__________________________________________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: MAX3735A
MAX3735A Evaluation Kit
_______________
______________________________
_______________ General Description
The MAX3735A evaluation kit (EV kit) is an assembled
demonstration board that provides complete optical and
electrical evaluation of the MAX3735A.
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
MAX3735AEVKIT -40°C to +85°C 24 QFN*
*Exposed pad.
________________________________________Electrical Evaluation Component List
DESIGNATION QTY DESCRIPTION
C1, C10, C11,
C13, C14 50.01µF ±10% ceramic
capacitors (0402)
C2, C12, C19,
C20 — Open
C3 1 0.5pF ±10% ceramic
capacitor (0201)
C4, C5, C16,
C17, C18 50.1µF ±10% ceramic
capacitors (0402)
C7, C8, C9 3 470pF ±10% ceramic
capacitors (0402)
C15 1 0.01µF ±10% ceramic
capacitor (0201)
C21 1 10µF ±10% tantalum
capacitor, case B
D1 1 Diode, DIO-S1A
D2 1 LED, red T1 package
J1 1 SMP connector
J2, J3 2 SMA connectors, tab
contact
JU1, JU5, JU6,
JU7, JU9, JU10,
JU13, JU14
8 2-pin headers, 0.1in centers
JU8, JU15 — Open
JU11 — Open
JU25 — Open, 0201 solder bridge
L1, L5 — Open
DESIGNATION QTY DESCRIPTION
Q1 1 MOSFET (SOT23)
Fairchild FDN306P
Q2 — Open
Q3 1 NPN transistor (SOT23)
Zetex FMMT491A
Q4 1 PNP transistor (SOT23)
Zetex FMMT591A
R1, R34–R40 — Open
R2 1 5.1Ω ±1% resistor (0402)
R3, R4, R5 3 30Ω ±1% resistors (0402)
R6 1 75Ω ±1% resistor (0402)
R7 1 200Ω ±1% resistor (0402)
R8 1 392Ω ±1% resistor (0402)
R9 1 511Ω ±1% resistor (0402)
R10 1 1.5kΩ ±1% resistor (0402)
R11 1 4.3kΩ ±1% resistor (0402)
R13 1 0Ω resistor (0603)
R14–R17 4 50kΩ variable resistors
R41 1 0Ω resistor (0201)
U1 1 MAX3735AETG (24 QFN)
U2 1 MAX495ESA (8 SO)
VCC, GND, TP1–
TP11, TP22 14 Test points
None 8 Shunts
None 1 MAX3735 EV board
None 1 MAX3735A data sheet
19-2567; Rev 1, 09/0
3
MAX3735A Evaluation Kit
2 _________________________________________________________________________________________
Evaluates: MAX3735A
_________________________________________Optical Evaluation Component List
DESIGNATION QTY DESCRIPTION
C22, C23, C38,
C39 40.1µF ±10% ceramic
capacitors (0402)
C24 1 8.2pF ±10% ceramic
capacitor (0402)*
C25, C26, C27 3 470pF ±10% ceramic
capacitors (0402)
C28–C35 8 0.01µF ±10% ceramic
capacitors (0402)
C36, C37 2 0.01µF ±10% ceramic
capacitors (0603)
C40 — Open
C41 1 10µF ±10% tantalum
capacitor, case B
D3 — Open, user-supplied laser
diode
D4, D5, D6 3 LED, red T1 Package
J4, J5 2 SMA connectors, tab contact
J6 — Open**
JU16–JU20 5 2-pin headers, 0.1in centers
JU21, JU22 2 3-pin headers, 0.1in centers
L3 1 600Ω ferrite bead (0603)
Murata BLM18HG601SN1
L4 1 1µH inductor (1008CS)
Coilcraft 1008CS-102XKBC
*These components are part of the compensation network, which can reduce overshoot and ringing. Parasitic series
inductance introduces a zero into the laser’s frequency response. R21 and C24 add a pole to cancel this zero. Starting
values for most coaxial lasers is R21 = 49.9Ω in series with C24 = 8.2pF. These values should be experimentally
adjusted until the output waveform is optimized.
**These components are not supplied on the EV kit but can be populated if the customer wants to use the MAX3735A
laser driver with the DS1858 dual temperature controlled digital resistor with current monitors. See schematics on page
8 for details.
______________ Component Suppliers
Note: Please indicate that you are using the MAX3735A when
contacting these component suppliers.
DESIGNATION QTY DESCRIPTION
Q5 1 MOSFET (SOT23)
Fairchild FDN306P
Q6 1 NPN transistor (SOT23)
Zetex FMMT491A
R18 — Open (0402)
R19 1 11Ω ±1% resistor (0402)
R20 1 15Ω ±1% resistor (0402)
R21 1 49.9Ω ±1% resistor
(0402)*
R22 1 200Ω ±1% resistor (0402)
R23 1 511Ω ±1% resistor (0402)
R24 1 1.5kΩ ±1% resistor (0402)
R25 1 4.3kΩ ±1% resistor (0402)
R26, R27 2 4.7kΩ ±1% resistors
(0402)
R28, R29 2 330Ω ±1% resistors
(0603)
R30–R33 4 50kΩ variable resistors
U3 — Open**
U4 1 MAX3735AETG (24 QFN)
VCC, GND,
TP12–TP21 12 Test points
None 7 Shunts
None 1 MAX3735 EV board
None 1 MAX3735A 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
MAX3735A Evaluation Kit
________________________________________________________ 3
Evaluates: MAX3735A
__________________________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 Q4, which is controlled by an
operational amplifier (U2). The APC test circuit consisting
of U2 and Q4 applies the simulated monitor diode current
(the laser bias current divided by a factor of 77) to the MD
pin of the MAX3735A. To ensure proper operation in the
electrical configuration, set up the evaluation board as
follows:
1) Place shunts on JU5, JU6, JU7, JU10 and JU14
(Refer to table 1 for details).
2) If the EV kit is to be used without the optional
shutdown transistor (Q1), place a shunt on JU13.
3) Remove the shunt from JU1 to use the filter inductor.
4) To enable the outputs, connect TX_DISABLE to GND
by placing a shunt on JU9.
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 R15, the RMODSET potentiometer, for 25kΩ
resistance between TP6 and ground.
6) Adjust R16, the RAPCSET potentiometer, for 25kΩ
resistance between TP4 and ground.
7) Adjust R17, the RPC_MON potentiometer, to set the
maximum monitor diode current (IMDMAX, see below).
RPC_MON can be measured from TP10 to ground.
MDMAX
PC_MON I
1.38V
R=
8) Adjust R14, the RBC_MON potentiometer, to set the
maximum bias current (IBIASMAX, see below). RBC_MON
can be measured from TP11 to ground.
BIASMAX
BC_MON I
1.38V76
R×
=
9) Apply a differential input signal (200mVP-P to
2400mVP-P) between SMA connectors J2 and J3 (IN+
and IN-).
10) Attach a high-speed oscilloscope with a 50Ω input to
the SMP connector J1 (OUT+).
Note: J1 has a DC voltage of approximately VCC/2
and can have voltage swings greater than 1V. Care
should be taken that the large swing and DC voltage
do not damage the test equipment. An attenuator
might be needed to make the signal compatible with
the oscilloscope’s input requirements.
11) Connect a +3.3V supply between TP2 (VCC) and TP1
(GND) Adjust the power supply until the voltage
between TP7 and ground is +3.3V.
12) Adjust R16 (RAPCSET) until the desired laser bias
current is achieved.
5.11Ω
V-V
ITP5TP3
BIAS =
13) The MD and BIAS currents can be monitored at
TP10 (VPC_MON) and TP11 (VBC_MON) using the
equation below:
PC_MON
PC_MON
MD R
V
I=
BC_MON
BC_MON
BIAS R
V76
I×
=
Note: If the voltage at TP10 or TP 11 exceeds 1.38V,
the TX_FAULT signal will be asserted and latched.
14) Adjust R15 until the desired laser modulation current
is achieved.
15Ω
(V) Amplitude Signal
IMOD =
Optical Evaluation
For optical evaluation of the MAX3735A, configure the
evaluation kit as follows:
1) Place a shunt on JU18 to connect the FAULT
indicator and remove shunt JU20 to use the filter
inductor.
2) Place a shunt across pin 2 (MODSET) and pin 1
(RMODSET) of JU21. This connects the MODSET pin to
the RMODSET potentiometer (R31).
3) Place a shunt across pin 2 (APCSET) and pin 3
(RAPCSET) of JU22. This connects the APCSET pin to
the RAPCSET potentiometer (R30).
4) If the EV kit is to be used without the optional
shutdown transistor (Q5), place a shunt on JU17.
MAX3735A Evaluation Kit
4 _________________________________________________________________________________________
Evaluates: MAX3735A
5) To enable the outputs, connect TX_DISABLE to GND
by placing a shunt on JU16.
6) 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:
• 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 (Q5)).
• 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.
7) Adjust R31, the RMODSET potentiometer, for maximum
resistance (≈50kΩ) between TP17 and ground. This
sets the modulation current to a low value (<10mA).
(Refer to the Design Procedure section of the
MAX3735A data sheet.)
8) Adjust R30, the RAPCSET potentiometer, for maximum
resistance (≈50kΩ) between TP19 and ground. This
sets the photodiode current to a low value (<18uA).
(Refer to the Design Procedure section of the
MAX3735A 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.
9) Adjust R33, the RPC_MON potentiometer, to set the
maximum monitor diode current (IMDMAX, see below).
MDMAX
PC_MON I
1.38V
R=
10) Adjust R32, the RBC_MON potentiometer, to set the
maximum bias current (IBIASMAX, see below).
BIASMAX
BC_MON I
1.38V76
R×
=
11) Apply a differential input signal (200mVP-P to
2400mVP-P) between SMA connectors J5 and J4 (IN+
and IN-).
12) Attach the laser diode fiber connector to an
optical/electrical converter.
13) Connect a +3.3V supply between TP12 (VCC) and
TP13 (GND). Adjust the power supply until the
voltage between TP15 and ground is +3.3V.
14) Adjust R30 (RAPCSET) until the desired average optical
power is achieved.
15) The MD and BIAS currents can be monitored at
TP16 (VPC_MON) and TP18 (VBC_MON) using the
equations below:
PC_MON
PC_MON
MD R
V
I=
BC_MON
BC_MON
BIAS R
V76
I×
=
Note: If the voltage at TP16 or TP18 exceeds 1.38V,
the TX_FAULT signal will be asserted and latched.
16) Adjust R31 (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
R21 and C24, as described in the Design Procedure
section of the MAX3735A data sheet.
MAX3735A Evaluation Kit
________________________________________________________ 5
Evaluates: MAX3735A
______________ Adjustment and Control Descriptions (see Quick Start first)
COMPONENT
OPTICAL ELECTRICAL NAME FUNCTION
D6 D2 Fault
Indicator
LED is illuminated when a fault condition has occurred
(Refer to the Detailed Description section of the
MAX3735A data sheet).
JU22 — —
Connects the APCSET pin to either the potentiometer
or the Dallas digital resistor. Shunt pin 2 to pin 3 when
using the potentiometer. Shunt pin 2 to pin 1 when
using the Dallas DS1858 controller IC.
JU21 — —
Connects the MODSET pin to either the potentiometer
or the Dallas digital resistor. Place a shunt on pin 2 to
pin 1 when using the potentiometer. Place a shunt on
pin 2 to pin 3 when using the Dallas DS1858 controller
IC.
JU19 — WP Can be used to enable and disable the write protection
feature of the DS1858 controller IC.
JU20 JU1 —
Placing a shunt on JU1 or JU20 removes the inductor
from the filter networks by shorting the inductor lead
together. Remove shunts for normal operation.
JU18 JU5 —
Place a shunt on JU18 or JU5 to connect the open
collector FAULT output to the LED indicator. The LED is
illuminated when FAULT is asserted.
—JU6—
Placing a shunt on JU6 connects the MODSET pin of
the MAX3735A to the RMODSET potentiometer.
—JU7—
Placing a shunt on JU7 connects the emulated monitor
diode current to the MD pin of the MAX3735A.
JU16 JU9 TX_DISABLE Enables/disables the output currents. Active low (shunt
across JU9 or JU16 to enable output currents).
—JU10—
Placing a shunt on JU10 connects the APCSET pin of
the MAX3735A to the RAPCSET potentiometer.
JU17 JU13 — Installing a jumper on JU13 or JU17 disables the
optional shutdown transistors.
R31 R15 RMODSET Adjusts the laser modulation current
R30 R16 RAPCSET Adjusts the monitor diode current level to be maintained
by the APC loop
TP14 TP8 Fault
TTL high level indicates a fault condition. Installing and
then removing JU16 for the optical section or JU9 for
the electrical section will clear the fault condition (Refer
to the Detailed Description section of the MAX3735A
data sheet).
MAX3735A Evaluation Kit
6 _________________________________________________________________________________________
Evaluates: MAX3735A
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 MAX3735A EV Kit
MAX3735A Evaluation Kit
_______________________________________________________ 7
Evaluates: MAX3735A
C4
0.1µF
C5
0.1µF
IN+
IN-
J2
J3
VCC
IN+
IN-
VCC
PC_MON
BC_MON
TX_DISABLE
APCSET
C10
0.01µF
TP4
1
2
3
4
5
6
C11
0.01µF
C9
470pF
24 23 22 21 20 19 VCC1
C12
OPEN
U4
MAX3735A
APCFILT2
APCFILT1
MD
VCC
OUT-
OUT+
OUT+
VCC
BIAS
18
17
16
15
14
13
R10
1.5kΩ
TP6
VCC1
JU5
GND
V
CC
SHUTDOWN
FAULT
MODSET
GND
7 8 9101112
R1
OPEN
L2
1µH
VCC
GND
JU1
TP7
C16
0.1µF
C20
OPEN
VCC1
R3
30Ω
R6
75Ω
VCC1
RMODSET
GND
JU9
R7
200Ω
R16
50kΩ
RAPCSET
TP2
TP1
C21
10µF
C18
0.1µF
VCC1
R11
4.3kΩ
FAULT
R9
511Ω
Q3
FMMT491A
D2
LED TP8
R15
50kΩ
VCC1
Q1
FDN306P
SHUTDOWN2
SHUTDOWN2
C13
0.01µF
R17
50kΩ
RPC_MON
R14
50kΩRBC_MON
C7
470pF
C8
470pF
TP10
TP11
JU13
7
6
4
2
3
VCC1
C14
0.01µF
U2
Q4
FMMT591A
MD
R2
5.1Ω
BIAS
R8
392Ω
C17
0.1µF
D1
DIO-S1A
JU11
TP3
MAX495
BIAS
R4
30ΩVCC1
R5
30Ω
C3
0.5pF
JU7
C15
0.01µF
JU6
MD
JU10
VCC1
JU14
JU15
OPEN
TP9
L1
OPEN
R13
0Ω
C19
OPEN
JU8
OPEN
J1
OUT+
JU25
R38
OPEN
VCC1
R39
OPEN
R40
OPEN
L5
OPEN
C2
OPEN
R35
OPEN
R36
OPEN
R37
OPEN
R34
OPEN
TP22
TP5
C1
0.01µF
R41
0Ω
Q2
OPEN
Figure 2. MAX3735A EV Kit Schematic—Electrical Configuration
MAX3735A Evaluation Kit
8 ________________________________________________________________________________________
Evaluates: MAX3735A
C23
0.1µF
C22
0.1µF
IN+
IN-
J5
J4
V
CC
IN+
IN-
V
CC
PC_MON
BC_MON
TX_DISABLE
APCSET
C30
0.01µF
TP19
1
2
3
4
5
6
C31
0.01µF
C27
500pF
24 23 22 21 20 19 VCC2
C33
0.01µF
U4
MAX3735A
APCFILT2
APCFILT1
MD
R21
49.9Ω
V
CC
OUT-
OUT+
OUT+
V
CC
BIAS
18
17
16
15
14
13
JU21
R24
1.5kΩ
TP17
VCC2
JU18
GND
V
CC
SHUTDOWN
FAULT
MODSET
GND
789101112
R18
OPEN
VCC2
L4
1µH
VCC
GND
JU20
TP15
C38
0.1µF
C40
OPEN
VCC2
R20
15Ω
C24
8.2pF
R19
11ΩC32
0.01µF
C36
0.01µF
D3
654
L3
MURATA
BLM18HG601SN1
VCC2
SB6
SB5
SB4
SB1 SB2 SB3
LASER
PHOTODIODE
1
2
3
(SEE FIGURE 1)
(SEE FIGURE 1)
H1
R
MODSET
GND
JU16
R22
200Ω
JU22
1
R30
50kΩ
R
APCSET
C34
0.01µF
TP12
TP13
C41
10µF
C39
0.1µF
VCC2
R25
4.3kΩ
FAULT
R23
511Ω
Q6
FMMT491A
D6
LED TP14
1
H0
R31
50kΩ
C37
0.01µF
C35
0.01µF
VCC2
Q5
FDN306P
SHUTDOWN2
SHUTDOWN2
1
2
3
4
5
6
D4
LED
D5
LED
R28
330Ω
R29
330Ω
TP21
PHONE
JACK
TP20
VCC2
C28
0.01µF
R26
4.7kΩ
R27
4.7kΩ
VCC2
A2
A1
A3
A4
B1 B2 B3 B4
C1
C2
C3
C4
D4 D3 D2 D1
IN1
SCL
V
CC
H0
OUT2
SDA
H1
L0
WP
IN2
OUT1
MON3
GND
L1
MON1
MON2
C29
0.01µF
DS1858
BGA
U3
R33
50kΩ
R
PC_MON
R32
50kΩ
R
BC_MON
H1
H0
JU19
C26
470pF
C25
470pF
TP16
TP18
VCC2
JU17
J6
VCC2
WP
SDA
SCL
Figure 3. MAX3735A EV Kit Schematic—Optical Configuration
MAX3735A Evaluation Kit
_______________________________________________________ 9
Evaluates: MAX3735A
Figure 4. MAX3735A EV Kit PC Component Placement
Guide—Component Side
Figure 5. MAX3735A EV Kit PC Component Placement
Guide—Solder Side
MAX3735A Evaluation Kit
10 ________________________________________________________________________________________
Evaluates: MAX3735A
Figure 6. MAX3735A EV Kit PC Board Layout—
Component Side
Figure 7. MAX3735A EV Kit PC Board Layout—Ground
Plane
MAX3735A Evaluation Kit
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 to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600___________________11
2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products
Evaluates: MAX3735A
Figure 8. MAX3735A EV Kit PC Board Layout—Power
Plane
Figure 9. MAX3735A EV Kit PC Board Layout—Solder
Side
