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| ( DataSheet : www..com ) 1.25Gbps Limiting Amplifier MC2046-2/C Postamplifier/Quantiser for Gigabit Ethernet and Fiber Channel Applications Main Features: Low-cost IC, available as die or in QSOP16 and TSSOP20 packages. Fabricated in advanced sub-micron BiCMOS process. Very wide range of operation; suitable for up to 1.5Gbps. 4mV input sensitivity at 1.25Gbps. Pin-compatible, superior replacement for Motorola MC10SX1125 Microcosm MC2044C/MC2045-2 PinCompatible. Programmable input-signal level detect. (Onchip default, saving external components) Fully differential 3.3 volt operation. (5v supported) CMOS and PECL Link-Status variants. General Description: The MC2046-2/C is a 2nd-generation, integrated, high gain limiting amplifier intended for high speed fiberoptics based communications. Normally placed following the photodetector and transimpedance or pre-amplifier, the limiting amplifier provides the necessary gain to give PECL compatible logic outputs. The MC2046-2/C also includes a programmable signal-level detector, allowing the user to set thresholds at which the logic outputs are enabled. Capable of operating over a very wide frequency range, the MC2046-2 supports most fiberoptic industry standards, but it is especially suited to 1.06Gbps Fiber Channel and 1.25Gbps Ethernet. It is pin and functionally compatible with the Motorola MC10SX1125 and earlier Microcosm Post-amplifiers. The MC2046-2 die has both PECL and CMOS Status outputs. Packaged, the MC2046-2 has PECL Status outputs and the MC2046-2C has CMOS Status outputs. Ordering Information Part Number MC2046CT20 MC2046T20 MC2046Q16 MC2046CQ16 MC2046DIEWP MC2046WAFER Pin Package TSSOP20 TSSOP20 QSOP16 QSOP16 Waffle Pack Expanded whole 8" on a 10" grip ring VccA Cazp Cazn VccE Din Din Limiting Amp. ECL Buffer Dout Dout Level Detector Jam Buffer Jam Vdet ST Detection Reference Buffer Threshold Circuit ST GndA Vref Vset Iset GndE www..com MC2046-2/C Preliminary Issue E 22 October, 1999 Page 1 www..com Pin descriptions TSSOP 20 Or Die Pin No. Auto-zero capacitor pin. Connect Caz between this pin and Pin2. See Pin 1 May be left unconnected or else may connect resistor for programming threshold detection level - See description of Detection Threshold Circuit. 4 3 GndA Ground pin for analogue section. Connect to most negative supply. Must be at same potential as GndE. 5 4 Din Differential Data Input. 6 5 Dinb Inverse Differential Data Input 7 6 VccA Supply pin for analogue section. Connect to most positive supply. Must be at the same potential as VccE 8 7 Vref Test point for on-chip voltage reference. This pin may be left unconnected or else a capacitor may be connected between this pin and the positive supply. 11 8 Jam ECL and CMOS compatible logic input. When HIGH, data outputs Dout and Doutb are disabled (Dout being held LOW and Doutb being held HIGH). 12 9 STb1 Signal detect status output. LOW when input signal level is above detection threshold. This output may be connected to the Jam input pin. 13 10 ST1 Signal detect status output. HIGH when input signal level is above detection threshold. 14,15 11 GndE Ground pin for PECL output stage. Connect to the most negative supply. Must be at the same potential as GndA 16 12 Doutb PECL compatible differential data output. In phase with input DinbDin. 17 13 Dout PECL compatible differential data output. In phase with input DinDinb. 18,19 14 VccE Supply pin for PECL output stage. Connect to the most positive supply. Must be at the same potential as VccA. 20 16 Vset Input threshold-level setting circuit. Connect to Analogue Ground via a resistor. See Application diagram. Must be connected to ground even if function not required. 1 MC2046-2 - ECL outputs are 100k compatible. MC2046-2C - CMOS output levels. 1 2 3 1 2 Cazn Cazp Iset QSOP16 Pin No. Name Function Absolute maximum ratings Symbol Vcc Ta Tstg Parameter Power supply (Vcc-Gnd) Operating ambient Storage temperature Rating 6 -40 to +85 -65 to +150 Units V C C These are the absolute maximum ratings at or beyond which the IC can be expected to fail or be damaged. Reliable operation at these extremes for any length of time is not implied. MC2046-2/C Preliminary Issue E 22 October, 1999 Page 2 Recommended operating conditions Symbol Vcc Ta Parameter Power supply (Vcc-Gnd) Operating ambient Rating 3.0 to 5.5 -40 to +85 Units V C DC Electrical Characteristics (over recommended operating conditions) Symbol Vin Parameter Minimum input signal Maximum input signal Single-ended Differential Single-ended Differential Min. 1 2 100 1.75 -10 -1.051 -1.892 0.627 - Typ. 2.25 - Max. 0.002 0.004 tba 93 2 2.75 10 -0.879 -1.548 0.879 40 Units Vp Vp-p Vp Vp-p V V mVp-p mVp-p dB A V V V mA Vos Vn Vth Vhys Iinl VOH VOL VOH-VOL Icc Input offset voltage Input RMS noise Level detect programmability Level detect hysteresis (optical) JAM input current (at 0V) Data output HIGH Data output LOW Differential Data output Supply current (no ECL loads) min max AC Electrical Characteristics (over recommended operating conditions) Symbol BWL BWU Rin Cin Tpwd Tr,Tf Raz Tld Parameter Lower -3dB frequency Upper -3dB frequency Differential input resistance Input capacitance Pulse Width Distortion ECL out rise/fall times (20-80% points) Auto-zero output resistance Level detect time constant Min. 1000 2.8 0.5 Typ. 200 25 1 Max. 3 9.7 2 30 250 2.0 Units KHz MHz kOhms pF pS pS kOhms S Microcosm MC2046-2/MC2046-2C/MC2044C compatibility The MC2046-2/C and MC2044C are pin-compatible and functionally identical, except that the MC2044C has lower internal bandwidth to improve input sensitivity. In all cases, the C suffix indicates CMOS level Link-Status outputs, while the absence of the C indicates PECL levels. MC2046-2/C Preliminary Issue E 22 October, 1999 Page 3 Signal Path Description Input biasing The Data Input pins are internally DC biased at approx. VccA - 1V, via the Rin resistors. Although the MC2046-2 can be DC coupled, normally it will be AC coupled, using capacitors C1 & C2. Note that Rin and C1,2 form a filter to low frequencies. The capacitors must therefore be large enough to pass the lowest input frequencies (consecutive `1's or `0's) of interest. For example, setting C1,2 to 10nF will give a typical -3dB point of approx. 10KHz. Autozero circuit The MC2046-2 includes an autozero circuit. In the absence of data, the feedback amplifier and summing circuit cancel the inherent offset voltage of the signal path, keeping the comparator at its toggle point. The time constant of this circuit is set by the combination of Raz and Caz, but is not critical. Caz is normally set to 100nF. Power supply decoupling & optimising sensitivity Generally, a 4-layer board is required to achieve maximum sensitivity. A good layout on a 4+ layer board should mean ferrite suppressors (as shown) are unnecessary. Contact Microcosm for further assistance in this area. MC2046-2/C Preliminary Issue E 22 October, 1999 Page 4 Forward Gain Path block diagram. Caz 10nF O ptional Surfacemount Ferrite beads VccE Raz 10k C1 Rin 10k Rin 10k Raz 10k VccA Vcc Din Comparator Dout Dout Din C2 GndE GndA Gnd Detection Threshold Circuit block diagram VccA Ra Rd Voltage controlled current source VCCS2 Vdet Vref Voltage controlled current source VCCS1 Rb Rc Vset Iset Rvset GndA Riset Level detector The MC2046-2 provides for programmable input-signal level detection, and this may be used to automatically force the Data Outputs to a known state if the input signal falls below threshold. This is normally used to allow data to propagate only when the signal is above the users' Bit-Error-Rate (BER) requirement. It therefore also stops the data outputs toggling due to noise when no signal is present. Referring to the block diagram shown on the front page, the Detection Threshold Circuit produces a differential signal "Vdet". The Level Detector compares the input differential peak amplitude with this voltage. The Detection Threshold Circuit is shown here in detail. Vref is 0.5V below VccA. Rvset and Riset are optional and, if connected, appear in parallel with on-chip resistors Rb and Rc, respectively. For the following, let Rb' be the parallel combination of Rb and Rvset, and let Rc' be the parallel combination of Rc and Riset. MC2046-2/C Preliminary Issue E 22 October, 1999 Page 5 Voltage controlled current source VCCS1 causes the current through Ra to be 0.5V/Ra. The voltage at pin Vset is defined by this current and resistance Rb' . This voltage is applied across resistance Rc' by voltage controlled current source VCCS2. The current through Rd is thus defined and the voltage Vdet is given by: Vdet = 0.5V Rb' . Rd Ra. Rc' Ra Rb Rc Rd 2.8K 5.6K 1.2K 60 The nominal values of the on-chip resistors are The absolute values of these resistors have uncertainty of +/-20%, however the ratios are well defined. With neither Rvset nor Riset connected: Detection Level = Vdet = 50mV (i.e. 50mV diff peak or 100mVdiff peak - peak With Rvset resistor connected: Detection Level = Vdet = ( Rb / / Rvset ) V(Vset) = 0.025V Vdiff peak 20 Ra Application Note on 50 loads. When running PECL outputs into a capacitively coupled 50 load, 180 pull-down resistors are recommended. If higher impedance lines are used to matched to a higher impedance load, then larger pull-down resistors may be used. MC2046-2/C Preliminary Issue E 22 October, 1999 Page 6 Die layout (not to scale) Iset Cazp Cazn Vset VccE VccE GndA Din 1.12mm Dinb VccA MC2046-2 Microcosm C 1998 Dout Doutb GndE GndE Vref Jam StB- StB- St- StECL C ECL C I/O Pad openings are 90 square Pad pitch min. 130 1.49mm Pinouts: drawings not to scale 1 Cazn Cazp GndA Din Dinb VccA Vref Jam 8 9 Microcosm MC2046-2/C WkWkYrYr 16 Vset NC VccE Dout Doutb GndE ST STb Cazn Cazp Iset GndA Din Dinb VccA Vref NC NC 1 20 Vset VccE Microcosm MC2046-2/C WkWkYrYr VccE Dout Doutb GndE GndE ST STb Jam 10 150Mil, Narrow-body QSOP16 11 6.5x4.4mm TSSOP20 package This specification is derived from simulation results and tests on engineering samples. These specifications may yet change prior to full product release. MC2046-2/C Preliminary Issue E 22 October, 1999 Page 7 World Wide Sales Offices Headquarters Newport Beach Mindspeed Technologies 4000 MacArthur Boulevard, East Tower Newport Beach, CA 92660 Phone: (949) 579-3000 Americas US Southwest/Pacific Southwest Newbury Park Phone: (805) 786-2000 Fax: (805) 480-4486 Europe Europe Central Germany, Switzerland Eastern Europe and Turkey Phone: (49) 89 829 1320 Fax: (49) 89 834 2734 US Northwest/Pacific Northwest Santa Clara Phone: (408) 423-4500 Fax: (408) 249-7113 Europe Mediterranean Italy, Spain and Portugal Phone: (39) 02 9317 9911 Fax: (39) 02 9317 9913 US North Central Illinois/Colorado Phone: (630) 799-9300 Fax: (630) 799-9325 Europe North UK, Ireland and Scandinavia Phone: 44 (0) 118 920 9500 Fax: 44 (0) 118 920 9595 US South Central - Texas Phone: (972) 735-1540 Fax: (972) 407-0639 UK Phone: 44 (0) 1925-661968 Fax: 44 (0) 1925-661800 US Northeast / Canada Phone: (613) 271-2358 Fax: (613) 271-2359 Massachusetts Phone: (978) 244-7680 Fax: (978) 244-6868 Europe South France, Belgium and Netherlands Phone: +33 (0) 1 56 30 80 40 Fax: +33 (0) 1 56 30 80 20 US Southeast - North Carolina Phone: (919) 858-9110 Fax: (919) 858-8669 Europe - Israel/Greece Phone: (972) 9961-5100 Fax: (972) 9957 5166 US Florida / South America Europe - Finland Phone: (35) 892316 6495 Fax: (35) 892316 6220 www.mindspeed.com Phone: (727) 799-8406 Fax: (727) 799-8306 US Mid-Atlantic - Pennsylvania Phone: (215) 244-6784 Fax: (215) 244-9292 San diego Phone: (858) 228 3000 Fax: (858) 228 3000 Santa Clara Phone: (408) 423 4500 Fax: (408) 249 7133 Asia Taiwan Phone: (886-2) 8789-8366 Fax: (886-2) 8789-8366 China - Hong Kong Phone: 86-755-518-2495 Fax: 86-755-518-3024 Hong Kong Phone: 852-2-827-0181 Fax: 852-2-827-6488 China - Central and North Phone: (86-21) 6350-5701 Fax: (86-21)-6350-5702 Korea Phone: 82-2-565-2880 Fax: 82-2-528-4301 Mindspeed Technologies Japan Company Limited. Phone: (81-3) 5380 1730 Fax: (81-3) 5371 1501 |
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