Maxim MAX3287 User manual

General Description
The MAX3287 shortwave or VCSEL evaluation kit (EV
kit) is an assembled, surface-mount demonstration
board that allows easy optical and electrical evaluation
of the MAX3287/MAX3288 1.25Gbps laser drivers or
the MAX3297/MAX3298 2.5Gbps laser drivers in the
common-cathode configuration. Short-wavelength laser
diodes (wavelength ≤980nm) and vertical cavity-sur-
face emitting lasers (VCSELs) typically require a com-
mon-cathode configuration. In the common-cathode
configuration, the laser’s cathode connects to ground
and the laser is driven at its anode.
When used with the MAX3287/MAX3297, the laser bias
current regulates to keep a constant photodiode cur-
rent (for shortwave laser diodes). When used with the
MAX3288/MAX3298, the laser bias current is directly
sensed and held constant.
This EV kit includes an extra blank circuit without com-
ponents to demonstrate a small, tight layout optimized
for optical evaluation.
Features
♦Drives Common-Cathode Lasers
♦Includes Socket for Laser Insertion
♦Evaluates MAX3287 (installed) or MAX3288/97/98
♦Adjustable DC Bias Current (MAX3288/98)
♦Adjustable Photodiode Current (MAX3287/97)
♦Adjustable Modulation Current
♦Adjustable Modulation-Current Tempco
♦Configured for Electrical Operation, No Laser
Necessary
♦Extra-Small-Size Blank Circuit (for optical
evaluation only)
Evaluates: MAX3287/MAX3288/MAX3297/MAX3298
MAX3287 Shortwave or VCSEL
(Common Cathode) Evaluation Kit
________________________________________________________________ Maxim Integrated Products 1
19-1961; Rev 0; 2/01
Component List
PART
MAX3287EVKIT 0°C to +70°C
TEMP. RANGE IC PACKAGE
16 TSSOP
Ordering Information
2-pin header (0.1in centers)1JU1
SMA connectors (edge mount)
EFJohnson 142-0701-801 or
Digi-Key J502-ND
3J4, J5, J15
Test points
Mouser 151-203
2J1, J2
Open, user supplied (laser diode and
photodiode assembly; Figure 1)
0D1
10µF ±10%, 16V tantalum capacitor
AVX TAJC106K016
1C23
Open, user supplied (0402)*0C12
DESIGNATION
0.1µF ±10%, 10V min, X7R ceramic
capacitor (0603)
1C11
0.01µF ±10%, 10V min, X7R ceramic
capacitors (0402)
9
C1–C4, C13,
C14, C22, C40,
C52
DESCRIPTIONQTY
10kΩvariable resistor
Bourns or Digi-Key 3296W-103-ND
1R5
50kΩvariable resistor
Bourns or Digi-Key 3296W-503-ND
1R4
100kΩvariable resistor
Bourns or Digi-Key 3296W-104-ND
1R3
115Ω±1% resistor (0402)1R2
Zetex FMMT491A1Q6
Zetex FMMT591A1Q2
Open0Q1
Ferrite bead
Murata BLM11HA601SG
1L4
Ferrite bead (included but not installed)
Murata BLM11HA102SG
1L3
5.1kΩ±5% resistor (0402)1R10
1kΩ±5% resistor (0402)1R9
DESIGNATION DESCRIPTIONQTY
3-pin header (0.1in centers)1JU3 200Ωvariable resistor
Bourns or Digi-Key 3296W-201-ND
1R11
Ferrite beads
Murata BLM11HA102SG
2L1, L2
0Ωresistors (0402)2R12, R23
For free samples and the latest literature, visit www.maxim-ic.com or phone [phone].
For small orders, phone [phone].
*See page 2 for note.

Evaluates: MAX3287/MAX3288/MAX3297/MAX3298
MAX3287 Shortwave or VCSEL
(Common Cathode) Evaluation Kit
2 _______________________________________________________________________________________
Electrical Quick Start
Electrical Quick Start with the
MAX3287/MAX3297 and Simulated
Photodiode Feedback
1) Configure the board so that it will servo the DC bias
current, achieving a fixed photodiode current and
activating the photodiode emulator circuit. Set up
the following shunts:
Refer to the MAX3287/MAX3297 common-cathode
laser with photodiode application circuit in the
MAX3286–MAX3289/MAX3296–MAX3299 data sheet.
2) Make sure nothing is installed in the laser socket
(Figure 1).
3) Confirm that R24 is installed.
4) Make sure L3 is not installed.
5) Confirm that C12 is open. Without a laser installed,
no compensation network is necessary.
6) Set potentiometer R5 (RSET) to midscale by turning
the screw counterclockwise until a faint click is felt,
then clockwise for 15 full revolutions (30 full revolu-
tions in the 0 to 10kΩrange of the multiturn poten-
tiometer). This sets the regulation point for the simu-
lated photodiode current to (2.65V - 1.7V) / 5kΩ=
190µA. The photodiode emulator circuit regulates the
DC bias current out of Q2 to (28 ✕190µA) ≈5mA.
7) Set potentiometer R4 (RMOD) to maximum resis-
tance 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 mini-
mizes the modulation current.
8) Set potentiometer R3 (RTC) 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 mini-
mizes the temperature coefficient (tempco) of the
modulation current.
9) Set potentiometer R11 to 30Ωof resistance by turn-
ing the screw clockwise until a faint click is felt,
then counterclockwise five turns.
10) Make sure there is no jumper on JU1 (FLTDLY).
11) Put a jumper between pins 1 and 2 of JU3 to pro-
vide power to the main circuit (instead of to the opti-
mized layout circuit).
12) Attach a cable with 50Ωcharacteristic impedance
between the J15 SMA output connector and the
input of the oscilloscope. Make sure the oscillo-
scope input is 50Ωterminated.
13) Attach differential sources to SMA connectors J4
and J5. Each source should have a peak-to-peak
amplitude between 100mV and 830mV.
14) Apply either +3.3V or +5V power to the board at the
J1 (VCC) and J2 (GND) test points. Set the current
limit to 300mA.
15) While monitoring the voltage across R37 (TP3 to
GND), adjust R5 (RSET) until the desired DC bias
current is obtained. Turning the R5 potentiometer
screw clockwise increases the DC bias current.
16) While monitoring the J15 SMA connector output on
the oscilloscope, adjust R4 (RMODSET) until the
desired modulation current is obtained. Turning the
R4 potentiometer screw clockwise increases the
modulation current.
SHUNT STATUS
SP1 Closed
SP2 Closed
24.9Ω±1% resistor (0402)*1R13
MAX4322EUK (5-pin SOT23)1U5
MAX3298CUE (16-pin TSSOP-EP,
included but not installed)
2U2, U3
DESIGNATION
MAX3297CUE (16-pin TSSOP-EP,
included but not installed)
2U2, U3
MAX3288CUE (16-pin TSSOP-EP,
included but not installed)
2U2, U3
MAX3287CUE (16-pin TSSOP-EP)2U2, U3
DESCRIPTIONQTY
Test points
Mouser 151-203
6
TP1, TP2, TP3,
TP9, TP10
36Ω±5% resistor (0603)1R37
24.9Ω±1% resistor (0402)0R24
49.9Ω±1% resistor (0402)1R20
Component List (continued)
*These components are part of the compensation network,
which reduces overshoot and ringing. Parasitic series induc-
tance introduces a zero into the laser’s frequency response.
R13 and C12 add a pole to cancel this zero. The optimal val-
ues depend upon the laser used. Maxim recommends R13 =
24.9Ωand C12 = 2pF as a starting point.
SP3 Open
SP4 Closed
SP7
SP5 Closed
Open
SP6 Closed
SP8 Open
1kΩ±5% resistor (0402)1R38

Electrical Quick Start with the
MAX3288/MAX3298 and Bias-Current
Feedback (VCSEL)
1) Configure the board to directly regulate the DC bias
current. Set up the following shunts:
Refer to the MAX3288/MAX3298 common-cathode
laser without photodiode application circuit in the
MAX3286–MAX3289/MAX3296–MAX3299 data
sheet.
2 Make sure nothing is installed in the laser socket
(Figure 1).
3) Confirm that R24 is installed.
4) Make sure L3 is not installed.
5) Confirm that C12 is open. Without a laser installed,
no compensation network is necessary.
6) Set the R11 potentiometer to midscale by turning
the screw counterclockwise until a faint click is felt,
then clockwise for 15 full revolutions (30 full revolu-
tions in the 0 to 200Ωrange of the multiturn poten-
tiometer). This sets the regulation point for the laser
bias current to 0.25V / 100Ω= 2.5mA.
7) Set potentiometer R4 (RMOD) to maximum resis-
tance 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 mini-
mizes the modulation current.
8) Set potentiometer R3 (RTC) 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 mini-
mizes the tempco of the modulation current.
9) Make sure there is no jumper on JU1 (FLTDLY).
10) Put a jumper between pins 1 and 2 of JU3 to pro-
vide power to the main circuit (instead of to the
optimized layout circuit).
11) Attach a 50Ωcharacteristic impedance cable
between the J15 SMA output connector and the
input of the oscilloscope. Make sure the oscillo-
scope input is 50Ωterminated.
12) Attach differential sources to SMA connectors J4
and J5. Each source should have a peak-to-peak
amplitude between 100mV and 830mV.
13) Apply either +3.3V or +5V power to the board at the
J1 (VCC) and J2 (GND) test points. Set the current
limit to 300mA.
14) While monitoring the voltage between TP3 and
GND, adjust R11 until the desired DC bias current
is obtained. Turning the R11 potentiometer screw
clockwise increases the DC bias current.
15) While monitoring the J15 SMA connector output on
the oscilloscope, adjust R4 (RMOD) until the desired
modulation current is obtained. Turning the R4
potentiometer screw clockwise increases the mod-
ulation current.
Emulating a Photodiode
During Electrical Evaluation
When evaluating the MAX3287/MAX3297 without a
laser (see Electrical Quick Start with the MAX3287/
MAX3297 and Simulated Photodiode Feedback), the
MAX3287/MAX3297 DC bias circuitry operates using a
photodiode emulator circuit. When shunts SP1 and SP2
are shorted, U5 (MAX4322), Q6 (FMMT491A), and R38
form a current-controlled current source that emulates
the behavior of the photodiode in the laser assembly.
R37 takes the place of the laser diode, and the photodi-
ode emulator circuitry sinks a current from the collector
of Q6 equal to 3% of the current through R37. This sim-
Evaluates: MAX3287/MAX3288/MAX3297/MAX3298
MAX3287 Shortwave or VCSEL
(Common Cathode) Evaluation Kit
_______________________________________________________________________________________ 3
SHUNT STATUS
SP3
SP1 Open
Closed
SP2 Closed
SP4 Open
SP7
SP5 Closed
Closed
SP6 Open
SP8 Closed
2 = LASER-DIODE ANODE
4 = PHOTODIODE CATHODE
1, 3 = GROUND (LASER-DIODE CATHODE/PHOTODIODE ANODE)
S
M
A
MAX3287
MAX3288
MAX3297
MAX3298
21
34
Figure 1. Optical Connection Diagram

ulates 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 pro-
portional to the light emitted.
Optical Quick Start
Optical Quick Start with the
MAX3287/MAX3297 and Photodiode
Feedback
1) Configure the board so that it will servo the laser
bias current, achieving a fixed photodiode current.
Set up the following shunts:
Refer to the MAX3287/MAX3297 common-cathode
laser with photodiode applications circuit in the
MAX3286–MAX3289/MAX3296–MAX3299 data
sheet.
2) Remove R24.
3) Install L3.
4) Connect a laser to the board (Figure 1).
5) Set the R5 (RSET) potentiometer to midscale by
turning the screw counterclockwise until a faint
click is felt, then clockwise for 15 full revolutions (30
full revolutions in the 0 to 10kΩrange of the multi-
turn potentiometer). This sets the regulation point
for the photodiode current to (2.65V - 1.7V) / 5kΩ=
190µA.
6) Set potentiometer R4 (RMOD) to maximum resis-
tance 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 mini-
mizes the modulation current (AC drive applied to
laser).
7) Set potentiometer R3 (RTC) 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 mini-
mizes the tempco of the modulation current.
8) Set potentiometer R11 to 30Ωof resistance by turn-
ing the screw clockwise until a faint click is felt,
then counterclockwise five turns.
9) Attach a 50ΩSMA terminator to J15 to match the
laser loading.
10) Make sure there is no jumper on JU1 (FLTDLY).
11) Put a jumper between pins 1 and 2 of JU3 to pro-
vide power to the main circuit (instead of to the
optimized layout circuit).
12) Attach differential sources to SMA connectors J4
and J5. Each source should have a peak-to-peak
amplitude between 100mV and 830mV.
13) Apply either +3.3V or +5V power to the board at the
J1 (VCC) and J2 (GND) test points.
14) While monitoring the laser output, adjust R5 (RSET)
until the desired laser bias current is obtained.
Turning the R5 potentiometer screw clockwise
increases the laser bias current.
15) While monitoring the laser output, adjust R4 (RMOD)
until the desired laser modulation current is
obtained. Turning the R4 potentiometer screw
clockwise increases the laser modulation current.
16) Look at the “eye” output on the oscilloscope. Laser
overshoot and ringing can be improved by appro-
priate selection of R13 and C12, as described in
the Designing the Laser-Compensation Filter
Network section of the MAX3286–MAX3289/
MAX3296–MAX3299 data sheet.
Optical Quick Start with the MAX3288/
MAX3298 and Bias-Current Feedback
(VCSELs)
1) Configure the board to directly regulate the laser
bias current. Set up the following shunts:
Refer to the MAX3288/MAX3298 common-cathode
laser without photodiode applications circuit in the
MAX3286–MAX3289/MAX3296–MAX3299 data
sheet.
Evaluates: MAX3287/MAX3288/MAX3297/MAX3298
MAX3287 Shortwave or VCSEL
(Common Cathode) Evaluation Kit
4 _______________________________________________________________________________________
SHUNT STATUS
SP3
SP1 Open
Closed
SP2 Open
SP4 Open
SP7
SP5 Closed
Closed
SP6 Open
SP8 Closed
SHUNT STATUS
SP3
SP1 Open
Open
SP2 Open
SP4 Closed
SP7
SP5 Closed
Open
SP6 Closed
SP8 Open

Evaluates: MAX3287/MAX3288/MAX3297/MAX3298
MAX3287 Shortwave or VCSEL
(Common Cathode) Evaluation Kit
_______________________________________________________________________________________ 5
2) Remove R24
3) Install L3.
4) Connect a laser to the board (Figure 1).
5) Set potentiometer R11 to midscale by turning the
screw counterclockwise until a faint click is felt,
then clockwise for 15 full revolutions (30 full revolu-
tions in the 0 to 200Ωrange of the multiturn poten-
tiometer). This sets the regulation point for the laser
bias current to 0.25V / 100Ω= 2.5mA.
6) Set potentiometer R4 (RMOD) to maximum resis-
tance 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 mini-
mizes the modulation current.
7) Set potentiometer R3 (RTC) 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 mini-
mizes the tempco of the modulation current.
8) Attach a 50ΩSMA terminator to J15 to match the
laser loading.
9) Make sure there is no jumper on JU1 (FLTDLY).
10) Put a jumper between pins 1 and 2 of JU3 to pro-
vide power to the main circuit (instead of to the
optimized layout circuit).
11) Attach differential sources to SMA connectors J4
and J5. Each source should have a peak-to-peak
amplitude between 100mV and 830mV.
12) Apply either +3.3V or +5V power to the board at the
J1 (VCC) and J2 (GND) test points. Set the current
limit to 300mA.
13) While monitoring the laser output, adjust R11 until
the desired DC bias current is obtained. Turning
the R11 potentiometer screw clockwise increases
the DC bias current.
14) While monitoring the laser output, adjust R4
(RMOD) until the desired modulation current is
obtained. Turning the R4 potentiometer screw
clockwise increases the modulation current.
15) Look at the “eye” output on the oscilloscope. Laser
overshoot and ringing can be improved by appro-
priate selection of R13 and C12 as described in the
Designing the Laser-Compensation Filter Network
section of the MAX3286–MAX3289/MAX3296–
MAX3299 data sheet.
Detailed Description
Evaluating the MAX3288/MAX3297/MAX3298
The MAX3287 EV kit ships with the MAX3287 installed
in the circuit, but the board can be modified to accom-
modate the MAX3288, MAX3297, or MAX3298. The
MAX3287 comes in an exposed-paddle package. The
exposed paddle is an area of exposed metal leadframe
underneath the 16-pin package that is soldered to a
copper thermal pad. To evaluate the MAX3288/
MAX3297/MAX3298, first follow these steps to remove
the MAX3287 from the board:
1) Use a solder wick to remove as much solder as
possible from the leads on the MAX3287.
2) Using a small metal pick, heat each lead, and gen-
tly 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 paddle of the MAX3287 in
the middle of the thermal pad. Place the tip of a sol-
dering iron into the hole in the thermal pad; the
MAX3287 should fall away from the board.
4) Use the solder wick to remove any residual solder
around the thermal pad.
Once the MAX3287 has been removed, any of the other
three ICs may be mounted on the board.

Evaluates: MAX3287/MAX3288/MAX3297/MAX3298
MAX3287 Shortwave or VCSEL
(Common Cathode) Evaluation Kit
6 _______________________________________________________________________________________
8
7
6
5
4
3
2
1
9
J15
R23
0Ω
R20 49.9Ω
R4
50k
RMOD
R3
100k
RTC
VCC
VCC2
L4
J1 J2 VCC
VCC1
GND
FLTDLY
JU1
VCC
VCC2
VCC2
TP1
C22
0.01µF
C1
0.01µFC4
0.01µF
C3 0.01µF
C17
0.01µF
C8
0.01µF
C6
0.01µF
R26
24.9Ω
C30
0.01µF
C31
0.01µF
VCC2
R30
115Ω
R29
OPEN
R22 OPEN
R25 OPEN
C32
0.01µF
C29 0.01µF
J7 J6
L5
L8
R2
115Ω 1%
VCC
VCC VCC
L1
TP10
OUT-
TP9
L2
L3
C40
0.01µF
C13 0.01µF
C14 0.01µF
C12 OPEN R13 24.9Ω
R11
200Ω
RMON
R38
1k R37
36Ω
TP3
SP8
RSET
SP6 SP7 R10
5.1k
R9
1k
R5
10k
C25 OPEN
R27 24.9Ω
R1 36Ω
C28 0.01µF
Q4
L9
D3
C27
0.1µF
VCC2
VCC2
VCC2
R42
0Ω
SP4
3
Q2
SP5
SP3
D1
3 4
1
Q1
Q6
SP1
1
1 3
2
2
R24 24.9Ω
R12
0Ω
TP2
C2
0.01µF
C52
0.01µF
C23
10µF
C11
0.1µF
10
11
12
13
14
15
16
123
MD
REF
GND
IN-
IN+
VCC
FLTDLY
GND
SHDNDRV
BIASDRV
VCC
OUT+
OUT-
VCC
MODSET
TC
MD
REF
GND
IN-
IN+
VCC
FLTDLY
GND
8
7
6
5
4
3
2
1
9
10
11
12
13
14
15
16
SHDNDRV
BIASDRV
VCC
OUT+
OUT-
VCC
MODSET
TC
MAX3287
U3
MAX3287
U2
SP2
U5
MAX4322
JU3
NOTE: THE CIRCUIT ENCLOSED IN DOTTED LINES IS A BLANK, UNSTUFFED LAYOUT ON THE MAX3287 EV KIT BOARD.
J4 J5
Figure 2. MAX3287 EV Kit Schematic

Evaluates: MAX3287/MAX3288/MAX3297/MAX3298
MAX3287 Shortwave or VCSEL
(Common Cathode) Evaluation Kit
_______________________________________________________________________________________ 7
Table 1. Adjustment and Control Descriptions
COMPONENT NAME
R4
JU1 FLTDLY
RMOD
R3 RTC
R5 RSET
R11 RMOD
FUNCTION
Placing a jumper on JU1 disables the laser-driver safety features.
Potentiometer R4, in conjunction with potentiometer R3 (RTC), sets the peak-to-peak amplitude
of the laser modulation current. Turn the potentiometer screw counterclockwise to increase the
resistance. The laser modulation-current amplitude decreases when the potentiometer screw
turns counterclockwise.
Potentiometer R3, in conjunction with potentiometer R4 (RMOD), sets the tempco of the laser mod-
ulation current. Turn the potentiometer screw counterclockwise to increase the resistance. The
tempco decreases when the potentiometer screw turns counterclockwise.
Potentiometer R5 adjusts the desired laser DC-current bias point. Potentiometer R5 sets the resis-
tance from MD to ground, and MD regulates to 1.7V. Turn the potentiometer screw clockwise to
decrease the resistance. The total range is 0 to 10kΩ. The laser average power increases when
the potentiometer screw turns clockwise.
R11 adjusts the amount of degeneration in the bias transistor when using a photodiode. When
directly sensing bias current, R11 sets the regulation point.
Figure 3. MAX3287 EV Kit Component Placement Guide
1.0"
Figure 4. MAX3287 EV Kit PC Board Layout—Component Side
1.0"

8_____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Evaluates: MAX3287/MAX3288/MAX3297/MAX3298
MAX3287 Shortwave or VCSEL
(Common Cathode) Evaluation Kit
1.0"
1.0"
Figure 6. MAX3287 EV Kit PC Board Layout—Ground Plane
Figure 7. MAX3287 EV Kit PC Board Layout—Power Plane
Figure 5. MAX3287 EV Kit PC Board Layout—Solder Side
1.0"
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