__________________________________________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.
Evaluates: MAX3738
MAX3738 Evaluation Kit
_______________
______________________________
_______________ General Description
The MAX3738 evaluation kit (EV kit) is an assembled
demonstration board that provides complete optical and
electrical evaluation of the MAX3738.
The EV kit is composed of two independent sections, one
optical and one electrical, on the PC board. The output of
the electrical evaluation section is interfaced to an SMP
connector that can be connected to a 50Ω terminated
oscilloscope. The output of the optical evaluation section
is configured for attachment to a laser/monitor diode.
________________________ Features
Fully Assembled and Tested
Single +3.3V Power Supply Operation
AC-Coupling Provided On-Board
Allows Optical and Electrical Evaluation
_______________Ordering Information
PART TEMP RANGE IC-PACKAGE
MAX3738EVKIT -40°C to +85°C 24 Thin QFN
________________________________________Electrical Evaluation Component List
DESIGNATION QTY DESCRIPTION
C1, C2, C17,
C19,
C39, C41
60.1µF ±10% ceramic
capacitors (0402)
C3, C6, C14,
C16 40.01µF ±10% ceramic
capacitors (0402)
C7, C9, C11,
C32 40.01µF ±10% ceramic
capacitors (0201)
C10 1 0.5pF ±10% ceramic
capacitor (0201)
C4, C5, C12 3 470pF ±10% ceramic
capacitors (0402)
C18, C36 1 10µF ±10% tantalum
capacitor, case B
J7 1 SMP connector,
Tensolite P698-2CC
J1, J2 2 SMA connectors, round,
Johnson 142-0701-801
JU1, JU8, JU11,
JU14, JU15,
JU17-JU19
8 2-pin headers, 0.1in centers
JU12, JU13 2 4-pin headers, 0.1in centers
JU3-JU5 3 3-pin headers, 0.1in centers
J8, J13, J14,
TP2-TP4, TP6,
TP7, TP9,
TP10, TP12,
TP14-TP17
15 Test Points
DESIGNATION QTY DESCRIPTION
L2, L5 2 1.0µH inductor (1008LS)
Coilcraft 1008CS-122XKBC
Q3 1 MOSFET (SOT23)
Fairchild FDN306P
Q1 1 NPN transistor (SOT23)
Zetex FMMT491A
Q2 1 PNP transistor (SOT23)
Zetex FMMT591A
D1 1 LED, red T1 package
R23-R25, R28-
R34, R41, R42,
R49
— Not installed
R11 1 4.99Ω ±1% resistor (0402)
R12, R13, R14 3 30.1Ω ±1% resistors (0402)
R50 1 75Ω ±1% resistor (0402)
R18 1 392Ω ±1% resistor (0402)
R10 1 511Ω ±1% resistor (0402)
R58 1 332Ω ±1% resistor (0402)
R61 1 3.32kΩ ±1% resistor (0402)
R8, R9 1 4.7kΩ ±1% resistor (0402)
R1-R3, R5, R6 5 100Ω ±1% resistor (0402)
R26 1 20kΩ Variable Resistor
(3296W)
R4, R7, R27 3 50kΩ Variable Resistor
(3296W)
19-3193; Rev 0, 2/04
MAX3738 Evaluation Kit
2 _________________________________________________________________________________________
Evaluates: MAX373
8
_______________________________Electrical Evaluation Component List (cont.)
DESIGNATION QTY DESCRIPTION
U2 1 MAX495ESA (8 SO)
U3 1 MAX3738ETJ
(24 Thin QFN)
None 7 Shunts
None 1 MAX3738 EV board
None 1 MAX3738 data Sheet
_________________________________________Optical Evaluation Component List
DESIGNATION QTY DESCRIPTION
C23, C25, C28,
C30, C31, C33,
C40
70.01µF ±10% ceramic
capacitors (0402)
C26, C29 2 0.01µF ±10% ceramic
capacitors (0603)
C24* 1 8.2pF ±10% ceramic
capacitor (0402)
C27, C34, C35 3 470pF ±10% ceramic
capacitors (0402)
C20, C22, C37,
C38 40.1µF ±10% ceramic
capacitors (0402)
C21 1 10µF ±10% tantalum
capacitor, case B
D3 — Open, user-supplied laser
D4 1 LED, red T1 package
J4, J5 2 SMA connectors, round,
Johnson 142-0701-801
JU16, JU20,
JU30 3 2-pin headers, 0.1in centers
L4 1 Ferrite bead (0603)
Murata BLM18GA601SN1
L3 1 1.0µH inductor (1008CS)
Coilcraft 1008CS-122XKBC
Q4 1 MOSFET (SOT23)
Fairchild FDN306P
Q6 1 NPN transistor (SOT23)
Zetex FMMT491A
*These components are part of the compensation network, which can reduce overshoot and ringing. Ringing due to
parasitic series inductance of the laser may be eliminated with R39 and C24. Starting values for most coaxial lasers is
R39 = 49.9Ω in series with C24 = 8.2pF. These values should be experimentally adjusted until the output waveform is
optimised.
______________ Component Suppliers
Note: Please indicate that you are using the MAX3738 when
contacting these component suppliers.
DESIGNATION QTY DESCRIPTION
R35-R38, R40,
R43-R47 — Not installed
R39*, R48 1 49.9Ω ±1% resistor (0402)
R54 1 10Ω ±1% resistor (0402)
R56 1 15Ω ±1% resistor (0402)
R59 1 511Ω ±1% resistor (0402)
R60 1 4.7kΩ ±1% resistor (0402)
R62 1 3.32kΩ ±5% resistor
(0402)
R65 1 332Ω ±5% resistor (0402)
R63, R64, R68 3 100Ω ±5% resistor (0402)
R51-R53 — Not installed
R55 1 20kΩ variable resistors
Bourns 3296W
R57 1 50kΩ variable resistors
Bourns 3296W
U4 1 MAX3738EGJ (32 QFN)
J3, J6, TP1, TP5,
TP8, TP11, TP13,
TP19, TP20,
TP25-TPT27
12 Test points
None 1 Shunt
None 1 MAX3738 EV board
None 1 MAX3738 data sheet
SUPPLIER PHONE FAX
AVX 803-946-0690 803-626-3123
Coilcraft 847-639-6400 847-639-1469
Murata 814-237-1431 814-238-0490
Zetex 516-543-7100 516-864-7630
MAX3738 Evaluation Kit
________________________________________________________ 3
Evaluates: MAX3738
__________________________Quick Start
Electrical Evaluation
In the electrical configuration, an automatic power control
(APC) test circuit is included to emulate a semiconductor
laser with a monitor photodiode. Monitor diode current is
provided by transistor Q2, which is controlled by an
operational amplifier (U2). The APC test circuit consisting
of U2 and Q2 applies the simulated monitor diode current
(the DC laser current divided by a factor of 80) to the MD
pin of the MAX3738.
1) Place shunts on JU1, JU3, JU4, JU5, JU12, JU13,
and JU19 (Refer to Table 1 for details).
2) If the EV kit is to be used without the optional
shutdown transistor (Q3), place a shunt on JU11.
3) Remove the shunt from JU15 to use the filter
inductor.
4) Connect TX_DISABLE to GND with JU1 to enable
the outputs.
5) Standard electrical tests have bias and modulation
current separated. Check that R11 (between TP6
and TP7) is installed.
Note: When performing the following resistance
checks, manually set the ohmmeter to a high range
to avoid forward biasing the on-chip ESD protection
diodes.
6) Adjust R27, the RMODSET potentiometer, for 25kΩ
resistance between TP10 and ground.
7) Adjust R26, the RAPCSET potentiometer, for 25kΩ
resistance between TP9 and ground.
8) Adjust R4, the RPC_MON potentiometer, to set the
maximum monitor diode current (IMDMAX, see below).
RPC_MON can be measured from TP1 to ground.
Connect the RPC_MON using JU3.
MDMAX
REF
PC_MON I
V
R=
9) Adjust R7, the RBC_MON potentiometer, to set the
maximum bias current (IBIASMAX, see below). RBC_MON
can be measured from TP2 to ground. Connect the
RBC_MON using JU4.
BIASMAX
REF
BC_MON I
V80
R×
=
10) Apply a 2.7Gbps differential input signal (200mVP-P to
2400mVP-P) between SMA connectors J1 and J2 (IN+
and IN-).
11) Attach a high-speed oscilloscope with a 50Ω input to
the SMP connector J7 (OUT+).
Note: J7 has a DC voltage of approximately VCC/2
and can have voltage swings greater than 1V. An
attenuator might be needed to make the signal
compatible with the oscilloscope.
12) Connect a +3.3V supply between VCC and GND
Adjust the power supply until the voltage between
TP12 and ground is +3.3V.
13) Adjust R25 (RAPCSET) until the desired laser bias
current is achieved.
4.9Ω
V-V
ITP6TP7
BIAS =
14) The MD and BIAS currents can be monitored at TP2
(VPC_MON) and TP3 (VBC_MON) using the equation
below:
PC_MON
PC_MON
MD R
V
I=
BC_MON
BC_MON
BIAS R
V80
I×
=
15) Adjust R27 until the desired laser modulation current
is achieved. Measure IMOD with the oscilloscope at J7
by;
15Ω
)(V Amplitude Signal
IP-P
MOD =
Optical Evaluation
For optical evaluation of the MAX3738, configure the
evaluation kit as follows:
1) Remove shunt JU16 to use the filter inductor.
2) If the EV kit is to be used without the optional
shutdown transistor (Q4), place a shunt on JU20.
3) To enable the outputs, connect TX_DISABLE to GND
by placing a shunt on JU30.
4) The EV kit is designed to allow connection of a
variety of possible laser/monitor diode pin
configurations. Connect a TO-header style laser with
monitor diode (Figure 1) as follows:
MAX3738 Evaluation Kit
4 _________________________________________________________________________________________
Evaluates: MAX373
8
• Keeping its leads as short as possible, connect
the laser diode to two of the three pads in the
cutout portion on the top (component) side of the
PC board. Solder the laser diode cathode to the
center pad, and solder the anode to either of the
other two pads (they are both connected to VCC
through the shutdown transistor (Q4)).
• Connect the monitor photodiode to two of the
five pads on the bottom (solder) side of the PC
board, directly below the laser diode pads.
Connect the anode and cathode of the
photodiode as shown in figure 1.
Note: When performing the following resistance
checks, manually set the ohmmeter to a high range
to avoid forward biasing the on-chip ESD protection
diodes.
5) Adjust R57, the RMODSET potentiometer, for maximum
resistance (≈50kΩ) between TP19 and ground. This
sets the modulation current to a low value (<10mA).
(Refer to the Design Procedure section of the
MAX3738 data sheet.)
6) Adjust R55, the RAPCSET potentiometer, for maximum
resistance (≈50kΩ) between TP20 and ground. This
sets the photodiode current to a low value (<18µA).
(Refer to the Design Procedure section of the
MAX3738 data sheet.)
WARNING: Consult your laser data sheet to ensure
that 18µA of photodiode current and 10mA of
modulation current does not correspond to excessive
laser power.
7) Install R64, the RPC_MON resistor, to set the maximum
monitor diode current (IMDMAX, see below).
MDMAX
REF
PC_MON I
V
R=
8) Install R63, the RBC_MON resistor, to set the maximum
bias current (IBIASMAX, see below).
BIASMAX
REF
BC_MON I
V08
R×
=
9) Apply a 2.7Gbps differential input signal (200mVP-P to
2400mVP-P) between SMA connectors J5 and J4 (IN+
and IN-).
10) Attach the laser diode fiber connector to an
optical/electrical converter.
11) Connect a +3.3V supply between J3 (VCC) and J6
(GND). Adjust the power supply until the voltage
between TP15 and ground is +3.3V.
12) Adjust R55 (RAPCSET) until the desired average optical
power is achieved.
13) The MD, MOD and BIAS currents can be monitored
at TP27 (VPC_MON) and TP26 (VBC_MON) using the
equations below:
PC_MON
PC_MON
MD R
V
I=
BC_MON
BC_MON
BIAS R
V08
I×
=
Note: If the voltage at TP26 or TP27 exceeds 1.38V,
the TX_FAULT signal will be asserted and latched.
14) Adjust R57 (RMODSET) until the desired optical
amplitude is achieved. Optical amplitude can be
observed on an oscilloscope connected to an
optical/electrical converter. Laser overshoot and
ringing can be improved by appropriate selection of
R39 and C24, as described in the Design Procedure
section of the MAX3738 data sheet.
MAX3738 Evaluation Kit
________________________________________________________ 5
Evaluates: MAX3738
Table 1. Adjustment and Control Descriptions (see Quick Start first)
COMPONENT
OPTICAL ELECTRICAL NAME FUNCTION
D4 D1 Fault
Indicator
LED is illuminated when a fault condition has occurred
(Refer to the Detailed Description section of the
MAX3735 data sheet).
JU16 JU15 —
Placing a shunt on JU15 or JU16 removes the inductor
from the filter networks by shorting the inductor lead
together. Remove shunts for normal operation.
—JU13—
Placing a shunt on JU13 connects the MODSET pin of
the MAX3738 to the RMODSET potentiometer. Select a
fixed resistor value when testing over temperature.
JU30 JU1 TX_DISABLE Enables/disables the output currents. Active low (shunt
across JU1 or JU30 to enable output currents).
—JU12—
Placing a shunt on JU12connects the APCSET pin of
the MAX3738 to the RAPCSET potentiometer. Select a
fixed resistor value when testing over temperature.
JU20 JU11 — Installing a jumper on JU11 or JU20 disables the
optional shutdown transistors.
R40, R57 R27, R29, R30 RMODSET Adjusts the laser modulation current
R45, R55 R23, R24, R26 RAPCSET Adjusts the monitor diode current level to be maintained
by the APC loop
R51, R38 R31, JU14 RMODBCOMP
Sets the K factor compensation of the modulation
current. Leave open to make modulation current
independent of bias current.
R52, R37 R32, JU18 RTH_TEMP Sets the threshold temperature above which modulation
current increases with temperature.
R53, R36 R33, JU17 RMODTCOMP
Sets the temperature coefficient of the modulation
current. Leave open to make modulation current
independent of temperature.
MAX3738 Evaluation Kit
6 _________________________________________________________________________________________
Evaluates: MAX373
8
V
CC
V
CC
R19
V
CC
V
CC
TOP OF PC
BOARD
BOTTOM OF PC
BOARD
SOLDER
BRIDGES
T0-46 CAN
LASER/PHOTODIODE
PAIR
LD
PD
TO MD
CONFIGURATION 1
V
CC
V
CC
R19
V
CC
V
CC
TOP OF PC
BOARD
BOTTOM OF PC
BOARD
SOLDER
BRIDGES
T0-46 CAN
LASER/PHOTODIODE
PAIR
LD
PD
TO MD
CONFIGURATION 2
V
CC
V
CC
R19
V
CC
V
CC
TOP OF PC
BOARD
BOTTOM OF PC
BOARD
SOLDER
BRIDGES
T0-46 CAN
LASER/PHOTODIODE
PAIR
LD
PD
TO MD
CONFIGURATION 3
V
CC
V
CC
R19
V
CC
V
CC
TOP OF PC
BOARD
BOTTOM OF PC
BOARD
SOLDER
BRIDGES
T0-46 CAN
LASER/PHOTODIODE
PAIR
LD
PD
TO MD
CONFIGURATION 4
Figure 1. Attachment of Laser Diode/Monitor Diode to the MAX3738 EV Kit
MAX3738 Evaluation Kit
________________________________________________________ 7
Evaluates: MAX3738
Figure 2. MAX3738 EV Kit Schematic—Electrical Configuration
V
CC
IN+
IN-
V
CC
PC_MON
BC_MON
TX_DISABLE
20
VCC1
U3
MAX3738
V
CC
OUT +
V
CC
BIAS
15
14
R13
30.1
Ω
R50
75
Ω
R
MODSET
SHUT DOWN
7
6
4
2
3
U2
Q2
FM MT 591A
R11
4.99
Ω
MAX 495
R14
30.1
Ω
R12
30.1
Ω
C10
0.5pF
J7
OUT +
OUT -
13JU1
R1
100
Ω
TP9
JU13
R30
OPEN
R58
332
Ω
R61
3.3k
Ω
Q3
FDN306P
SHUT DOWN
JU11
TP7
TP6
R18
392
Ω
MD
TX_FAULT
GND APCFILT1
C11
0.01
µ
F
VCC1 C9
0.01
µ
F
C7
0.01
µ
F
2VCC
C32
0.01
µ
F
C12
470pF
APCFILT2
C16
0.01
µ
F
1922 2124 23
APCSET
MODSET
MODBCOMP
TH_TEMP
MODTCOMP
11 1291078
SHUTDOWN
GND
R29
OPEN
R27
50k
Ω
R
APCSET
JU12
R23
OPEN
R24
OPEN
R26
20k
Ω
R32 OPEN
JU18
R31 OPEN
JU14
R33 OPEN
JU17
C3
0.01
µ
F
C6
0.01
µ
F
VCC1
VCC1
J1
IN+
C1
0.1
µ
F
C2
0.1
µ
F
J2
IN-
VCC1
C14
0.01
µ
F
VCC1
TP4
R9
4.7k
Ω
D1
LED
VCC1
R10
511
Ω
Q1
FM M T 491A
FAULT
TP2
TP10
C4
470pF
C5
470pF
TP3
R
PC_MON
JU3
R4
50k
Ω
R5
100
Ω
R
BC_MON
JU4
R7
50k
Ω
R6
100
Ω
R34
OPEN
L2
1.0
µ
H
VCC
GND
JU15
C17
0.1
µ
F
J13
J14
C18
10
µ
F
C19
0.1
µ
F
L5
1.0
µ
H
C36
10
µ
F
C39
0.1
µ
F
C41
0.1
µ
F
J8
VCC_OUT
R49
OPEN
JU19
VCC1
2VCC
VCC1
TP14TP16
TP12
TP17
18
17
16
4
5
6
1
2
3
R2
100
Ω
R3
100
Ω
TP15
R25
OPEN
R28
OPEN
VCC1
R41
OPEN R42
OPEN
VCC1
VCC1
R8
4.7k
Ω
C8
20pF
JU8
MAX3738 Evaluation Kit
8 ________________________________________________________________________________________
Evaluates: MAX373
8
Figure 3. MAX3738 EV Kit Schematic—Optical Configuration
C38
0.1
µ
F
C37
0.1
µ
F
IN+
IN-
J4
J5
C33
0.01
µ
F
C23
0.01
µ
F
R35
OPEN
L3
1.0
µ
H
VCC
GND
JU16
TP11
C22
0.1
µ
F
VCC2
R
MO D S E T
R
APCSET
J3
J6
C21
10
µ
F
C20
0.1
µ
F
VCC2
R60
4.7k
Ω
FAULT
R59
511
Ω
Q6
FMMT491
A
D4
LED
TP25
SHUT DOWN
R64
100
Ω
R
PC_MON
R63
100
Ω
R
BC_MON
C35
470pF
C34
470pF
TP27 TP26
VCC2
JU30
R68
100
Ω
TP20
TP19
R37
OPEN
R53
OPEN
R36
OPEN
R57
50k
Ω
R40
OPEN R55
20k
Ω
R45
OPEN
C30
0.01
µ
F
R39
49.9
Ω
VCC2
R56
15
Ω
C24
8.2pF
R54
10
Ω
C25
0.01
µ
F
C26
0.01
µ
F
D3
654
L4
MURAT A
BLM18HG601SN1
SB6
SB5
SB4
SB1 SB2 SB3
LA S E R
PHOTODIODE
1
2
3
(SEE FIGURE 1)
(SEE FIGURE 1)
C28
0.01
µ
F
C29
0.01
µ
F
VCC2
Q4
FDN306P
JU20
R52
OPEN
R38
OPEN
R51
OPEN
VCC2
C40
0.01
µ
F
SHUTDOWN
C31
0.01
µ
F
C27
470pF
R62
3.32k
Ω
R65
332
Ω
VCC2
V
CC
IN+
IN-
V
CC
PC_MON
BC_MON
TX_DISABLE
APCSET
21 20
22 19
U1
MAX3738
APCFILT
2
APCFILT1
MD
V
CC
OUT +
V
CC
BIAS
SHUT DOWN
TX_FAUL
T
GND
10 11
MODSET
OUT -
GND
789
MODBCOMP
TH_TEMP
MODTCOMP
2324
12
TP1
TP5 TP13
TP8
R48
49. 9
Ω
VCC2
R43
OPEN
R44
OPEN
VCC2
R46
OPEN
R47
OPEN
MAX3738 Evaluation Kit
________________________________________________________ 9
Evaluates: MAX3738
Figure 4. MAX3738 EV Kit PC Component Placement
Guide-Component Side
Figure 5: MAX3738 EV Kit PC Component Placement
Guide-Solder Side
MAX3738 Evaluation Kit
10 ________________________________________________________________________________________
Evaluates: MAX373
8
Figure 6. MAX3738 EV Kit PC Board Layout -
Component Side
Figure 7: MAX3738 EV Kit PC Board Layout – Ground
Plane
MAX3738 Evaluation Kit
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________ 11
Evaluates: MAX3738
Figure 8: MAX3738 EV Kit PC Board Layout – Power
Plane
Figure 9: MAX3738 EV Kit PC Board Layout – Solder
Side
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right o change the circuitry and specifications without notice at any time.
2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products
