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| 19-1645; Rev 0; 1/00 MAX3289 Longwave (Common Anode) Evaluation Kit 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. o Drives Common-Anode Lasers o Socket for Laser Insertion o LED Fault Indicator o Evaluates Either MAX3289 (installed) or MAX3299 o Adjustable Laser Bias Current o Adjustable Laser Modulation-Current Temperature Coefficient o Configured for Electrical Operation, No Laser Necessary Features Evaluates: MAX3289/MAX3299 Ordering Information PART MAX3289EVKIT *Exposed Pad TEMP. RANGE 0C to +70C IC PACKAGE 16 TSSOP-EP* Component List DESIGNATION QTY C7, C9, C10, C15, C16, C21, C26, C44, C48, C49 C18 C24 C33 C50 D2 L2 L3, L6 L7 JU2 JU10 J8, J9 TP1, TP2, TP11, TP12, TP13 10 0 1 1 1 0 1 2 1 1 1 2 DESCRIPTION 0.01F, 10V min 10% X7R ceramic capacitors (0402) Open, user supplied (0402)** 10F, 16V 10% tantalum capacitor AVX TAJC106K016 0.01F, 10V min 10% X7R ceramic capacitor (0603) 0.1F, 10V min 10% X7R ceramic capacitor (0603) Open, user supplied (laser diode and photodiode assembly, Figure 1) Ferrite bead, included but not installed Murata BLM11HA102SG Ferrite beads Murata BLM11HA102SG Ferrite bead Murata BLM11HA601SG 3-pin header (0.1in centers) 2-pin header (0.1in centers) Digi-Key S1012-36-ND Test points Mouser 151-203 Test points Mouser 151-203 R8 R15, R40 R16 R17 R19 R27 R39 J11, J12, J16 Q3 Q7 U1 U6 1 2 1 1 1 1 1 3 1 1 2 1 DESIGNATION QTY R1 R6 R7, R14 1 1 2 DESCRIPTION 0 resistor (0402) 115 1% resistor (0402) 100k variable resistors Bourns Digi-Key 3296W-104-ND 50k variable resistor Bourns Digi-Key 3296W-503-ND 36 5% resistors (0603) 18 5% resistor (0402) 24.9 1% (0402)** 49.9 1% resistor (0402) 6.8 1% resistor (0402) 1k 5% resistor (0402) SMA connectors (edgemount) EFJohnson 142-0701-801 or Digi-Key J502-ND Zetex FMMT491A Zetex FMMT591A Installed: MAX3289CUE (16-pin TSSOP-EP); included but not installed: MAX3299CUE (16-pin TSSOP-EP) MAX4322EUK (5-pin SOT23) 5 **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 = 24.9 as a starting point. 1 ________________________________________________________________ Maxim Integrated Products 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. MAX3289 Longwave (Common Anode) Evaluation Kit Evaluates: MAX3289/MAX3299 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 100k range of the multiturn potentiometer). This sets the regulation point for the simulated photodiode current to 1.7V / 50k = 34A. The photodiode emulator circuit regulates the DC bias current into Q3 to 28 * 34A 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 50k 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 100k 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 50 characteristic impedance cable between the J16 SMA output connector and the input of the oscilloscope. Ensure the oscilloscope input is 50 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 100k range of the multiturn potentiometer). This sets the regulation point for the photodiode current to 1.7V / 50k = 34A. 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 34A 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 50k 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 100k range of the multiturn potentiometer). This minimizes the temperature coefficient of the modulation current. 8) Attach a 50 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 Evaluates: MAX3289/MAX3299 Table 1. Adjustment and Control Descriptions DESIGNATION JU2 JU10 R7 NAME - FLTDLY RTC 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. 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. 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. 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 100k. The laser average power increases when the potentiometer screws turn counterclockwise. Short across these shunts with a bridge of solder when performing electrical evaluation. R8 RMOD R14 SP9, SP10 RSET - 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. 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. 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. 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 VCC2 VCC R39 1k VCC R16 18 C44 0.01F R40 36 4 U6 3 MAX4322 1 Q7 R27 6.8 TP13 R1 0 VCC J16 D2 C33 0.01F R19 49.9 TP12 MAX3289 Longwave (Common Anode) Evaluation Kit 4 C24 10F VCC C26 0.01F 3 2 JU2 1 R17 24.9 C15 0.01F VCC C18 OPEN L6 C16 0.01F L2 L3 C49 0.01F TP1 TP11 SP9 SP10 VCC C50 0.1F 16 15 VCC VCC OUTOUT+ MODSET BIASDRV SHDNDRV 14 13 12 11 10 TC 9 VCC1 J8 L7 J9 GND Figure 2. MAX3289 EV Kit Schematic Q3 R15 36 1 RSET 2 R14 100k 3 VCC C48 0.01F RMOD R8 50k RTC R7 100k U1 MAX3289 MD VCC GND REF IN+ IN3 4 5 6 8 7 1 2 FLTDLY GND FLTDLY R6 115 1% TP2 VCC C7 0.01F J12 J11 C9 0.01F C10 0.01F _______________________________________________________________________________________ 2 JU10 C21 0.01F 1 NOTE: EXCEPT FOR U4, ALL COMPONENTS ARE USER SUPPLIED; VALUES ARE FOR REFERENCE ONLY. R33 18 C43 OPEN C41 0.01F R34 24.9 L11 VCC2 VCC2 R35 24.9 VCC2 D5 C39 0.01F C42 0.01F R31 OPEN L1 VCC2 R36 OPEN C45 0.01F Figure 2. MAX3289 EV Kit Schematic (continued) VCC2 L10 16 15 10 BIASDRV SHDNDRV 14 13 12 11 9 C51 0.1F Q5 R4 36 1 C35 OPEN VCC2 C36 0.01F R43 115 R2 OPEN TC VCC VCC OUT- OUT+ MODSET U4 MAX3289 MD VCC GND REF IN+ IN3 4 5 6 8 7 2 FLTDLY GND C37 0.01F C38 0.01F Evaluates: MAX3289/MAX3299 _______________________________________________________________________________________ J13 J14 MAX3289 Longwave (Common Anode) Evaluation Kit 5 MAX3289 Longwave (Common Anode) Evaluation Kit Evaluates: MAX3289/MAX3299 1.0" Figure 3. MAX3289 EV Kit Component Placement Guide-- Component Side 1.0" 1.0" Figure 4. MAX3289 EV Kit PC Board Layout--Component Side Figure 5. MAX3289 EV Kit PC Board Layout--Power Plane 6 _______________________________________________________________________________________ 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 MAX3289 Longwave (Common Anode) Evaluation Kit Evaluates: MAX3289/MAX3299 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 (c) 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. |
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