19-1550; Rev 3; 7/02 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers ♦ Selectable Laser Pinning (Common Cathode or Common Anode) (MAX3286/MAX3296) ♦ 30mA Laser Modulation Current ♦ Temperature Compensation of Modulation Current ♦ Automatic Laser Power Control or Constant Bias Current ♦ Integrated Safety Circuits ♦ Power-On Reset Signal ♦ QFN Package Available Ordering Information PART PIN-PACKAGE 0°C to +70°C 28 QFN (5mm x 5mm)** MAX3286CHJ 0°C to +70°C 32 TQFP (5mm x 5mm) MAX3286C/D 0°C to +70°C Dice* Ordering Information continued at end of data sheet. *Dice are designed to operate from TJ = 0°C to +110°C, but are tested and guaranteed only at TA = +25°C. **Exposed pad. VCC VCC GND 22 23 OUT- OUT+ 24 25 VCC 26 28 GND 27 TC TOP VIEW MODSET Pin Configurations FAULT 1 21 BIASDRV FAULT 2 20 SHDNDRV 19 GND 18 MON POR 3 GND 4 EN 5 17 MD EN 6 16 POL PORDLY 7 15 POL 9 10 11 12 13 14 IN+ IN- GND REF MAX3286 MAX3296 LV GND Typical Application Circuits and Selector Guide appear at end of data sheet. TEMP RANGE MAX3286CGI VCC Gigabit Ethernet Optical Transmitter Fibre Channel Optical Transmitter ATM LAN Optical Transmitter ♦ +3.0V to +5.5V Supply Voltage 8 Applications ♦ 7ps Deterministic Jitter (MAX3296) 22ps Deterministic Jitter (MAX3286) FLTDLY The MAX3286/MAX3296 are available in a compact, 5mm ✕ 5mm, 28-pin QFN package; a 5mm ✕ 5mm, 32-pin TQFP package; or in die form. The MAX3287/MAX3288/ MAX3289 and MAX3297/MAX3298/MAX3299 are available in a 16-pin TSSOP-EP package. Features GND QFN* *Exposed pad is connected to GND. Pin Configurations continued at end of data sheet. ________________________________________________________________ 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 MAX3286–MAX3289/MAX3296–MAX3299 General Description The MAX3286/MAX3296 series of products are highspeed laser drivers for fiber optic LAN transmitters, optimized for Gigabit Ethernet applications. Each device contains a bias generator, laser modulator, and comprehensive safety features. Automatic power control (APC) adjusts the laser bias current to maintain average optical power at a constant level, regardless of changes in temperature or laser properties. For lasers without a monitor photodiode, these products offer a constant-current mode. The circuit can be configured for use with conventional shortwave (780nm to 850nm) or longwave (1300nm) laser diodes, as well as verticalcavity surface-emitting lasers (VCSELs). The MAX3286 series (MAX3286–MAX3289) is optimized for operation at 1.25Gbps, and the MAX3296 series (MAX3296–MAX3299) is optimized for 2.5Gbps operation. Each device can switch 30mA of laser modulation current at the specified data rate. Adjustable temperature compensation is provided to keep the optical extinction ratio within specifications over the operating temperature range. This series of devices is optimized to drive lasers packaged in low-cost TO-46 headers. Deterministic jitter (DJ) for the MAX3286 is typically 22ps, allowing a 72% margin to Gigabit Ethernet DJ specifications. These laser drivers provide extensive safety features to guarantee single-point fault tolerance. Safety features include dual enable inputs, dual shutdown circuits, and a laser-power monitor. The safety circuit detects faults that could cause dangerous light output levels. A programmable power-on reset pulse initializes the laser driver at startup. MAX3286–MAX3289/MAX3296–MAX3299 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers ABSOLUTE MAXIMUM RATINGS Supply Voltage at VCC ..........................................-0.5V to +7.0V Voltage at EN, EN, PORDLY, FLTDLY, LV, IN+, IN-, REF, POL, POL, MD, MON, BIASDRV, MODSET, TC.......................................................-0.5V to (VCC + 0.5V) Voltage at OUT+, OUT- .........................(VCC - 2V) to (VCC + 2V) Current into FAULT, FAULT, POR, SHDNDRV....-1mA to +25mA Current into OUT+, OUT- ....................................................60mA Continuous Power Dissipation (TA = +70°C) 32-Pin TQFP (derate 14.3mW/°C above +70°C).........1100mW 28-Pin QFN (derate 28.7mW/°C above +70°C) ..........2300mW 16-Pin TSSOP (derate 27mW/°C above +70°C) .........2162mW Operating Temperature Range...............................0°C to +70°C Operating Junction Temperature Range ..............0°C to +150°C Processing Temperature (die) .........................................+400°C Storage Temperature Range .............................-55°C to +150°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 = +3.0V to +5.5V, TA = 0°C to +70°C, unless otherwise noted. Typical values are at VCC = +3.3V, RTC = open and TA = +25°C; see Figure 1a.) PARAMETER SYMBOL CONDITIONS Supply Current ICC Figure 1a, RMOD = 1.82kΩ Data Input Voltage Swing VID Total differential signal, peak-to-peak, Figure 1a 0 ≤ VPIN ≤ VCC TTL Input Current TTL Input High Voltage VIH TTL Input Low Voltage VIL FAULT, FAULT Output High Voltage VOH IOH = -100µA FAULT, FAULT Output Low Voltage VOL IOL = 1mA MIN TYP MAX UNITS 52 75 mA 200 1660 mV -100 +100 µA 2 V 0.8 2.4 V V 0.4 V +1 µA BIAS GENERATOR (Note 1) BIASDRV Current, Shutdown EN = GND -1 BIASDRV Current Sink FAULT = low, VBIASDRV ≥ 0.6V 0.8 BIASDRV Current Source FAULT = low, VBIASDRV ≤ VCC - 1V 0.8 REF Voltage IREF ≤ 2mA, MON = VCC 2.45 2.65 2.85 V APC loop is closed 1.55 1.7 1.85 V 0.4 1.2 MD Nominal Voltage MD Voltage During Fault VMD mA Common-cathode configuration V Common-anode configuration 2 VCC - 0.8 MD Input Current Normal operation (FAULT = low) -2 +0.16 +2 µA MON Input Current VMON = VCC 0.44 6 µA POWER-ON RESET POR Threshold LV = GND 3.9 4.5 LV = open 2.65 3.00 POR Hysteresis 150 V mV FAULT DETECTION REF Fault Threshold 2.95 MD High Fault Threshold VMD + 5% VMD + 20% MD Low Fault Threshold VMD - 20% VMD - 5% MON Fault Threshold MAX3286/MAX3288/MAX3296/MAX3298 VCC 600 MODSET, TC Fault Threshold 2 _______________________________________________________________________________________ V VCC 480 mV 0.9 V 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers (VCC = +3.0V to +5.5V, TA = 0°C to +70°C, unless otherwise noted. Typical values are at VCC = +3.3V, RTC = open and TA = +25°C; see Figure 1a.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS SHUTDOWN ISHDNDRV = 10µA, FAULT asserted Voltage at SHDNDRV VCC - 0.4 ISHDNDRV = 15mA, FAULT not asserted 0 VCC - 1.2 ISHDNDRV = 1mA, FAULT not asserted 0 VCC - 2.4 V LASER MODULATOR Data Rate MAX3286 series 1.25 MAX3296 series 2.5 Minimum Laser Modulation Current Gbps 2 Maximum Laser Modulation Current Tolerance of Modulation Current Modulation-Current Edge Speed RL ≤ 25Ω 30 RMOD = 1.9kΩ (iMOD = 30mA) -10 +10 RMOD = 13kΩ (iMOD = 5mA) -15 +15 130 220 MAX3296 series 90 150 RMOD = 13kΩ (iMOD = 5mA) 46 65 RMOD = 4.1kΩ (iMOD = 15mA) 29 45 RMOD = 1.9kΩ (iMOD = 30mA) 22 35 RMOD = 13kΩ (iMOD = 5mA) 14 35 RMOD = 4.1kΩ (iMOD = 15mA) 8 22 RMOD = 1.9kΩ (iMOD = 30mA) 7 20 MAX3286 series 2 8 MAX3296 series 2 4 15 200 MAX3286 series Deterministic Jitter (Note 2) MAX3296 series Random Jitter, RMS (Note 3) Tempco = max, RMOD = open; Figure 5 4000 Tempco = min, RTC = open; Figure 5 Differential Input Resistance Single ended ps 42 ps µA ppm/°C 50 620 Output Resistance % ps Shutdown Modulation Current Modulation-Current Temperature Coefficient mA MAX3286 series 20% to 80% mA 800 980 Ω 50 58 Ω VCC - 0.3 V 0.3 1.25 µs 3 5.5 ms 22 µs 20 µs Input Bias Voltage LASER SAFETY CIRCUIT PORDLY = open POR Delay tPORDLY Fault Time tFAULT Glitch Rejection at MD CPORDLY = 0.01µF, MAX3286/MAX3296 only (Note 4) 10 _______________________________________________________________________________________ 3 MAX3286–MAX3289/MAX3296–MAX3299 ELECTRICAL CHARACTERISTICS (continued) ELECTRICAL CHARACTERISTICS (continued) (VCC = +3.0V to +5.5V, TA = 0°C to +70°C, unless otherwise noted. Typical values are at VCC = +3.3V, RTC = open and TA = +25°C; see Figure 1a.) PARAMETER SYMBOL FLTDLY Duration tFLTDLY FAULT Reset After EN, EN, or POR Transition SHDNDRV Asserted After EN = Low or EN = High CONDITIONS MIN TYP CFLTDLY = 0 0.2 1 CFLTDLY = 270pF 100 140 MAX UNITS µs MAX3286/MAX3296 only, Figure 1b, CFLTDLY = open 6 MAX3286/MAX3296 only, Figure 1b, CFLTDLY = 0.01µF 6 tRESET MAX3286/MAX3296 only, Figure 1b 1 2 µs tSHUTDN MAX3286/MAX3296 only, Figure 1b 3.5 5.5 µs EN or EN Minimum Pulse Width tEN_RESET Required to Reset a Latched Fault 10 ns µs Note 1: Common-anode configuration refers to a configuration where POL = GND, POL = VCC, and an NPN device is used to set the laser bias current. Common-cathode configuration refers to a configuration where POL = VCC, POL = GND, and a PNP device is used to set the laser bias current. Note 2: Deterministic jitter measured with a repeating K28.5 bit pattern 00111110101100000101. Deterministic jitter is the peak-topeak deviation from the ideal time crossings per ANSI X3.230, Annex A. Note 3: For Fibre Channel and Gigabit Ethernet applications, the peak-to-peak random jitter is 14.1 times the RMS jitter. Note 4: Delay from a fault on MD until FAULT is asserted high. Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) MAX3286 toc02 MAX3286 toc01 10,000 EYE DIAGRAM FLTDLY DURATION vs. CFLTDLY 10,000 MAX3286 toc03 POR DELAY vs. CPORDLY 100,000 1000 1000 DELAY (µs) DELAY (µs) MAX3286–MAX3289/MAX3296–MAX3299 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers 100 10 10 1 1 10 100 1000 10,000 CAPACITANCE (pF) 4 100 100,000 1 10 100 CAPACITANCE (pF) 1000 10,000 50ps/div 2.5Gbps, 1310nm LASER, 27 - 1 PRBS, iMOD = 15mA _______________________________________________________________________________________ 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers EN STARTUP (COMMON-ANODE CONFIGURATION) EYE DIAGRAM MD EN MAX3286 toc06 MAX3286 toc05 MAX3286 toc04 MD SHUTDOWN FAULT FAULT BIASDRV SHDNDRV OPTICAL OUTPUT OPTICAL OUTPUT 5µs/div 10µs/div 100ps/div 1.25Gbps, 1310nm LASER, 27 - 1 PRBS, imod = 15mA Pin Description PIN QFN MAX3286 MAX3296 TQFP MAX3286 MAX3296 TSSOP-EP MAX3287 MAX3297 MAX3289 MAX3299 TSSOP-EP MAX3288 MAX3298 NAME FUNCTION 1 1 — — FAULT — 2, 16, 19 — — N.C. 2 3 — — FAULT Noninverting Fault Indicator. See Table 1. 3 4 — — POR Power-On Reset. POR is a TTL-compatible output. See Figure 14. 4, 13, 19 5, 14, 22, 30 1, 6 1, 6 GND Ground 5 6 — — EN Enable TTL Input. Laser output is enabled only when EN is high and EN is low. If EN is left unconnected, the laser is disabled. EN Inverting Enable TTL Input. Laser output is enabled only when EN is low or grounded and EN is high. If EN is left unconnected, the laser is disabled. PORDLY Power-On Reset Delay. To extend the delay for the power-on reset circuit, connect a capacitor to PORDLY. See the Design Procedure section. 6 7 7 8 — — — — Inverting Fault Indicator. See Table 1. No Connect _______________________________________________________________________________________ 5 MAX3286–MAX3289/MAX3296–MAX3299 Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers MAX3286–MAX3289/MAX3296–MAX3299 Pin Description (continued) PIN QFN MAX3286 MAX3296 6 TQFP MAX3286 MAX3296 TSSOP-EP MAX3287 MAX3297 MAX3289 MAX3299 TSSOP-EP MAX3288 MAX3298 NAME FUNCTION 8 9 2 2 FLTDLY Fault Delay Input. Determines the delay of the FAULT and FAULT outputs. A capacitor attached to FLTDLY ensures proper startup. (See Typical Operating Characteristics.) FLTDLY = GND: holds FAULT low and FAULT high. When FLTDLY = GND, EN = high, EN = low, and VCC is within the operational range, the safety circuitry is inactive. 9 10 — — LV Low-Voltage Operation. Connect to GND for 4.5V to 5.5V operation. Leave open for 3.0V to 5.5V operation (Table 2). 10, 22, 23, 26 11, 25, 26, 29 3, 11, 14 3, 11, 14 VCC Supply Voltage 11 12 4 4 IN+ Noninverting Data Input 12 13 5 5 IN- Inverting Data Input 14 15 7 7 REF Reference Voltage. A resistor connected at REF to MD determines the laser power when APC is used with common-cathode lasers. 15 17 — — POL Polarity Input. POL is used for programming the laser-pinning polarity (Table 4). 16 18 — — POL Inverting Polarity Input. POL is used for programming the laser-pinning polarity (Table 4). 17 20 8 8 MD Monitor Diode Connection. MD is used for automatic power control. 18 21 — 9 MON Laser Bias Current Monitor. Used for programming laser bias current in VCSEL applications. 20 23 9 — SHDNDRV Shutdown Driver Output. Provides a redundant laser shutdown. 21 24 10 10 BIASDRV Bias-Controlling Transistor Driver. Connects to the base of an external PNP or NPN transistor. _______________________________________________________________________________________ 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers PIN QFN MAX3286 MAX3296 TQFP MAX3286 MAX3296 TSSOP-EP MAX3287 MAX3297 MAX3289 MAX3299 TSSOP-EP MAX3288 MAX3298 NAME 24 27 12 12 OUT+ Modulation-Current Output. See Typical Application Circuits. 25 28 13 13 OUT- Modulation-Current Output. See Typical Application Circuits. 27 31 15 15 MODSET 28 32 16 16 TC Temperature-Compensation Set. The resistor at TC programs the temperature-increasing component of the laser modulation current. EP — EP EP Exposed Pad Ground. This must be soldered to the circuit board ground for proper thermal performance. See Layout Considerations. Table 1. Typical Fault Conditions PIN FAULT CONDITION VCC LV = GND and VCC < 4.5V REF VREF > 2.95V POL and POL MON MD EN and EN MODSET and TC POL = POL FUNCTION Modulation-Current Set. The resistor at MODSET programs the temperature-stable component of the laser modulation current. Table 2. LV Operating Range LV OPERATING VOLTAGE RANGE (V) Open >3.0 Grounded >4.5 VMON < VCC - 540mV VMD > 1.15 ✕ VMD(nom), VMD < 0.85 ✕ VMD(nom) EN = low or open, EN = high or open VMODSET and VTC ≤ 0.8V _______________________________________________________________________________________ 7 MAX3286–MAX3289/MAX3296–MAX3299 Pin Description (continued) MAX3286–MAX3289/MAX3296–MAX3299 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers VCC ICC IOUT FERRITE BEAD* VOLTS 0.01µF VIN+ DIFFERENTIAL INPUT 100mVp-p MIN 830mVp-p MAX 0.01µF VCC OUT- OUT+ MAX3286 VCC MAX3296 VCC 50Ω VIN- 50Ω iMOD RL 25Ω BIASDRV (OPEN) INMODSET *MURATA BLM11HA102 MODULATION CONTROL RMOD 200mVp-p MIN 1660mVp-p MAX VID = VIN+ - VIN- CURRENT L = 3.9nH IN+ VID RESULTING SIGNAL L = 3.9nH iMOD TIME RL = 25Ω iMOD3/2 LASER EQUIVALENT LOAD TC Figure 1a. Output Load for AC Specification _______________Detailed Description VCC The MAX3286/MAX3296 series of laser drivers contain a bias generator with APC, laser modulator, power-on reset (POR) circuit, and safety circuitry (Figures 2a and 2b). tPORDLY POR tFAULT tRESET Bias Generator FAULT tSHUTDN SHDNDRV OPTICAL OUT tEN_RESET EN FAULT ON MD NOTE: TIMING IS NOT TO SCALE. RESET BY EN SHUTDOWN BY EN Figure 3 shows the bias generator circuitry containing a power-control amplifier, controlled reference voltage, smooth-start circuit, and window comparator. The bias generator combined with an external PNP or NPN transistor provides DC laser current to bias the laser in a lightemitting state. When there is a monitor diode (MD) in the laser package, the APC circuitry adjusts the laser-bias current to maintain average power over temperature and changing laser properties. The MD input is connected to Figure 1b. Fault Timing 8 _______________________________________________________________________________________ 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers POR CIRCUIT PORDLY the anode or cathode of a monitor photodiode or to a resistor-divider, depending on the specific application circuit. Three application circuits are supported: common-cathode laser with photodiode, commoncathode laser without photodiode, and common- anode laser with photodiode (as shown in the Design Procedure section). The POL and POL inputs determine the laser pinning (common cathode, common anode) (Table 4). The smooth-start circuitry prevents current spikes to the laser during power-up or enable; this ensures compliance with safety requirements and extends the life of the laser. The power-control amplifier drives an external transistor to control the laser bias current. In a fault condition, the power-control amplifier’s output is disabled (high POR FAULT EN EN FAULT SAFETY SHDNDRV FLTDLY POL MD POL BIASDRV BIAS GENERATOR MON REF MD OUT+ IN+ LASER MODULATOR IN- TC OUT- MODSET Figure 2a. Simplified Laser Driver Functional Diagram LV PORDLY POR FAULT REF POR CIRCUIT MAX3286 MAX3296 1.7V REF CONTROLLED REFERENCE GENERATOR FAULT MON VCC - 0.54V SAFETY CIRCUITRY FLTDLY SHDNDRV 1.97V EN EN MD BIASDRV 1.53V POL POL SMOOTHSTART BIAS GENERATOR +1.7V OUTOUT+ IN+ ININPUT BUFFER 50Ω 50Ω LASER MODULATOR VCC MODULATION CURRENT GENERATOR TC MODSET RTC RMOD Figure 2b. Laser Driver Functional Diagram _______________________________________________________________________________________ 9 MAX3286–MAX3289/MAX3296–MAX3299 LV MAX3286–MAX3289/MAX3296–MAX3299 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers impedance). This ensures that the PNP or NPN transistor is turned off, removing the laser-bias current. (See the Applications Information section.) The REF pin provides a controlled reference voltage dependent upon the voltage at MON. The voltage at REF is VREF = 2.65 - 2.25(VCC - VMON). A resistor connected at REF determines the laser power when APC is used with common-cathode lasers. See the Design Procedure section for setting the laser power. POLARITY_FAULT POL SMOOTHSTART POL Safety Circuitry ENABLE POWERCONTROL AMPLIFIER iMOD = 15mA REF RTC (kΩ) RMOD (kΩ) RTC (kΩ) REF_FAULT 2.95V MON VCC - 540mV MONITOR_FAULT Figure 3. Bias Generator Circuitry VCC MAX3286 MAX3296 50Ω 50Ω OUT+ IN+ 400Ω CURRENT SWITCH INPUT BUFFER OUT- VCC - 0.3V 400Ω IN- ENABLE CURRENT AMPLIFIER MODULATION CURRENT GENERATOR 4000ppm/°C REFERENCE 1.2V REFERENCE MOD_FAULT TC_FAULT 0.8V 0.8V 3500 26.7 1.69 53.6 3.65 162 11.5 3000 9.53 2.0 18.7 4.32 57.6 13.3 2500 5.76 2.49 11.3 5.23 34.8 16.2 TC 2000 4.12 3.16 8.06 6.49 24.9 20.0 RTC 1500 3.24 4.32 6.19 8.87 19.1 26.7 1000 2.67 6.49 5.11 13.3 15.8 40.2 500 2.26 13.3 4.22 26.7 13.3 80.6 10 BIASDRV CONTROLLED REFERENCE VOLTAGE VREF = 2.65 - 2.25 (VCC - VMON) iMOD = 5mA RMOD (kΩ) ENABLE +1.7V Table 3. RTC and RMOD Selection Table iMOD = 30mA TEMPCO (ppm/°C) RMOD RTC (kΩ) (kΩ) WINDOW COMPARATOR +1.97V Modulation Circuitry The laser driver can be used with two popular safety systems. APC maintains laser safety using local feedback. Safety features monitor laser driver operation and MD FAULT GLITCH REJECT MD The modulator circuitry consists of an input buffer, current generator, and high-speed current switch (Figure 4). The modulator drives up to 30mA of modulation current into a 25Ω load. Many of the modulator performance specifications depend on the total modulator current (IOUT) (Figure 1a). To ensure good driver performance, the voltage at OUT+ and OUT- must not be less than VCC - 1V. The amplitude of the modulation current is set with resistors at the MODSET and temperature coefficient (TC) pins. The resistor at MODSET (RMOD) programs the temperature-stable portion of modulation current, while the resistor at TC (R TC) programs the temperatureincreasing portion of the modulation current. Figure 5 shows modulation current as a function of temperature for two extremes: RTC is open (the modulation current has zero temperature coefficient) and RMOD is open (the modulation temperature coefficient is 4000ppm). Intermediate tempco values of modulation current can be obtained as described in the Design Procedure section. Table 3 is the RTC and RMOD selection table. +1.53V MODSET RMOD Figure 4. Laser Modulator Circuitry ______________________________________________________________________________________ 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers Another safety system, Open Fiber Control (OFC), uses safety interlocks to prevent eye hazards. To accommodate the OFC standard, the MAX3286/MAX3296 series provide dual enable inputs and dual fault outputs. The safety circuitry contains fault detection, dual enable inputs, latched fault outputs, and a pulse generator (Figure 6). Safety circuitry monitors the APC circuit to detect unsafe levels of laser emission during single-point failures. A single-point failure can be a short to VCC or GND, or between any two IC pins. 1.3 iMOD/(iMOD AT+ 52°C) 1.2 1.1 RTC ≥ 1.9kΩ RMOD = OPEN TEMPCO = 4000ppm/°C RTC = OPEN TEMPCO = 50ppm/°C 0.8 0.7 0.6 0 10 20 30 40 50 60 70 80 90 100 110 JUNCTION TEMPERATURE (°C) Figure 5. Modulation Current vs. Temperature for Maximum and Minimum Temperature Coefficient (FROM POR CIRCUIT) EN Fault Detection The MAX3286/MAX3296 series has extensive and comprehensive fault-detection features. All critical nodes are monitored for safety faults, and any node voltage that differs significantly from its expected value results in a fault (Table 1). When a fault condition is detected, the laser is shut down. See the Applications Information section for more information on laser safety. Shutdown The laser drivers offer dual redundant bias shutdown mechanisms. The SHDNDRV output drives an optional external MOSFET semiconductor. The bias and modulation drivers have separate, internal disable signals. 1.0 0.9 Pulse Generator During startup, the laser is not emitting light and the APC loop is not closed, triggering a fault signal. To allow startup, an internal fault-delay pulse disables the safety system for a programmable period of time, allowing the driver to begin operation. The length of the pulse is determined by the capacitor connected at FLTDLY and should be set 5 to 10 times longer than the APC time constant. The internal safety features can be disabled by connecting FLTDLY to GND. Note that EN must be high, EN must be low, and VCC must be in the operational range for laser operation. Latched Fault Output Two complementary FAULT outputs are provided with the MAX3286/MAX3296 series. In the event of a fault, these outputs latch until one of three events occurs: 1) The power is switched off, then on. PULSE GENERATOR FLTDLY tFLTDLY R VCC Q RESET DOMINANT FAULT LATCH FAULT DETECTION REF_FAULT MONITOR_FAULT MD_FAULT POLARITY_FAULT TC_FAULT MOD_FAULT FAULT S FAULT EN SHDNDRV ENABLE MAX3286 MAX3296 Figure 6. Simplified Safety Circuit Schematic ______________________________________________________________________________________ 11 MAX3286–MAX3289/MAX3296–MAX3299 force a shutdown if a fault is detected. The shutdown condition is latched until reset by a toggle of EN, EN, or power. MAX3286–MAX3289/MAX3296–MAX3299 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers rent while the resistor R TC sets the temperatureincreasing portion of the modulation current. To determine the appropriate temperature coefficient from the slope efficiency (α) of the laser, use the following equation: PORDLY VCC MAX3286 MAX3296 28k 25k Laser tempco = LV VARIABLE DELAY POR 1.2V 10 +6 [ppm / °C] where α is the slope of the laser output power to the laser current. For example, suppose a laser has a slope efficiency α 25 of 0.021mW/mA at +25°C, which reduces to 0.018mW/mA at +70°C. Using the above equation will produce a laser tempco of -3175ppm/°C. To obtain the desired modulation current and tempco for the device, the following two equations can be used to determine the required values of RMOD and RTC: = 0.7s/µF CPORDLY 36k α 70 − α 25 × α 25 (70°C − 25°C) BANDGAP Figure 7. Power-On Reset Circuit 2) EN is switched low, then high. 3) EN is switched to high, then low. Power-On Reset (POR) Figure 7 shows the POR circuit for the MAX3286/ MAX3296 series devices. A POR signal asserts low when VCC is in the operating range. The voltage operating range is determined by the LV pin, as shown in Table 2. POR contains an internal delay to reject noise on VCC during power-on or hot-plugging. The delay can be extended by adding capacitance to the PORDLY pin. The POR comparator includes hysteresis to improve noise rejection. The laser driver is shut down while VCC is out of the operating range. Design Procedure Select Laser Select a communications-grade laser with a rise time of 260ps or better for 1.25Gbps, or 130ps or better for 2.5Gbps applications. To obtain the MAX3286/ MAX3296s’ AC specifications, the instantaneous output voltage at OUT+ must remain above VCC - 1V at all times. Select a high-efficiency laser that requires low modulation current and generates low-voltage swing at OUT+. Laser package inductance can be reduced by trimming the leads. Typical package leads have inductance of 25nH/in (1nH/mm); this inductance causes a larger voltage swing across the laser. A compensation filter network can also be used to reduce ringing, edge speed, and voltage swing. R TC = RMOD = 0.21 − 250Ω tempco (iMOD ) (R TC + 250Ω)52 × tempco − 250Ω (0.19 − 48 × tempco) where tempco = -laser tempco. Figure 8a shows a family of curves derived from these equations. The straight diagonal lines depict constant tempcos. The curved lines represent constant modulation currents. If no temperature compensation is desired, Figure 8b displays a series of curves that show laser modulation current with respect to RMOD for different loads. The following useful equations were used to derive Figure 8a and the equations at the beginning of this section. The first assumes RL = 25Ω. 1.15 1.06 + × R + 250Ω RTC + 250Ω iMOD = 51 × MOD [A ] −3 1 + 4 . 0 × 10 T – 25 ° C ( ) ( ) iMOD(70°C) = iMOD(25°C) + iMOD(25°C) (tempco)(70°C – 25°C)[ A] Programming the Modulation Current Programming the Bias Current/APC Resistors at the MODSET and TC pins set the amplitude of the modulation current. The resistor RMOD sets the temperature-stable portion of the modulation cur- Three application circuits are described below: common-cathode laser with photodiode, common-cathode laser without photodiode, and common-anode laser 12 ______________________________________________________________________________________ 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers 500ppm 2000ppm with photodiode. The POL and POL inputs determine the laser pinning (common cathode, common anode) and affect the smooth-start circuits (Table 4). 2500ppm 1000ppm 3000ppm 1500ppm Common Cathode with Photodiode (Optical Feedback) In the common cathode with photodiode configuration, a servo control loop is formed by external PNP Q1, the laser diode, the monitor diode, RSET, and the powercontrol amplifier (Figure 9). The voltage at MD is stabilized to 1.7V. The monitor photodiode current (ID) is set by (VREF - VMD) / RSET = 0.95 / RSET. Determine the desired monitor current (ID), then select RSET = 0.95 / ID. The APC loop is compensated by CBIASDRV. A capacitor must be placed from BIASDRV to VCC to ensure lownoise operation and to reject power-supply noise. The time constant governs how quickly the laser bias current reacts to a change in the average total laser current (IBIASDRV + iMOD). A capacitance of 0.1µF is sufficient to obtain a loop time constant in excess of 1µs, provided that RDEG is chosen appropriately. Resistor RDEG may be necessary to ensure the APC loop’s stability when low bias currents are desired. RTC (kΩ) 3500ppm 5mA 10 10mA 15mA 20mA 25mA RL = 25Ω 30mA 1 1 100 10 1000 RMOD (kΩ) Figure 8a. RTC vs. RMOD for Various Conditions LASER MODULATION CURRENT (iMOD) (mA) 40 35 30 10Ω LOAD NOTE: RTC = OPEN 25 20 The voltage across RDEG should not be any larger than 250mV at maximum bias current. The discrete components used with the common cathode with photodiode configuration are as follows: RSET = 0.95 / ID 25Ω LOAD 15 50Ω LOAD 10 5 0 0 2 4 6 8 RMOD (kΩ) 10 12 CBIASDRV = 0.1µF (typ) RDEG = 0.25 / IBIAS(MAX) 14 Figure 8b. Laser-Modulation Current vs. RMOD Table 4. POL Pin Setup for Each Laser Configuration Type POL POL MAX3286/MAX3296 VCC GND MAX3287/MAX3297 — — MAX3286/MAX3296 VCC GND MAX3288/MAX3298 — — MAX3286/MAX3296 GND VCC DEVICE DESCRIPTION LASER PINNING Common cathode with photodiode Common cathode without photodiode VCC Common anode with photodiode MAX3289/MAX3299 — — MAX3286/MAX3296 VCC VCC Not allowed; fault occurs — MAX3286/MAX3296 GND GND Not allowed; fault occurs — ______________________________________________________________________________________ 13 MAX3286–MAX3289/MAX3296–MAX3299 1000 MAX3286–MAX3289/MAX3296–MAX3299 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers Q1 = general-purpose PNP, β >100, ft > 5MHz B1 = ferrite bead (see Bias Filter section) M1 = general-purpose PMOS device (optional) Common Cathode with Current Feedback In the common-cathode configuration with current feedback, a servo control loop is formed by an external PNP transistor (Q1), RMON, the controlled-reference voltage block, R SET , R MD , and the power-control amplifier (Figure 10). The voltage at MD is stabilized to 1.7V. The voltage at MON is set by the resistors RSET and RMD. As in the short-wavelength configuration, a 0.1µF CBIASDRV connected between BIASDRV and VCC is sufficient to obtain approximately a 1µs APC loop time constant. This improves power-supply noise rejection. To select the external components: 1) Determine the required laser bias current: IBIAS = ITH + iMOD / 2 2) Select RMD and RSET. Maxim recommends RSET = 1kΩ, RMD = 5kΩ, which results in VCC - VMON ≈ 250mV. 3) Select RMON where RMON = 250mV / IBIAS, assuming RSET = 1kΩ and RMD = 5kΩ. VCC VCC RDEG MAX3286 MAX3287 MAX3296 MAX3297 REF RSET VCC MAX3286/96 ONLY POL POL CONTROLLED REFERENCE VOLTAGE VREF = 2.65V MON VCC CBIASDRV SHDNDRV SMOOTHSTART M1 1.7V Q1 BIASDRV MD ID POWER-CONTROL AMPLIFIER PHOTO DIODE IBIAS FERRITE BEAD B1 LASER Figure 9. Common-Cathode Laser with Photodiode VCC VCC RMON MAX3286 MAX3288 MAX3296 MAX3298 REF RSET VCC MAX3286/96 POL ONLY POL CONTROLLED REFERENCE VOLTAGE VREF = 2.65V - 2.25V (VCC - VMON) MON SHDNDRV SMOOTHSTART M1 1.7V BIASDRV MD ID CBIASDRV RMD POWER-CONTROL AMPLIFIER FERRITE BEAD B1 Q1 IBIAS LASER Figure 10. Common Cathode with Current Feedback (PNP Configuration) 14 ______________________________________________________________________________________ 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers Common Anode with Photodiode In the common-anode configuration with photodiode, a servo control loop is formed by an external NPN transistor (Q1), the laser diode, the monitor diode, RSET, and the power-control amplifier. The voltage at MD is stabilized to 1.7V. The monitor photodiode current is set by ID = VMD / RSET (Figure 12). Determine the desired monitor current (ID), then select RSET = 1.7V / ID. M1 = general-purpose PMOS (optional) Programming POR Delay A capacitor may be added to PORDLY to increase the delay for which POR will be asserted low (meaning that VCC is within the operational range) when powering up the part. 100 LASER BIAS CURRENT (mA) RSET = 1kΩ RMD = 5kΩ 10 The delay will be approximately: t = 1 CPORDLY (1.4)10−6 [s] See Typical Operating Characteristics. 0.1 10 1k 100 10k RMON (Ω) Figure 11. Common Cathode without Photodiode Laser VCC MAX3286 MAX3289 MAX3296 MAX3299 VCC LASER VCC MAX3286/96 POL ONLY MONITOR DIODE VCC POL MD RSET MON ID FERRITE BEAD B1 SHDNDRV SMOOTHSTART 1.7V Q1 BIASDRV CBIASDRV POWER-CONTROL AMPLIFIER IBIAS RDEG Figure 12. Common Anode with Photodiode ______________________________________________________________________________________ 15 MAX3286–MAX3289/MAX3296–MAX3299 CBIASDRV and a degeneration resistor (RDEG) must be connected to the bias transistor (in this case NPN) to obtain the desired APC loop time constant. This improves power-supply (and ground) noise rejection. A capacitance of 0.1µF is sufficient to obtain time constants of up to 5µs in most cases. The voltage across RDEG should not be larger than 250mV at maximum bias current. The discrete components used with the common anode with photodiode configuration are summarized as follows: RSET = 1.7 / ID CBIASDRV = 0.1µF (typ) RDEG = 0.25 / IBIAS(MAX) Q1 = general-purpose NPN, β > 100, ft > 5MHz B1 = ferrite bead (see Bias Filter section) The relationship between laser bias current and RMON is shown in Figure 11. The remaining discrete components used with the common cathode without photodiode configuration are as follows: Q1 = general-purpose PNP, β >100, ft > 5MHz B1 = ferrite bead (see Bias Filter section) M1 = general-purpose PMOS device (optional) CBIASDRV = 0.1µF (typ) Designing the Bias Filter and Output Pullup Beads To reduce deterministic jitter, add a ferrite-bead inductor between the collector of the biasing transistor and either the anode or cathode of the laser, depending on type (see Typical Operating Characteristics). Use a ferrite-bead inductor with an impedance >100Ω between ƒ = 10MHz and ƒ = 2GHz, and a DC resistance < 3Ω. Maxim recommends the Murata BLM11HA102SG. These inductors are also desirable for tying the OUT+ and OUT- pins to VCC. Designing the Laser-Compensation Filter Network Laser package inductance causes the laser impedance to increase at high frequencies, leading to ringing, overshoot, and degradation of the output eye pattern. A lasercompensation filter network can be used to reduce the output load seen by the laser driver at high frequencies, thereby reducing output ringing and overshoot. The compensation components (RCOMP and CCOMP) are most easily determined by experimentation. Begin with RCOMP = 25Ω and CCOMP = 2pF. Increase CCOMP until the desired transmitter eye is obtained (Figure 13). Quick Shutdown To reduce laser shutdown time, a FET device can be attached to SHDNDRV as shown in Figure 10. This will provide a typical laser power shutdown time of less than 10µs. Applications Information Laser Safety and IEC 825 The International Electrotechnical Commission (IEC) determines standards for hazardous light emissions from fiber optic transmitters. IEC 825 defines the maximum light output for various hazard levels. The MAX3286/ MAX3296 series provides features that facilitate compliance with IEC 825. A common safety requirement is single-point fault tolerance, whereby one unplanned short, open, or resistive connection does not cause excess light output. When these laser drivers are used, as shown in the Typical Operating Circuits, the circuits respond to faults as listed in Table 5. Using these laser drivers alone does not ensure that a transmitter design is compliant with IEC 825. The entire transmitter circuit and component selections must be considered. Customers must determine the level of fault tolerance required by their applications, recognizing that Maxim products are not designed or authorized for use as components in systems intended for surgical implant 16 UNCOMPENSATED CORRECTLY COMPENSATED POWER MAX3286–MAX3289/MAX3296–MAX3299 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers OVERCOMPENSATED TIME Figure 13. Laser Compensation into the body, for applications intended to support or sustain life, or for any other application where the failure of a Maxim product could create a situation where personal injury or death may occur. Layout Considerations The MAX3286/MAX3296 series comprises high-frequency products. Their performance largely depends upon the circuit board layout. Use a multilayer circuit board with a dedicated ground plane. Use short laser package leads placed close to the modulator outputs. Power supplies must be capacitively bypassed to the ground plane with surface-mount capacitors placed near the power-supply pins. The dominant pole of the APC circuit is normally located at BIASDRV. To prevent a second pole in the APC (that can lead to oscillations), ensure that parasitic capacitance at MD is minimized. Common Questions Laser output is ringing or contains overshoot. This is often caused by inductive laser packaging. Try reducing the length of the laser leads. Modify the compensation components to reduce the driver’s output edge speed (see Design Procedure). Extreme ringing can be caused by low voltage at the OUT± pins. This may indicate that pullup beads or a lower modulation current are needed. Low-frequency oscillation on the laser output. This is more prevalent at low temperatures. The APC may be oscillating. Try increasing the value of C BIASDRV or increasing the value of RDEG. Ensure that the parasitic capacitance at the MD node is kept very small (<10pF). The APC is not needed. Connect FLTDLY to ground to disable fault detection. Connect MD to REF and MON to VCC. BIASDRV and SHDNDRV can be left open. ______________________________________________________________________________________ 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers PIN NAME CIRCUIT RESPONSE TO OVERVOLTAGE OR SHORT TO VCC CIRCUIT RESPONSE TO UNDERVOLTAGE OR SHORT TO GROUND FAULT Does not affect laser power Does not affect laser power FAULT Does not affect laser power Does not affect laser power POR Does not affect laser power Does not affect laser power PORDLY Does not affect laser power Fault state* occurs EN Normal condition for circuit operation Fault state* occurs EN Fault state* occurs Normal condition for circuit operation LV Does not affect laser power Fault state* occurs if VCC is less than +4.5V POL If POL is a TTL HIGH, a fault state* occurs; otherwise, the circuit is in normal operation If POL is a TTL LOW, a fault state* occurs; otherwise, the circuit is in normal operation POL If POL is a TTL HIGH, a fault state* occurs; otherwise, the circuit is in normal operation If POL is a TTL LOW, a fault state* occurs; otherwise, the circuit is in normal operation MON (also MAX3288/98) In common cathode without photodiode configuration, a fault state* occurs; otherwise, does not affect laser power Fault state* occurs SHDNDRV (also MAX3287/97/ 89/99) Does not affect laser power. If optional FET is used, the laser output is shut off. Does not affect laser power FLTDLY Any fault that occurs cannot be reset. Does not affect laser power. Does not affect laser power IN+, IN- Does not affect laser power Does not affect laser power REF Fault state* occurs In common-cathode configurations, a fault state* occurs; otherwise, does not affect laser power MD Fault state* occurs Fault state* occurs In common-cathode configurations, the laser bias current is shut off. In common anode, high laser power triggers a fault state.* Shutdown occurs if a shutdown FET (M1) is used. If shutdown FET is not used, other means must be used to prevent high laser power. In common-anode configurations, the laser bias current is shut off. In common cathode, high laser power triggers a fault state.* Shutdown occurs if a shutdown FET (M1) is used (Figures 9, 10). OUT+, OUT- Does not affect laser power Does not affect laser power MODSET Does not affect laser power Fault state* occurs TC Does not affect laser power Fault state* occurs BIASDRV *A fault state will assert the FAULT pins, disable the modulator outputs, disable the bias output, and assert the SHDNDRV pin. ______________________________________________________________________________________ 17 MAX3286–MAX3289/MAX3296–MAX3299 Table 5. Circuit Response to Various Single-Point Faults MAX3286–MAX3289/MAX3296–MAX3299 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers Interface Models The modulator is not needed. Leave TC and MODSET open. Connect IN+ to VCC, IN- to REF, and leave OUT+ and OUT– open. Figures 14–18 show typical input/output models for the MAX3286/MAX3296 series of laser drivers. If dice are used, replace the package parasitic elements with bondwire parasitic elements. Wirebonding Die The MAX3286/MAX3296 series uses bondpads with gold metalization. Make connections to the die with gold wire only, using ball-bonding techniques. Wedge bonding is not recommended. Bondpad size is 4mil square. Die thickness is typically 15mils (0.38mm). VCC MAX3286 MAX3296 VCC MAX3286 MAX3296 10k 4k 550Ω 2.5k 60Ω SHDNDRV FAULT, FAULT, POR Figure 15. SHDNDRV Output Figure 14. Logic Outputs VCC VCC PACKAGE 1.5nH 0.2pF PACKAGE 50Ω OUT1pF 50Ω 1pF OUT+ 1.5nH 0.2pF Figure 16. Modulator Outputs 18 ______________________________________________________________________________________ 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers MAX3286–MAX3289/MAX3296–MAX3299 VCC MAX3286 MAX3296 PACKAGE VCC 1.5nH IN+ Q1 0.2pF 1pF 400Ω VCC 1.5nH 400Ω IN- Q2 0.2pF 1pF INPUT COMMON-MODE VOLTAGE ≈ VCC - 0.3V RIN Q1, Q2 > 100kΩ Figure 17. Data Inputs VCC MAX3286 MAX3296 40Ω BIASDRV 40Ω Figure 18. BIASDRV Output ______________________________________________________________________________________ 19 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers MAX3286–MAX3289/MAX3296–MAX3299 Selector Guide DATA RATE/DEVICE 1.25Gbps LASER CONFIGURATION 2.5Gbps MAX3286 MAX3296 MAX3287 MAX3297 MAX3288 MAX3298 MAX3289 MAX3299 COMMON ANODE WITH PHOTODIODE COMMON CATHODE WITH PHOTODIODE COMMON CATHODE WITH PHOTODIODE Longwave Shortwave or VCSEL VCSEL ✓ ✓ ✓ PACKAGE 32 TQFP/28 QFN/Dice ✓ 16 TSSOP-EP ✓ 16 TSSOP-EP ✓ 16 TSSOP-EP TC MODSET GND VCC OUT- OUT+ VCC VCC Pin Configurations (continued) 32 31 30 29 28 27 26 25 TOP VIEW FAULT 1 24 BIASDRV N.C. 2 23 SHDNDRV FAULT 3 22 GND VCC 3 POR 4 21 MON IN+ 4 20 MD IN- 5 19 N.C. GND 6 GND 5 EN 6 EN PORDLY MAX3286 MAX3296 GND 1 18 POL 7 17 POL 8 16 TC FLTDLY 2 15 MODSET MAX3287 MAX3289 MAX3297 MAX3299 15 16 REF 14 N.C. LV VCC 13 GND FLTDLY 12 IN- 11 IN+ 10 16 TC 14 VCC VCC 3 13 OUT- IN+ 4 12 OUT+ IN- 5 15 MODSET 14 VCC MAX3288 MAX3298 13 OUT12 OUT+ 11 VCC GND 6 11 VCC REF 7 10 BIASDRV REF 7 10 BIASDRV MD 8 9 MD 8 9 TSSOP-EP* 9 GND 1 FLTDLY 2 TQFP SHDNDRV MON TSSOP-EP* *EXPOSED PAD IS CONNECTED TO GND. Ordering Information (continued) PART TEMP RANGE PIN-PACKAGE MAX3287CUE 0°C to +70°C 16 TSSOP-EP** MAX3288CUE 0°C to +70°C 16 TSSOP-EP** MAX3289CUE 0°C to +70°C 16 TSSOP-EP** MAX3296CGI 0°C to +70°C 28 QFN (5mm x 5mm)** MAX3296CHJ 0°C to +70°C 32 TQFP (5mm x 5mm) MAX3296C/D 0°C to +70°C Dice* MAX3297CUE 0°C to +70°C 16 TSSOP-EP** MAX3298CUE 0°C to +70°C 16 TSSOP-EP** MAX3299CUE 0°C to +70°C 16 TSSOP-EP** 20 *Dice are designed to operate from TJ = 0°C to +110°C, but are tested and guaranteed only at TA = +25°C. **Exposed pad. ______________________________________________________________________________________ 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers +3.0V TO +5.5V MAX3286/MAX3296 COMMON-CATHODE VCSEL WITH PHOTODIODE 0.01µF 0.01µF FLTDLY MON POL CBIASDRV 0.1µF PORDLY 0.01µF PMOSFET (OPTIONAL) SHDNDRV VCC EN PNP TRANSISTOR BIASDRV 0.01µF VCC IN+ FERRITE BEAD DATA INPUT 115Ω MAX3286 MAX3296 IN0.01µF 0.01µF OUT+ POR 0.01µF OUT- CCOMP FAULT 25Ω RCOMP FAULT LV POL VCC EN GND MODSET TC REF MD RMOD RTC RSET +3.0V TO +5.5V 0.01µF MAX3286/MAX3296 COMMON-CATHODE VCSEL WITHOUT PHOTODIODE 0.01µF 0.01µF 0.01µF POL FLTDLY VCC EN MON CBIASDRV 0.1µF PORDLY PNP TRANSISTOR BIASDRV VCC IN+ FERRITE BEAD DATA INPUT 115Ω 0.01µF RMON MAX3286 MAX3296 INSHDNDRV 0.01µF OUT+ 0.01µF OUT- POR FAULT CCOMP 25Ω RCOMP FAULT LV POL VCC EN GND MODSET TC RTC REF MD RMD 5k RMOD RSET 1k ______________________________________________________________________________________ 21 MAX3286–MAX3289/MAX3296–MAX3299 Typical Application Circuits 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers MAX3286–MAX3289/MAX3296–MAX3299 Typical Application Circuits (continued) +3.0V TO +5.5V 0.01µF MAX3286/MAX3296 COMMON-ANODE LASER WITH PHOTODIODE FLTDLY MON POL 0.01µF VCC EN VCC PORDLY 0.01µF 0.01µF IN+ 0.01µF MAX3286 MAX3296 IN0.01µF 18Ω OUT- DATA INPUT 115Ω CCOMP 0.01µF OUT+ RCOMP 25Ω POR FERRITE BEAD FAULT VCC FAULT LV SHDNDRV POL NPN TRANSISTOR BIASDRV EN CBIASDRV 0.1µF MD GND MODSET TC REF RDEG RMOD RTC RSET +3.0V TO +5.5V 0.01µF MAX3287/MAX3297 COMMON-CATHODE VCSEL WITH PHOTODIODE VCC RDEG CBIASDRV 0.1µF PNP TRANSISTOR BIASDRV 0.01µF VCC IN+ FERRITE BEAD DATA INPUT 115Ω MAX3287 MAX3297 IN- 0.01µF OUT+ 0.01µF 0.01µF OUT0.01µF CCOMP 25Ω FLTDLY SHDNDRV GND MODSET TC RTC REF MD RCOMP VCC RMOD RSET 22 ______________________________________________________________________________________ 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers +3.0V TO +5.5V 0.01µF MAX3288/MAX3298 COMMON-CATHODE VCSEL WITHOUT PHOTODIODE VCC MON RMON CBIASDRV 0.1µF PNP TRANSISTOR BIASDRV 0.01µF VCC IN+ FERRITE BEAD DATA INPUT 115Ω MAX3288 MAX3298 IN- 0.01µF OUT+ 0.01µF CCOMP OUT- 0.01µF 0.01µF FLTDLY 25Ω GND MODSET TC REF MD RCOMP VCC RMD 5k RMOD RTC RSET 1k +3.0V to +5.5V MAX3289/MAX3299 COMMON-ANODE LASER WITH PHOTODIODE 0.01µF VCC VCC 0.01µF IN+ 18Ω 0.01µF OUT- DATA INPUT 115Ω MAX3289 MAX3299 IN- OUT+ CCOMP 0.01µF 25Ω 0.01µF 0.01µF FERRITE BEAD RCOMP VCC FLTDLY BIASDRV CBIASDRV 0.1µF SHDNDRV GND MODSET TC NPN TRANSISTOR REF MD RDEG RTC RMOD RSET ______________________________________________________________________________________ 23 MAX3286–MAX3289/MAX3296–MAX3299 Typical Application Circuits (continued) Chip Topographies FLTDLY TC LV FAULT FAULT POR GND EN TC FLTDLY MODSET LV MODSET HF34Z-1Z HF34Z VCC VCC IN+ IN- VCC VCC OUT- IN+ OUT- OUT+ IN- OUT+ 0.072" (1.829mm) TRANSISTOR COUNT: 1154 SUBSTRATE CONNECTED TO GND 0.053" (1.346mm) TRANSISTOR COUNT: 1154 SUBSTRATE CONNECTED TO GND ______________________________________________________________________________________ BIASDRV SHDNDRV GND MON MD N.C. POL POL VCC BIASDRV REF SHDNDRV VCC GND REF MON VCC MD GND N.C. VCC POL GND 0.053" (1.346mm) 24 EN FAULT PORDLY MAX3296 FAULT POR GND EN EN PORDLY MAX3286 POL MAX3286–MAX3289/MAX3296–MAX3299 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers 0.072" (1.829mm 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers 32L QFN .EPS ______________________________________________________________________________________ 25 MAX3286–MAX3289/MAX3296–MAX3299 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.) 32L,TQFP.EPS MAX3286–MAX3289/MAX3296–MAX3299 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers 26 ______________________________________________________________________________________ 3.0V to 5.5V, 1.25Gbps/2.5Gbps LAN Laser Drivers TSSOP.EPS Maxim makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Maxim assume any liability arising out of the application or use of any product or circuit and specifically disclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters can and do vary in different applications. All operating parameters, including “typicals” must be validated for each customer application by customer’s technical experts. Maxim products are not designed, intended or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the Maxim product could create a situation where personal injury or death may occur. 27 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. MAX3286–MAX3289/MAX3296–MAX3299 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.)