19-2787; Rev 0; 2/03
MAX3940 Evaluation Kit
_________________General Description
The MAX3940 evaluation kit (EV kit) is an assembled
demonstration board that provides electrical evaluation of
the MAX3940 10.7Gbps laser driver. The output of the
electrical evaluation section is interfaced to an SMA
connector that can be connected to a 50Ω terminated
oscilloscope.
_____________________________Features
♦
♦
♦
♦
SMA Connectors for All High-Speed I/Os
Configured for Electrical Operation, No Laser
Necessary
Single –5.2V Power-Supply Operation
Fully Assembled and Tested
Evaluates: MAX3940
_____________________ Component List
DESIGNATION
C0, C1,
C10, C11
C2, C6
QTY
4
DESCRIPTION
0.01µF
±10%
ceramic capacitors
(0402)
30pF chip MIS capacitors
Metelics Corporation,
30 mils
×
30mils,
MC2-S-030-020-020
22µF
±10%
tantalum capacitor
AVX TAJB226K010
10µF
±10%
tantalum capacitor
AVX TAJA106K010
0.1µF
±10%
ceramic capacitor
(0402) Murata
GRP155R61A104K
SMA connectors, edge mount,
EF Johnson 142-0701-851
Test points, Digi-Key 5000K-ND
SMB connectors, PC mount
2-pin headers, 0.1in centers
Digi-Key S1012-36-ND
3-pin headers, 0.1in centers
Digi-Key S1012-36-ND
Shunts, Digi-Key S9000-ND
47nH inductor (0402)
2kΩ variable resistors
Bourns 3296W-202
4.2kΩ
±1%
resistor (0402)
2kΩ
±1%
resistor (0402)
Not installed
MAX3940E/D die
MAX3940 EV kit circuit board,
rev A
MAX3940 EV kit data sheet
MAX3940 data sheet
________________Ordering Information
PART
MAX3940EVKIT
TEMP. RANGE
-40°C to +85°C
IC PACKAGE
Chip on board
2
_______________ Component Suppliers
SUPPLIER
AVX
Coilcraft
Digi-Key
EF Johnson
Murata
PHONE
843-444-2863
847-639-6400
218-681-6674
402-474-4800
415-964-6321
FAX
843-626-3123
847-639-1469
218-681-3380
402-474-4858
415-964-8165
C3
C4
C5
J1-J7
J10, J11, TP1
J12, J13
JU1-JU3,
JU5, JU8
JU4, JU6, JU7
JU1- JU8
L0
R0-R2
R3
R4
R5
U1
None
None
None
1
1
1
7
3
2
5
3
8
1
3
1
1
1
1
1
1
1
Note:
Please indicate that you are using the MAX3940 when
ordering from these suppliers.
________________ Detailed Description
The MAX3940 EV Kit is a fully assembled and factory
tested demonstration board that enables testing of all
MAX3940 functions.
•
-5.2V power supply with 300mA current capability
•
Signal-source, 10Gbps minimum capability
•
Oscilloscope with at least 15GHz performance
Test Equipment Required
Test Equipment Interface
The data and clock inputs (DATA±, CLK±) are DC-coupled
to the SMA connectors, so be sure to set proper common-
mode voltages for these inputs. The combination bias and
modulation output (OUT) is also DC-coupled to the SMA
connector and requires a 50Ω to ground load for proper
operation.
__________________________________________________________________Maxim
Integrated Products
1
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.
MAX3940 Evaluation Kit
Evaluates: MAX3940
_____________________________________________________________________ Quick Start
1) If the data is to be latched, place shunt on JU2
(RTEN) to enable the clock inputs. Otherwise, leave
JU2 open.
2) Install jumpers on JU5 and JU8.
3) Install a jumper on the left “DC” side of JU6. This
allows adjustment of MODSET.
4) Install a jumper on the right “DC” side of JU7. This
allows adjustment of BIASSET.
5) To use the pulse-width control (PWC) install a jumper
on the right side of JU4. To disable PWC place a
jumper on the left “GND” side of JU4.
6) Ensure that a jumper is not installed on JU3 to float
MODEN
and enable modulation.
7) Adjust R1 to the full counter-clockwise position. This
will minimize modulation swing.
8) Adjust R2 to the full clockwise position.
minimize bias voltage.
This will
10) Connect a differential signal source to J2 (DATA+)
and J3 (DATA-). Refer to the MAX3940 data sheet to
determine voltage levels.
11) If the latch is enabled, apply a differential clock signal
to J4 (CLK+) and J5 (CLK-). Refer to the MAX3940
data sheet to determine voltage levels.
12) Connect a high-bandwidth oscilloscope such as the
Tektronix CSA8000 with the 80E01 sampling head to
J1 (OUT).
13) A high-quality SMA attenuator (14dB or 20dB) is
required to reduce the signal level for compatibility
with the sampling head. The attenuator should be
connected directly to the output SMA connector on
the EV kit to minimize transmission line reflections.
14) Attach a –5.2V power supply to V
EE
and GND. Set
the current limit to 300mA and power up the board.
15) Adjust R1 clockwise until the desired modulation
swing is achieved.
16) Adjust R2 counter-clockwise until the desired bias
voltage is achieved.
17) Adjust R0 until the desired pulse width is achieved (if
PWC is enabled).
9) Adjust R0 to the approximate center of its adjustment
range (if PWC is enabled).
_______________________________________ Adjustments and Control Descriptions
COMPONENT
JU1
JU2
JU3
R1
R2
R0
NAME
PLRT
RTEN
MODEN
R
MODSET
R
BIASSET
R
PWC
FUNCTION
Enables/disables the polarity inversion function. Shunt JU1 to invert the polarity of the
output data. Shunting JU1 shorts the PLRT pin to V
EE
. Leave open for normal operation.
Enables/disables data retiming. Shunt to enable data retiming. Remove shunt for direct
data transmission.
Enables/disables modulation output. Shunt to disable switching of the data output. When
shunted the output goes to the absorbtive (logic 0) state. Remove shunt to enable
modulation.
Adjusts the EAM modulation current. Turn the potentiometer screw clockwise to increase
the modulation amplitude (decrease the resistance of MODSET to GND).
Adjusts the EAM bias current. Turn the potentiometer screw counter-clockwise to increase
bias current (decrease the resistance from BIASSET to GND).
Adjusts the EAM pulse width. Turn the potentiometer screw clockwise to increase the logic
1 width.
2
__________________________________________________________________________________________________
MAX3940 Evaluation Kit
Evaluates: MAX3940
Figure 1. MAX3940 EV Kit Schematic
_________________________________________________________________________________________________
3
MAX3940 Evaluation Kit
Evaluates: MAX3940
Figure 2. MAX3940 EV Kit Component Placement Guide—Component Side
Figure 3. MAX3940 EV Kit PC Board Layout—Ground Plane
4
__________________________________________________________________________________________________
MAX3940 Evaluation Kit
Evaluates: MAX3940
Figure 4. MAX3940 EV Kit PC Board Layout—Component Side
Figure 5. MAX3872/MAX3874 EV Kit PC Board Layout—Power Plane
_________________________________________________________________________________________________
5
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