19-1645; Rev 0; 1/00 MAX3289 Longwave (Common Anode) Evaluation Kit Features ♦ Drives Common-Anode Lasers ♦ Socket for Laser Insertion ♦ LED Fault Indicator ♦ Evaluates Either MAX3289 (installed) or MAX3299 ♦ Adjustable Laser Bias Current ♦ Adjustable Laser Modulation-Current Temperature Coefficient ♦ Configured for Electrical Operation, No Laser Necessary Ordering Information PART MAX3289EVKIT *Exposed Pad TEMP. RANGE IC PACKAGE 0°C to +70°C 16 TSSOP-EP* Component List DESIGNATION QTY DESCRIPTION C7, C9, C10, C15, C16, C21, C26, C44, C48, C49 10 C18 0 Open, user supplied (0402)** C24 1 10µF, 16V ±10% tantalum capacitor AVX TAJC106K016 C33 1 0.01µF, 10V min ±10% X7R ceramic capacitor (0603) C50 1 DESIGNATION QTY DESCRIPTION R1 1 0Ω resistor (0402) R6 1 115Ω ±1% resistor (0402) R7, R14 2 100kΩ variable resistors Bourns Digi-Key 3296W-104-ND R8 1 50kΩ variable resistor Bourns Digi-Key 3296W-503-ND R15, R40 2 36Ω ±5% resistors (0603) R16 1 18Ω ±5% resistor (0402) 0.1µF, 10V min ±10% X7R ceramic capacitor (0603) R17 1 24.9Ω ±1% (0402)** R19 1 49.9Ω ±1% resistor (0402) R27 1 6.8Ω ±1% resistor (0402) R39 1 1kΩ ±5% resistor (0402) J11, J12, J16 3 SMA connectors (edgemount) EFJohnson 142-0701-801 or Digi-Key J502-ND Q3 1 Zetex FMMT491A Q7 1 Zetex FMMT591A U1 2 Installed: MAX3289CUE (16-pin TSSOP-EP); included but not installed: MAX3299CUE (16-pin TSSOP-EP) U6 1 MAX4322EUK (5-pin SOT23) 0.01µF, 10V min ±10% X7R ceramic capacitors (0402) D2 0 Open, user supplied (laser diode and photodiode assembly, Figure 1) L2 1 Ferrite bead, included but not installed Murata BLM11HA102SG L3, L6 2 Ferrite beads Murata BLM11HA102SG L7 1 Ferrite bead Murata BLM11HA601SG JU2 1 3-pin header (0.1in centers) JU10 1 2-pin header (0.1in centers) Digi-Key S1012-36-ND J8, J9 2 Test points Mouser 151-203 TP1, TP2, TP11, TP12, TP13 5 Test points Mouser 151-203 **These items are part of the compensation network that reduces overshoot and ringing. Parasitic series inductance introduces a zero into the laser’s frequency response. R18 and C17 add a pole to cancel this zero. The optimal values depend upon the laser used. Maxim recommends C18 = 2pF and R17 = 24.9Ω as a starting point. ________________________________________________________________ Maxim Integrated Products 1 For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. Evaluates: MAX3289/MAX3299 General Description The MAX3289 evaluation kit (EV kit) is an assembled, surface-mount demonstration board that provides easy optical and electrical evaluation of the MAX3289 1.25Gbps laser driver or the MAX3299 2.5Gbps laser driver in the common-anode configuration. This configuration allows evaluation of the MAX3289/MAX3299 with long-wavelength laser diodes. Long-wavelength (1310nm and greater) laser diodes are typically packaged with the laser diode’s anode connected to the photodetector’s cathode. Evaluates: MAX3289/MAX3299 MAX3289 Longwave (Common Anode) Evaluation Kit Electrical Quick Start with Simulated Photodiode Feedback 1) Short shunts SP9 and SP10 to use the photodiode emulator circuitry (see Emulating a Photodiode During Electrical Evaluation). 2) Make sure nothing is installed in the laser socket (Figure 1). 3) Ensure that R27 is installed. 4) Ensure that L2 is not installed. 5) Confirm that C18 is open. Since the laser is not installed, no compensation network is required. 6) Set the R14 (RSET) potentiometer to midscale by turning the screw clockwise until a faint click is felt, then counterclockwise for 15 full revolutions (30 full revolutions in the 0 to 100kΩ range of the multiturn potentiometer). This sets the regulation point for the simulated photodiode current to 1.7V / 50kΩ = 34µA. The photodiode emulator circuit regulates the DC bias current into Q3 to 28 · 34µA ≅ 1mA. 7) Set the R8 (RMOD) potentiometer to maximum resistance by turning the screw counterclockwise until a faint click is felt (30 full revolutions in the 0 to 50kΩ range of the multiturn potentiometer). This minimizes the modulation current. 8) Set the R7 (RTC) potentiometer to maximum resistance by turning the screw counterclockwise until a faint click is felt (30 full revolutions in the 0 to 100kΩ range of the multiturn potentiometer). This minimizes the temperature coefficient of the modulation current. 9) Ensure there is no jumper on JU10 (FLTDLY). This enables the safety circuitry. 10) Attach a 50Ω characteristic impedance cable between the J16 SMA output connector and the input of the oscilloscope. Ensure the oscilloscope input is 50Ω terminated. 11) Attach differential sources to SMA connectors J11 and J12. Each source should have peak-to-peak amplitude between 100mV and 830mV. 12) Apply either +3.3V or +5V power to the board at the J8 (VCC) and J9 (GND) test points. Put a jumper across pins 1 and 2 of JU2. Set the current limit to 300mA. 13) While monitoring the voltage between TP2 and TP13, adjust R14 (RSET) until the desired DC bias current is obtained. Turning the R14 potentiometer screw counterclockwise increases the DC bias current. 14) While monitoring the J16 SMA connector output on the oscilloscope, adjust R8 (RMOD) until the desired 2 modulation current is obtained. Turning the R8 potentiometer screw clockwise increases the modulation current. Optical Quick Start with Photodiode Feedback 1) Ensure that SP9 and SP10 are open. This ensures that the photodiode emulator circuitry is not connected. 2) Remove R27. 3) Install L2. 4) Connect a laser to the board (Figure 1). 5) Set the R14 (RSET) potentiometer to maximum resistance by turning the screw counterclockwise until a faint click is felt, then counterclockwise for 15 full revolutions (30 full revolutions in the 0 to 100kΩ range of the multiturn potentiometer). This sets the regulation point for the photodiode current to 1.7V / 50kΩ = 34µA. The resulting laser bias current depends upon the relationship between laser power and photodiode output current. WARNING: Consult your laser data sheet to ensure that 34µA of photodiode monitor current does not correspond to excessive laser power. 6) Set the R8 (RMOD) potentiometer to maximum resistance by turning the screw counterclockwise until a faint click is felt (30 full revolutions in the 0 to 50kΩ range of the multiturn potentiometer). This minimizes the modulation current (AC drive applied to laser). 7) Set the R7 (RTC) potentiometer to maximum resistance by turning the screw counterclockwise until a faint click is felt (30 full revolutions in the 0 to 100kΩ range of the multiturn potentiometer). This minimizes the temperature coefficient of the modulation current. 8) Attach a 50Ω SMA terminator to J16 to match the laser loading. 9) Ensure there is no jumper on JU10 (FLTDLY). This enables the safety circuitry. 10) Attach differential sources to SMA connectors J11 and J12. Each source should have peak-to-peak amplitude between 100mV and 830mV. 11) Apply either +3.3V or +5V power to the board at the J8 (VCC) and J9 (GND) test points. Put a jumper across pins 1 and 2 of JU2. Set the current limit to 300mA. 12) While monitoring the laser output, adjust R14 (RSET) until the desired laser bias current is obtained. Turning the R14 potentiometer screw counterclockwise increases the laser bias current. _______________________________________________________________________________________ MAX3289 Longwave (Common Anode) Evaluation Kit DESIGNATION NAME JU2 – JU10 FLTDLY FUNCTION Placing a jumper between pins 1 and 2 of JU2 applies power to the upper prestuffed circuit. Placing a jumper between pins 2 and 3 of JU2 applies power to the lower unstuffed circuit. Placing a jumper on JU10 disables the laser driver safety features. R7 RTC Potentiometer R7, in conjunction with potentiometer R8 (RMOD), sets the temperature coefficient of the laser modulation current. Turn the potentiometer screw counterclockwise to increase resistance. The temperature coefficient decreases when the potentiometer screw turns counterclockwise. R8 RMOD Potentiometer R8, in conjunction with potentiometer R7 (RTC), sets the peak-to-peak amplitude of the laser modulation current. Turn the potentiometer screw counterclockwise to increase resistance. The laser modulation current amplitude decreases when the potentiometer screws turn counterclockwise. R14 RSET Potentiometer R14 adjusts the desired laser DC-current bias point. Potentiometer R14 sets the resistance from MD to ground. MD regulates to 1.77V. Turn the potentiometer screw clockwise to increase resistance. The total range is 0 to 100kΩ. The laser average power increases when the potentiometer screws turn counterclockwise. SP9, SP10 – Short across these shunts with a bridge of solder when performing electrical evaluation. 13) While monitoring the laser output, adjust R8 (RMOD) until the desired modulation current is obtained. Turning the R8 potentiometer screw clockwise increases the laser modulation current. Detailed Description Emulating a Photodiode During Electrical Evaluation When evaluating the MAX3289/MAX3299 without a laser, the IC’s DC bias circuitry operates using a photodiode emulator circuit. When shunts SP9 and SP10 are shorted, U6 (MAX4322), Q7, and R39 form a currentcontrolled current source that emulates the behavior of the photodiode in the laser assembly. R40 takes the place of the laser diode, and the photodiode emulator circuitry sources a current from the collector of Q7 that is a fraction of the current through R40. This simulates the behavior of a laser diode and photodiode assembly where a fraction of the laser light reflects onto the photodiode, which then outputs a small current proportional to the light emitted. 1) Use solder wick to remove as much solder as possible from the MAX3289’s leads. 2) Using a small metal pick, heat each lead and gently lift it from its pad, being careful not to damage the underlying trace. 3) Flip the board over and notice that there is a hole underneath the exposed pad of the MAX3289 in the middle of the thermal pad. Place the tip of a soldering iron into the hole in the thermal pad. The MAX3289 should fall away from the board. 4) Use solder wick to remove any residual solder around the thermal pad. Once the MAX3289 has been removed, the MAX3299 may be mounted. S M A 4 Evaluating the MAX3299 The MAX3289 longwave (common-anode) evaluation kit is shipped with the MAX3289 installed in the circuit. To evaluate the MAX3299, remove the MAX3289 from the board. The MAX3289 comes in an exposed-pad package. The exposed pad is an area of exposed metal lead frame underneath the 16-pin package that is soldered to a copper thermal pad. To remove the MAX3289 follow these steps: 1 3 MAX3289 MAX3299 2 1 = PHOTODIODE ANODE 2, 4 = VCC 3 = LASER-DIODE CATHODE Figure 1. Optical Connection Diagram _______________________________________________________________________________________ 3 Evaluates: MAX3289/MAX3299 Table 1. Adjustment and Control Descriptions 4 RTC VCC J9 14 3 TC FLTDLY 2 MODSET VCC GND 1 VCC C9 0.01µF 5 IN- 4 IN+ Figure 2. MAX3289 EV Kit Schematic _______________________________________________________________________________________ C7 0.01µF U1 11 MAX3289 OUT- VCC 12 10 9 7 J12 R6 115Ω 1% 6 J11 8 GND TP2 13 OUT+ C21 0.01µF 15 L3 C16 0.01µF VCC VCC 1 16 TP11 L6 C15 0.01µF C26 0.01µF 3 2 JU2 1 REF JU10 R8 50k TP12 VCC C24 10µF VCC2 MD BIASDRV 2 R7 100k RMOD C48 0.01µF L7 SHDNDRV FLTDLY GND VCC1 J8 C10 0.01µF R17 24.9Ω C49 0.01µF VCC C50 0.1µF R1 0Ω C18 OPEN TP1 R19 49.9Ω R16 18Ω R27 6.8Ω J16 VCC L2 R15 36Ω Q3 SP10 2 RSET D2 C44 0.01µF 1 3 R14 100k R40 36Ω SP9 C33 0.01µF TP13 3 4 VCC U6 VCC MAX4322 1 Q7 R39 1k Evaluates: MAX3289/MAX3299 MAX3289 Longwave (Common Anode) Evaluation Kit R36 OPEN R31 OPEN VCC2 C39 0.01µF VCC2 VCC2 16 VCC2 15 14 OUT+ VCC VCC 3 FLTDLY 2 MODSET J13 IN- GND C37 0.01µF IN+ 5 9 6 7 J14 8 GND 4 10 VCC R43 115Ω MAX3289 OUT- 1 TC U4 11 REF C36 0.01µF 12 VCC2 MD BIASDRV C35 OPEN 13 R35 24.9Ω C42 0.01µF L10 L11 C41 0.01µF SHDNDRV _______________________________________________________________________________________ C38 0.01µF R34 24.9Ω C51 0.1µF C43 OPEN R33 18Ω R4 36Ω Q5 L1 D5 R2 OPEN C45 0.01µF VCC2 Evaluates: MAX3289/MAX3299 NOTE: EXCEPT FOR U4, ALL COMPONENTS ARE USER SUPPLIED; VALUES ARE FOR REFERENCE ONLY. MAX3289 Longwave (Common Anode) Evaluation Kit Figure 2. MAX3289 EV Kit Schematic (continued) 5 Evaluates: MAX3289/MAX3299 MAX3289 Longwave (Common Anode) Evaluation Kit 1.0" Figure 3. MAX3289 EV Kit Component Placement Guide— Component Side 1.0" Figure 4. MAX3289 EV Kit PC Board Layout—Component Side 6 1.0" Figure 5. MAX3289 EV Kit PC Board Layout—Power Plane _______________________________________________________________________________________ MAX3289 Longwave (Common Anode) Evaluation Kit Evaluates: MAX3289/MAX3299 1.0" 1.0" Figure 6. MAX3289 EV Kit PC Board Layout—Ground Plane Figure 7. MAX3289 EV Kit PC Board Layout—Solder Side _______________________________________________________________________________________ 7 Evaluates: MAX3289/MAX3299 MAX3289 Longwave (Common Anode) Evaluation Kit NOTES 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. 8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.