Jitter Note 11 Symbol Parameter Condition Min fMAX Maximum Operating Frequency VRXIN ≥ 10mV (20mVPP) 3.2 BW -3dB VRXIN ≥ 10mV (20mVPP) 2.5 GHz S21 Single-Ended Gain Linear mode 32 dB AV(DIFF) Differential Voltage Gain Linear mode 38 dB tr, tf Output Rise/Fall Time (20% to 80%) Limiting mode 60 LOS Frequency Range LOS Operating Frequency Range Note 12 tOFF LOS De-assert Time tON LOS Assert Time 0.7 Max Units Note 13 psPP 5 psRMS 1.2 psRMS Max Units Receiver Typ Gbps 120 ps 3.2 Gbps 0.1 0.5 µs 0.2 0.5 µs Typ Max Units 0.622 Transmitter Symbol Parameter Condition Min fMAX Maximum Operating Frequency VTXIN ≥ 100mV (200mVPP) 3.2 BW -3dB VREF_CTRL ≤ TXCTRL ≤ VCC_TXQ tr, tf Output Rise/Fall Time (20% to 80%) VTXVCTRL = VREF_CTRL Gbps 2 100 GHz 160 ps Notes: 8. High-frequency AC-parameters are guaranteed by design and characterization. 23 9. Deterministic jitter is measured with both K28.5 and 2 -1 PRBS data-pattern, measured at <fMAX. VIN = 10mV (20mVpp) RX, 100mV (200mVpp) 23 TX. See the “PRBS Discussion” section for more details on the K28.5 and 2 – 1 PRBS data pattern. 10. Random jitter is measured with a K28.7 character pattern, measured at <fMAX. VIN = 10mV (20mVpp) RX, 100mV (200mVpp) TX. See the “PRBS Discussion” section for more details on the K28.7 PRBS data pattern. 11. Crosstalk is measured at the output while applying two similar differential clock frequencies that are asynchronous with respect to each other at the inputs. 7 12. LOS is guaranteed to be chatter-free at fMAX ≥622Mpbs or fMAX ≥311MHz with VRXIN ≥10mV (20mVPP) with a 2 -1 PRBS data pattern. 13. Contact factory for limits. January 2006 10 M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L Detailed Description Receiver The receiver AC-coupled differential input distributes data to 3.2Gbps with signals as small as 10mV (20mVPP) or as large as 900mV (1.8VPP). The receiver input features an internal 50Ω input termination connected to an internal reference which optimizes the inputs for AC-coupled signals. Input signals are linearly amplified with 38dB of differential gain and the output signal is limited to 400mV (800mVPP). The receiver output buffer features 50Ω source termination resistors and a current source that provides 400mV (800mVPP) swing into 50Ω termination. The output buffers terminates to standard CML loads (100Ω across the output pair or equivalent). See the “Output Stage Receiver” section for more details. Transmitter The transmitter differential input includes Micrel’s unique, patented 3-pin input termination architecture that directly interfaces to any (AC- or DC-coupled) differential signal as small as 100mV (200mVPP) without any termination resistor network in the signal path. The transmitter output buffer terminates to standard LVPECL loads (RL = 50_ to VCC_TXQ-2V). The output buffer is a special variable swing LVPECL buffer controlled by TXVCTRL. The output buffer features emitter follower output that provides 80mV (160mVPP) to 800mV (1.6VPP) swing into 50_ transmission lines. See the next section and Figures 1a and 1b for more details on how to control the variable output swing feature. Figure 1a. Voltage Source Implementation January 2006 Figure 1b. Alternative Implementation Transmitter PECL Variable-Swing Output Buffer ∑ Connecting VREF_CTRL to TXVCTRL sets the transmitter output buffer to maximum swing ∑ Setting TXVCTRL to VCC_TXQ, sets the transmitter output buffer to minimum swing ∑ Control of the transmitter output swing buffers can be obtained by using a variable resistor connected between VREF_CTRL and VCC_TXQ with a wiper connected to TXVCTRL as shown in Figure 1b Receiver LOS The SY58621L features a chatter-free Loss-of-Signal (LOS) TTL compatible output with an internal 4.75kΩ pull-up resistor. LOS circuitry monitors the input receiver signal and asserts a signal when the input signal falls below the threshold set by the programmable LOS level set pin (LOSLVL). When the amplitude of the receiver input signal falls below the threshold, LOS is asserted HIGH with a response time of ~0.2uS. LOS can be fed into /RXEN to maintain output stability by disabling the output during a Lossof-Signal condition. Figure 2a and 2b shows the LOS connection to /RXEN. When /RXEN is HIGH, the output signal RXQ is held LOW and /RXQ is held HIGH. Typically, 2dB of LOS hysteresis is adequate to prevent the receiver output from chattering. LOS operation is optimized for data rates ≥622Mbps with an input receiver amplitude of at least 10mV (20mVPP). Due to the long time constant in slower data rates below 622Mbps, the SY58621L LOS function does not guarantee chatter-free operation for low amplitude signals. LOSLVL sets the threshold of the LOS input amplitude detection. Connecting an external resistor, RLOSLVL, 11 M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L between VCC and LOSLVL sets the input amplitude LOS detection trip-point by setting up a voltage divider between VCC and VREF (an internal voltage source set at VCC-1.3V), since there is a 2.8kΩ internal resistor connected between LOSLVL and VREF. The input voltage range of LOSLVL ranges from VCC to VREF. See the “Functional Block Diagram” section and Figures 2a and 2b, to see how RLOSLVL sets up a voltage divider between VCC and VREF. See the “LOS Output DC Electrical Characteristics” table and “Typical Operating Characteristics” section to see how different RLOSLVL values affect LOS sensitivity. connected to VCC with a wiper connected to LOSLVL, as shown in Figure 2b Figure 2a. Voltage Source Implementation Figure 2b. Alternative Implementation LOS Output ∑ Connecting the input /RXEN to the LOS output as shown in Figures 2a and 2b, maintains receiver output stability under a Loss-of-Signal condition ∑ Sensitivity of the LOS signal can be programmed using the LOSLVL input by using a variable resistor January 2006 12 M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L ∑ ≥ 2dB hysteresis is insured if RLOSLVL ≤ 10kΩ ∑ LOS is guaranteed chatter-free at f ≥ 622Mbps (311MHz) Hysteresis The SY58621L provides a minimum of 2dB of LOS hysteresis, see the Figure 3 for more details. Figure 3. LOS Hysteresis Assert/De-assert Ê SD_AssertVoltage ˆ ˜ dB. SD_De - assertVoltage ˜¯ Ë Hysteresis is defined as: 20Log10 ÁÁ Loopback To support diagnostic system testing, the SY58621L features a loopback test mode, activated by setting LOOPBACK to logic HIGH. Loopback mode enables an internal loopback path from the transmitter input to the receiver output and supports the full 3.2Gbps data rate throughput. Crosstalk The SY58621L features a patent-pending isolation between the receiver and transmitter channels. The following guide lines can be used to minimize on layout induced crosstalk: 1. Ground Stripping Ground stripping is an effective method to reduce crosstalk. Ground stripping involves running a ground trace between the receiver and transmitter channels. 2. Vertical and Horizontal Traces Another way to reduce crosstalk is to route the receiver and transmitter channels on separate layers with an embedded ground or power supply layer between the layers. When routing the traces on different layers, run the receiver traces horizontal to the transmitter traces and route the transmitter traces vertical to the receiver traces. January 2006 13 M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L PRBS Discussion LOS Testing 7 The LOS function is tested with a 2 -1 PRBS (Pseudo Random Bit Stream) data-pattern. A PRBS data7 pattern of 2 -1 is used because it is a good approximation to an 8b10b-encoded NRZ data stream. 8b10b encodes 8 bits of data and replaces it with 10 bits of symbol. The extra bits are added to improve transition density and the BER (Bit Error Rate) of the system. Power Supply Filtering Although the SY58621L is fully differential, it is recommended that the power supplies are filtered as shown in Figure 4. Deterministic Jitter Testing and the K28.5 Pattern 23 The K28.5 (11000001010011111010) and 2 -1 PRBS data-patterns are used to characterize DJ because both data patterns have lower spectral frequency content which provides a best approximation to scrambled NRZ data streams. Random Jitter Testing and the K28.7 Pattern The K28.7 (1111100000…) data pattern is used to measure RJ since the pattern is free of DJ. In addition, because the K28.7 data-pattern can be used TH st to compare the TN (N period) to the T0 (1 period), low frequency jitter components can be accumulated. Figure 4. Power Supply Filtering Scheme Item Description C1, C2, C3, C23 0.1µF Capacitor C4, C5, C6, C22 0.01µF Capacitor L1, L2, L3 1.2µH Ferrite Bead Inductor Table 1. Bill of Materials January 2006 14 M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L Typical Operating Characteristics VCC = VCC_TXQ = VCC_RXIN = 3.3V ±10%, Receiver: RL = 100Ω across the outputs. Transmitter: RL = 50Ω to VCC_TXQ –2V; TA = 25°C, unless otherwise stated. RLOSLVL (kΩ) January 2006 RLOSLVL (kΩ) 15 RLOSLVL (kΩ) M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L Single-Ended and Differential Swings Figure 5a. Single-Ended Voltage Swing Figure 5b. Differential Voltage Swing Input Stage Figure 6a. TX Simplified Differential Input Stage January 2006 Figure 6b. RX Simplified Differential Input Stage 16 M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L Output Stage Receiver Figure 7a. Receiver CML DC-Coupled Output January 2006 Figure 7b. Receiver CML AC-Coupled Output 17 Figure 7c. Receiver CML DC-Coupled Output (50Ω to VCC) M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L Transmitter The transmitters output is a variable swing LVPECL open emitter driver. LVPECL has very low output (open emitter) impedance, and small signal swing which result in low EMI. LVPECL is ideal for driving 50Ω and 100Ω-controlled impedance transmission lines. There are several techniques for terminating the LVPECL output: Parallel Termination-Thevenin Equivalent, Parallel Termination (3-Ressitor), and AC-Coupled Termination. Unused output pairs may be left floating. However, the unused half of a single-ended output must be terminated, or balanced. Figure 8a. Parallel Thevenin-Equivalent Termination Figure 8b. Parallel Termination – 3-Resistors January 2006 18 M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L Interface Applications Figure 9a. LVPECL Interface (TX DC-Coupled/RX AC-Coupled) Figure 9b. LVPECL Interface (TX AC-Coupled/RX AC-Coupled) Figure 9d. CML Interface (TX AC-Coupled/RX AC-Coupled) Figure 9e. LVDS Interface (TX DC-Coupled/RX AC-Coupled) Figure 9c. CML Interface (TX DC-Coupled/RX AC-Coupled) Related Product and Support Documentation Part Number Function Data Sheet Link SY58620L Precision 4.25Gbps CML Transceiver with Integrated Loopback www.micrel.com/product-info/products/sy58620l.shtml HBW Solutions New Products and Applications www.micrel.com/product-info/products/solutions.shtml January 2006 19 M9999-012006-B [email protected] or (408) 955-1690 Micrel, Inc. SY58621L Package Information 24-Pin QFN MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2006 Micrel, Incorporated. January 2006 20 M9999-012006-B [email protected] or (408) 955-1690