19-3026; Rev 0; 10/03 +2.97V to +5.5V, 125Mbps to 200Mbps Limiting Amplifier with Loss-of-Signal Detector Features ♦ Pin Compatible with the Mindspeed MC2045-2/MC2045-2Y ♦ 500µV Input Sensitivity (BER = 10-12) ♦ Compatible with 4B/5B Data Coding ♦ Programmable LOS Threshold The MAX3645 features an integrated power detector with complementary PECL loss-of-signal (LOS) outputs that indicate when the input power level drops below a programmable threshold. An optional squelch function holds the data outputs at static levels during a LOS condition. The MAX3645 operates from a single +3.3V or +5.0V power supply over a -40°C to +85°C temperature range. It is available in 16-pin SO and 16-pin QSOP packages. ♦ ♦ ♦ ♦ Stable LOS Threshold Over Supply Range Output Disable Function and Automatic Squelch Single +3.3V or +5.0V Power Supply 18mA Supply Current Ordering Information TEMP RANGE PIN-PACKAGE MAX3645ESE PART -40°C to +85°C 16 SO MAX3645EEE -40°C to +85°C 16 QSOP Pin Configuration Applications SONET 155Mbps Transceivers TOP VIEW Fast Ethernet Receivers FDDI 125Mbps Receivers FTTx Receivers ESCON Receivers CAZ2 1 16 TH CAZ1 2 15 N.C. GNDA 3 14 VCCE DIN+ 4 MAX3645 13 DOUT+ DIN- 5 12 DOUT- VCCA 6 11 GNDE CSD 7 10 LOS DIS 8 9 LOS SO/QSOP Typical Application Circuit VCC VCC VCC CAZ 0.1µF CSD 1nF VCC CSD VCCA CAZ1 CAZ2 VCCE N.C. 0.1µF PIN K DIN+ OUT+ MAX3644* IN DOUT+ MAX3645 DOUT- DIN- OUT0.1µF GNDA LOS TH DIS LOS GNDE 50Ω GND RTH 100Ω 50Ω 50Ω 50Ω *FUTURE PRODUCT VCC - 2V VCC - 2V ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX3645 General Description The MAX3645 limiting amplifier functions as a data quantizer and is pin compatible with the Mindspeed MC2045-2 and MC2045-2Y postamplifiers. The amplifier accepts a wide range of input voltages and provides constant-level positive emitter-coupled logic (PECL) output voltages with controlled edge speeds. MAX3645 +2.97V to +5.5V, 125Mbps to 200Mbps Limiting Amplifier with Loss-of-Signal Detector ABSOLUTE MAXIMUM RATINGS Power-Supply Voltage (VCCA, VCCE) ....................-0.5V to +7.0V Voltage at CAZ1, CAZ2, DIN+, DIN-, CSD, DIS, TH ................................-0.5V to (VCC + 0.5V) PECL Output Current (DOUT+, DOUT-, LOS, LOS) ...........50mA Differential Voltage between CAZ1 and CAZ2......-1.5V to +1.5V Differential Voltage between DIN+ and DIN- ........-1.5V to +1.5V Continuous Power Dissipation (TA = +85°C) 16-Pin SO (derate 8.7mW/°C above +85°C)................565mW 16-Pin QSOP (derate 8.3mW/°C above +85°C)...........540mW Storage Ambient Temperature Range (TS)…….-65°C to +160°C Lead Temperature (soldering, 10s)...........……………….+300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VCC = +2.97V to +5.5V, PECL outputs are terminated with 50Ω to VCC - 2V, RTH = 100Ω, CAZ = 0.1µF, CSD = 1nF, TA = -40°C to +85°C. Typical values are at VCC = +3.3V, TA = +25°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 18 27 mA 4.8 6.4 kΩ POWER SUPPLY Supply Current ICC Excludes PECL termination currents RIN Single ended; VIN = ±200mV INPUT SPECIFICATIONS Input Resistance Input Sensitivity (Note 1) VIN-MIN Input Overload (Note 1) VIN-MAX Input-Referred RMS Noise 0.5 Differential 1.0 Single ended 750 Differential 1500 Unterminated input, output offset divided by DC gain (Note 2) Input-Referred Offset Voltage Input Common-Mode Voltage 3.3 Single ended VIN-NOISE mVP-P 2 40 VCC 0.87 VCMM (Notes 2, 3) mVP-P 36 µV V 50 µVRMS VCC mV DIS Input High VIH PECL or CMOS logic VCC 1160 DIS Input Low VIL PECL or CMOS logic 0 VCC 1480 mV -10 +10 µA DIS Input Current IIL, IIH 0V ≤ VDIS ≤ VCC OUTPUT SPECIFICATIONS PECL Output-Voltage High (Notes 1, 2) VCC 1085 VCC 880 mV PECL Output-Voltage Low (Notes 1, 2) VCC 1830 VCC 1555 mV Data Output Transition Time t R , tF 20% to 80% (Notes 1, 2, 4) 0.7 1.4 ns Pulse-Width Distortion PWD (Notes 1, 2, 4, 5) 30 200 ps 2 _______________________________________________________________________________________ +2.97V to +5.5V, 125Mbps to 200Mbps Limiting Amplifier with Loss-of-Signal Detector (VCC = +2.97V to +5.5V, PECL outputs are terminated with 50Ω to VCC - 2V, RTH = 100Ω, CAZ = 0.1µF, CSD = 1nF, TA = -40°C to +85°C. Typical values are at VCC = +3.3V, TA = +25°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP 150 250 MAX UNITS TRANSFER CHARACTERISTICS Bandwidth Gain = 60dB Low-Frequency Cutoff CAZ = open 500 CAZ = 0.1µF 0.5 MHz kHz LOSS-OF-SIGNAL SPECIFICATIONS (Notes 2, 4, 6) LOS Sensitivity Range 0Ω ≤ RTH ≤ 2kΩ LOS Hysteresis 10log (VDEASSERT/VASSERT) 1.4 LOS Assert/Deassert Time (Note 7) 2.3 RTH = 0Ω, low setting 0.5 0.9 1.3 LOS Assert Level LOS Deassert Level Signal-Dectect Filter Resistance Note 1: Note 2: Note 3: Note 4: Note 5: Note 6: Note 7: RSD 2 20 2 mVP-P dB 80.0 RTH = 1kΩ, medium setting 4.8 6.6 8.3 RTH = 2kΩ, high setting 12 17 22 RTH = 0Ω, low setting 1.1 1.5 1.9 RTH = 1kΩ, medium setting 8.0 10.8 13.5 RTH = 2kΩ, high setting 20 28 36 Pin 7 14 20 26 µs mVP-P mVP-P kΩ Between sensitivity and overload, the output amplitude is >95% of the fully limited amplitude and all AC specifications are met. Guaranteed by design and characterization. Noise is derived from BER measurement. The data input transition time is controlled by a 4th-order Bessel filter with f-3dB = 0.75 × data rate. PWD = [(width of wider pulse) - (width of narrower pulse)] / 2, measured with 155Mbps 0011 pattern. All LOS specifications are measured using a 155Mbps 223 - 1 PRBS pattern. The signal at the input is switched between two amplitudes, SIGNAL_ON and SIGNAL_OFF, as shown in Figure 1. VIN SIGNAL ON 1dB 6dB MAXIMUM DEASSERT LEVEL MAXIMUM POWER-DETECT WINDOW MINIMUM ASSERT LEVEL 0V SIGNAL OFF TIME Figure 1. Signal Levels for LOS Assert/Deassert Time Measurement _______________________________________________________________________________________ 3 MAX3645 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VCC = 3.3V, PECL outputs terminated with 50Ω to VCC - 2V, RTH = 100Ω, CAZ = 0.1µF, CSD = 1nF, TA = +25°C, unless otherwise noted.) OUTPUT EYE DIAGRAM (VIN = 1mVP-P, 155Mbps, 223 - 1PRBS) SUPPLY CURRENT vs. TEMPERATURE (EXCLUDES PECL OUTPUT CURRENTS) MAX3645 toc03 MAX3645 toc01 45 40 SUPPLY CURRENT (mA) OUTPUT EYE DIAGRAM (VIN = 1500mVP-P, 155Mbps, 223 - 1PRBS) MAX3654 toc02 50 35 30 200mV/ div VCC = 5.0V 25 200mV/ div 20 15 VCC = 3.3V 10 5 -15 -40 10 35 60 1ns/div 1ns/div BIT-ERROR RATIO vs. DIFFERENTIAL INPUT VOLTAGE INPUT-REFERRED RMS NOISE vs. TEMPERATURE 85 1400 1200 RTH = 1kΩ 1000 800 RTH = 2kΩ 10-6 10-7 10-8 10-9 10-10 600 10-11 10-12 400 0.01 0.1 1 100 10 0.2 0.3 0.4 0.5 0.6 0.7 -40 0.8 -15 10 35 60 LOSS-OF-SIGNAL THRESHOLD vs. RTH (VCC = +3.3V AND +5.0V) LOSS-OF-SIGNAL HYSTERESIS vs. TEMPERATURE 60 50 40 30 20 VIN = 0.1mVP-P 0 0.2 0.5 0.7 1.0 RTH (kΩ) 1.2 1.5 1.7 2.0 155Mbps, 223 - 1 PRBS LOS DEASSERT LOS ASSERT 3.2 85 155Mbps, 223 - 1 PRBS 3.0 10log (DEASSERT/ASSERT) (dB) MAX3645 toc07 70 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 MAX3645 toc08 SMALL-SIGNAL GAIN vs. RTH DIFFERENTIAL INPUT VOLTAGE (mVP-P) TEMPERATURE (°C) 80 0 0.1 VCC = +3.3V DIFFERENTIAL INPUT VOLTAGE (mVP-P) 90 10 0 VCC = +5.0V DIFFERENTIAL INPUT VOLTAGE (mVP-P) 100 4 10-5 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 MAX3645 toc06 1600 10 155Mbps, 223 - 1 PRBS -4 2.8 2.6 MAX3645 toc09 RTH = 0Ω RTH = 100Ω BIT-ERROR RATIO 1800 10-3 MAX3654 toc04 DIFFERENTIAL OUTPUT VOLTAGE (mVP-P) 2000 INPUT-REFERRED NOISE (µVRMS) TRANSFER FUNCTION MAX3645 toc05 TEMPERATURE (°C) 20log (VOUT/VIN) (dB) MAX3645 +2.97V to +5.5V, 125Mbps to 200Mbps Limiting Amplifier with Loss-of-Signal Detector RTH = 2kΩ 2.4 2.2 2.0 1.8 RTH = 1kΩ RTH = 100Ω 1.6 1.4 1.2 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 RTH (kΩ) -40 -15 10 35 TEMPERATURE (°C) _______________________________________________________________________________________ 60 85 +2.97V to +5.5V, 125Mbps to 200Mbps Limiting Amplifier with Loss-of-Signal Detector MAX3654 toc10 100 155Mbps 0011 PATTERN 90 PULSE-WIDTH DISTORTION (ps) VIN VOUT 80 MAX3645 toc11 PULSE-WIDTH DISTORTION vs. DIFFERENTIAL INPUT VOLTAGE LOSS-OF-SIGNAL WITH SQUELCH (155Mbps, 223 - 1PRBS) 70 60 50 40 30 20 10 LOS 0 1 0.1 10µs/div 10 100 1000 10,000 DIFFERENTIAL INPUT VOLTAGE (mVP-P) DATA OUTPUT TRANSITION TIME vs. DIFFERENTIAL INPUT VOLTAGE MAX3645 toc12 3.0 TRANSITION TIME (ns) 2.5 2.0 1.5 1.0 0.5 0 0.1 1 10 100 1000 10,000 DIFFERENTIAL INPUT VOLTAGE (mVP-P) _______________________________________________________________________________________ 5 MAX3645 Typical Operating Characteristics (continued) (VCC = 3.3V, PECL outputs terminated with 50Ω to VCC - 2V, RTH = 100Ω, CAZ = 0.1µF, CSD = 1nF, TA = +25°C, unless otherwise noted.) +2.97V to +5.5V, 125Mbps to 200Mbps Limiting Amplifier with Loss-of-Signal Detector MAX3645 Pin Description PIN MINDSPEED MC2045-2 MC2045-2Y PIN NAME MAXIM MAX3645 PIN NAME 1 CAZ- CAZ2 Offset-Correction-Loop Capacitor Connection. A capacitor connected between this pin and CAZ1 sets the time constant of the offset correction loop. The offset correction is disabled when the CAZ1 and CAZ2 pins are shorted together. 2 CAZ+ CAZ1 Offset-Correction-Loop Capacitor Connection. A capacitor connected between this pin and CAZ2 sets the time constant of the offset correction loop. The offset correction is disabled when the CAZ2 and CAZ1 pins are shorted together. 3 GNDA GNDA Analog Supply Ground. Must be at the same potential as the GNDE pin. 4 DIN DIN+ Positive Data Input FUNCTION 5 DIN DIN- Negative Data Input 6 VCCA VCCA +2.97V to +5.5V Analog Supply Voltage. Must be at same potential as the VCCE pin. 7 CF CSD Signal-Detect-Filter Capacitor Connection. Connect the CSD capacitor between CSD and VCCA. 8 JAM DIS Disable Input, PECL or CMOS Compatible. Data outputs are held to a static logic 0 when DIS is asserted high. The LOS function remains active when the outputs are disabled. When connected to the LOS pin, an automatic squelch function is enabled. 9 ST LOS Positive Loss-of-Signal Output, PECL. LOS is high when the level of the input signal drops below the threshold set by the TH input. LOS is low when the signal level is above the threshold. LOS can be connected directly to DIS for automatic squelch. 10 ST LOS Negative Loss-of-Signal Output, PECL. LOS is low when the level of the input signal drops below the threshold set by the TH input. LOS is high when the signal level is above the threshold. 11 GNDE GNDE Digital Supply Ground. Must be at the same potential as the GNDA pin. 12 DOUT DOUT- Negative Data Output, PECL. A high at DIS forces DOUT- high. 13 DOUT DOUT+ 14 VCCE VCCE +2.97V to +5.5V Digital Supply Voltage. Must be at the same potential as the VCCA pin. 15 NC N.C. No Connection 16 VSET TH Positive Data Output, PECL. A high at DIS forces DOUT+ low. Loss-of-Signal Threshold Pin. Resistor (RTH) to ground sets the LOS threshold. This pin cannot be left open. Detailed Description The MAX3645 consists of gain stages, offset correction, power detector, LOS indicators, and PECL output buffers. See Figure 2 for the functional diagram. Data Input The data inputs have a single-ended input resistance of 4.8kΩ and are internally DC-biased to VCC - 0.87V (see Figure 3). External capacitors are required to AC-couple the data signals. Pattern-dependent jitter is minimized by using coupling capacitor values large enough to pass the lowest frequencies of interest (consecutive ones and zeros) with the given input resistance. Typically, 0.1µF coupling capacitors yield a -3dB frequency of 354Hz. Capacitor tolerance and input resis6 tance variation (3.3kΩ to 6.4kΩ) must be considered to accurately calculate the -3dB frequency. Capacitor values should be chosen that set the -3dB frequency at least a factor of 10 below the lowest frequency of interest. A capacitor value of 0.1µF is recommended. Gain Stage and Offset Correction The limiting amplifier provides approximately 74dB (RTH = 100Ω) of gain. This large gain makes the amplifier susceptible to small DC offsets in the signal path. To correct DC offsets, the amplifier has an internal feedback loop that acts as a DC autozero circuit. By correcting the DC offsets, the limiting amplifier improves receiver sensitivity and power-detector accuracy. _______________________________________________________________________________________ +2.97V to +5.5V, 125Mbps to 200Mbps Limiting Amplifier with Loss-of-Signal Detector MAX3645 TH VCC CSD VCC VCC - 0.87V LOS LOS 4.8kΩ POWER DETECTOR 4.8kΩ MAX3645 DIN+ DOUT+ DIN- DOUT- DIN+ DIS OFFSET CORRECTION DINESD STRUCTURES CINT CAZ1 CAZ2 Figure 2. Functional Diagram Figure 3. Equivalent Data Input Circuit The external autozero capacitor (CAZ), in parallel with internal capacitance (CINT), determines the time constant of the DC offset correction loop. With CAZ = 0.1µF (recommended), the -3dB frequency cutoff of the signal path is typically 0.5kHz. detector time constant, which determines the LOS assert/deassert time. With C SD = 1nF the assert/ deassert time is in the range of 2.3µs to 80µs. This provides a long enough time constant to avoid false triggering due to variations in mark density. Power Detector and LOS Indicators Disable Function The external resistor RTH sets the gain of the first limiting stage. This gain setting controls the threshold at which the power detector indicates an LOS condition. Power detection is accomplished by rectifying and lowpass filtering the data signal, then comparing it to the programmed threshold voltage. A hysteresis of 2dB prevents the LOS output from chattering when the input signal is near the threshold. When the DIS input is forced high, the disable function is enabled, which holds DOUT+ low and DOUT- high. The disable function is used to prevent the data outputs from toggling due to noise when no signal is present. The LOS output can be connected to the DIS input for automatic squelch. PECL Output Buffer The data outputs (DOUT+, DOUT-) and the loss-of-signal outputs (LOS+, LOS-) are PECL outputs. The equivalent PECL output circuit is shown in Figure 4. Applications Information Programming LOS Assert/Deassert Levels The appropriate value of RTH is determined by using the Loss-Of-Signal Threshold vs. R TH graph in the Typical Operating Characteristics. LOS Time Constant The lowpass filter of the power detector comprises a 20kΩ on-chip resistor (RSD) and an external capacitor (CSD). The CSD capacitor value determines the power- PECL Output Terminations The proper termination for a PECL output is 50Ω to (VCC - 2V), but other standard termination techniques can be used. For more information on PECL terminations and how to interface with other logic families, refer to Maxim Application Note HFAN-01.0: Introduction to LVDS, PECL, and CML. Layout Considerations For best performance, use good high-frequency layout techniques. Filter power supplies, keep ground connections short, and use multiple vias where possible. Power-supply decoupling should be placed close to the VCC pins. Minimize the distance from the preamplifier and use controlled-impedance transmission lines to interface with the outputs when possible. _______________________________________________________________________________________ 7 +2.97V to +5.5V, 125Mbps to 200Mbps Limiting Amplifier with Loss-of-Signal Detector MAX3645 Chip Information TRANSISTOR COUNT: 1026 PROCESS: Silicon bipolar VCC DOUT+/LOS DOUT+/LOS ESD STRUCTURES Figure 4. Equivalent PECL Output Circuit 8 _______________________________________________________________________________________ +2.97V to +5.5V, 125Mbps to 200Mbps Limiting Amplifier with Loss-of-Signal Detector N E H INCHES MILLIMETERS MAX MIN 0.069 0.053 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050 MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20 0.40 SOICN .EPS DIM A A1 B C e E H L 1.27 VARIATIONS: 1 INCHES TOP VIEW DIM D D D MIN 0.189 0.337 0.386 MAX 0.197 0.344 0.394 MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.00 N MS012 8 AA 14 AB 16 AC D A B e C 0 -8 A1 L FRONT VIEW SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, .150" SOIC APPROVAL DOCUMENT CONTROL NO. 21-0041 REV. B 1 1 _______________________________________________________________________________________ 9 MAX3645 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) QSOP.EPS MAX3645 +2.97V to +5.5V, 125Mbps to 200Mbps Limiting Amplifier with Loss-of-Signal Detector PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH 21-0055 E 1 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.