General Description
The MAX3669ETG evaluation kit (EV kit) is an assembled
demonstration board that provides easy optical or elec-
trical evaluation of the MAX3669ETG, a 622Mbps laser
driver with current monitors and automatic power control
(APC) circuitry. Although the MAX3669ETG EV kit is
shipped in the electrical configuration, this EV kit also
provides configuration instructions for optical operation.
Features
♦Fully Assembled and Tested
♦+3.3V or +5V Operation
♦On-Board Input Termination
♦Independent Electrical Monitoring of Modulation
and Bias Currents
Evaluates: MAX3669ETG
MAX3669ETG Evaluation Kit
________________________________________________________________ Maxim Integrated Products 1
19-2602 Rev 0; 10/02
Component List for Electrical Configuration
Ordering Information
Component Suppliers
Note: Please indicate that you are using the MAX3669ETG
when contacting these component suppliers.
PART TEMP RANGE IC PACKAGE
MAX3669ETGEVKIT -40°C to +85°C 24 QFN
SUPPLIER PHONE FAX
AVX 843-448-9411 843-448-1943
Coilcraft 847-639-6400 847-639-1469
Murata 770-436-1300 770-436-3030
Zetex 631-360-2222 631-360-8222
DESIGNATION QTY DESCRIPTION
C1, C2, C6,
C12, C20 50.01µF ±10% ceramic capacitors
(0402)
C4, C7, C10,
C11 41µF ±10% ceramic capacitors
(0603)
C5 1 Do not install
C8 1 100pF ±10% ceramic capacitor
(0402)
C16 1 0.1µF ±10% ceramic capacitor
(0603)
C19 1
10µF ±10%, 10V min tantalum
capacitor, case B
AVX TAJC106K016
C21 1 5pF ±5% ceramic capacitor (0402)
D1 1 LED
J1, J2, J3 3 SMA connectors, edge mount
L3 1 1.2µH inductor
Coilcraft 1008LS-122XKBC
P1 1 2-pin header, 0.1in centers
None 1 Shunt for P1
Q1 1 PNP transistor
Zetex FMMT591A
R1, R2, R24 3 1.5kΩ ±5% resistors (0402)
R3 1 1kΩ ±5% resistor (0603)
R5 1 12.4Ω ±1% resistor (0402)
DESIGNATION QTY DESCRIPTION
R6, R7, R21 3 84.5Ω ±1% resistors (0603)
R8, R9 2 124Ω ±1% resistors (0603)
R10, R11 2 20Ω ±1% resistors (0402)
R12 1 10Ω ±1% resistor (0402)
R13, R22 2 0Ω resistors (0603)
R14 1 50kΩ variable resistor
Bourns 3296W
R15 1 200kΩ variable resistor
Bourns 3296W
R16 1 100kΩ variable resistor
Bourns 3296W
R18 1 110Ω ±5% resistor (0603)
R20 1 0Ω resistor (0402)
R23 1 15Ω ±5% resistor (0603)
R26, R28 2 392Ω ±1% resistors (0402)
R27, R29 2 Do not install
VCC, GND, TP1,
TP4, TP5, TP6,
TP8–TP11
10 Test points
U1 1 MAX3669ETG (24-pin QFN)
U3 1 MAX495ESA (8-pin SO)
None 1 MAX3669 data sheet
None 1 MAX3669ETG EV kit PC board,
rev A
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: MAX3669ETG
MAX3669ETG Evaluation Kit
2 _______________________________________________________________________________________
Quick Start
Electrical Setup (Default)
In the electrical configuration, an APC test circuit is
included to emulate a semiconductor laser with a moni-
tor photodiode. Monitor diode current is provided by Q1,
which is controlled by an operational amplifier (U3). The
APC test circuit, consisting of U3 and Q1, applies the
simulated monitor diode current to the MAX3669ETG’s
MD pin. The ratio of IBIAS / IMD is R24 / R23 = 100. To
ensure proper operation in the electrical configuration,
set up the evaluation board as follows:
1) Verify inductor L2 is not installed.
2) Remove the shunt from P1 to enable the output.
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.
3) Adjust R14, the MOD (RMODSET) potentiometer, for
10kΩresistance between pins 2 and 3 (test point 5
and ground).
4) Adjust R15, the BIAS (RBIASMAX) potentiometer, for
10kΩresistance between pins 2 and 3 (test point 4
and ground).
5) Adjust R16, the APC (RAPCSET) potentiometer, for
10kΩresistance between pins 2 and 3 (test point 6
and ground).
6) Power up the board with a +3.3V supply.
7) Apply a differential input signal (max amplitude
≤800mV per side) to J1 and J2 (DATA+ and DATA-).
8) Attach a high-speed oscilloscope with 50Ωinputs
to J3.
9) Adjust RBIASMAX (R15) and RAPCSET (R16) until the
desired laser-bias current is achieved (refer to the
note in the Applications Information section of the
MAX3669 data sheet).
10) Adjust RMODSET (R14) until the desired laser-modu-
lation current is achieved.
Note: See the Adjustment and Control Descriptions table.
Optical Setup
For optical operation, the electrical APC test circuit
must be disabled. For optical evaluation of the
MAX3669ETG, configure the EV kit as described in
Component Modifications for Optical Configuration:
1) Remove the shunt from P1 to enable the output.
2) Connect a TO-style header laser and monitor diode
(Figure 1) as follows:
•Keeping the leads to the laser diode as short as
possible, connect the laser diode on the compo-
nent side of the board between R20 and VCC
with the cathode connected to R20 and the
anode connected to VCC.
•Connect the monitor diode on the underside of the
the board with the anode connected to the
MAX3669ETG’s MD pin and the cathode con-
nected to VCC.
Note: When performing resistance checks, manually
set the ohmmeter to a high range to avoid forward bias-
ing the on-chip ESD protection diodes.
3) Adjust R14, the MOD (RMODSET) potentiometer, for
maximum resistance between pins 2 and 3 (test
point 5 and ground).
4) Adjust R15, the BIAS (RBIASMAX) potentiometer, for
maximum resistance between pins 2 and 3 (test
point 4 and ground).
5) Adjust R16, the APC (RAPCSET) potentiometer, for
desired optical power. (Refer to the Design
Procedure section of the MAX3669 data sheet.)
6) Power up the board with a +3.3V supply.
7) Apply a differential input signal (≤800mV per side)
to J1 and J2 (DATA+ and DATA-).
8) Attach the laser-diode output to an optical/electrical
converter.
Component Modifications
for Optical Configuration
DESIGNATION QTY DESCRIPTION
J3 1 Remove
L2 1 Ferrite bead
Murata BLM18HG601SN1
R5 1 Remove
R13 1 Remove
R19 1 20Ω ±5% resistor (0402)
R20 1 5Ω ±5% resistor (0402)
R22 1 Remove
R23 1 Remove
U2 1 User-supplied laser diode
9) Adjust R15 until LED D1 is no longer illuminated.
Laser power can be monitored at the laser diode
with an optical/electrical converter (refer to the note
in the Applications Information section of the
MAX3669 data sheet).
10) Adjust R14 until the desired optical amplitude is
achieved. Optical amplitude can be observed on
an oscilloscope connected to an optical/electrical
converter.
Evaluates: MAX3669ETG
MAX3669ETG Evaluation Kit
_______________________________________________________________________________________ 3
Adjustment and Control Descriptions
See Quick Start first.
COMPONENT NAME FUNCTION
D1 APC Fail Indicator LED
Refer to the Design section of the MAX3669 data sheet. Set APC current; then
increase bias current until LED goes off (LED is illuminated when the APC loop is
open and off when the APC loop is closed).
J3 Electrical Output SMA Electrical output. Remove for optical operation.
P1 OUTPUT DISABLE Enable/disable the output currents. Shunting disables the part. Remove shunt for
normal operation.
R14 RMODSET Laser modulation current adjustment
R15 RBIASMAX Laser-bias current adjustment. In open-loop mode, R15 adjusts the laser-bias
current. In closed-loop operation, R15 adjusts the maximum laser-bias current.
R16 RAPCSET Automatic power-control adjustment. For closed-loop operation, R16 adjusts the
monitor-diode current level.
TP1 Fail Indicator Test Point TTL low level indicates a failure in the APC loop.
Evaluates: MAX3669ETG
MAX3669ETG Evaluation Kit
4 _______________________________________________________________________________________
TOP OF PC BOARD
VCC
VCC
L2 D3
LD
PD
BOTTOM OF PC BOARD
TO-46 CAN
LASER/PHOTODIODE
PAIR
VCC
VCC
SOLDER
BRIDGES
CONFIGURATION 4
Figure 1. Attachment of Laser Diode/Monitor Diode to MAX3669ETG EV Kit
TOP OF PC BOARD
L2 D3
BOTTOM OF PC BOARD
LD TO-46 CAN
LASER/PHOTODIODE
PAIR
VCC
VCC
VCC
VCC
SOLDER
BRIDGES
PD
CONFIGURATION 1
TOP OF PC BOARD
VCC
VCC
L2 D3
TO-46 CAN
LASER/PHOTODIODE
PAIR
BOTTOM OF PC BOARD
VCC
VCC
SOLDER
BRIDGES
LD
PD
CONFIGURATION 2
TOP OF PC BOARD
VCC
VCC
L2 D3
LD
PD
BOTTOM OF PC BOARD
TO-46 CAN
LASER/PHOTODIODE
PAIR
VCC
VCC
SOLDER
BRIDGES
CONFIGURATION 3
Evaluates: MAX3669ETG
MAX3669ETG Evaluation Kit
_______________________________________________________________________________________ 5
R15
200kΩRBIASMAX
CW
MAX3669ETG
BIAS
GND
N.C.
FAIL
GND
ENABLE
VCC
DATA+
DATA-
GND
BIASMON
MD
GND
VCC
OUT-
OUT+
VCC
VCC
MODMON
VCC
CAPC
APCSET
GND
MODSET
BIASMAX
J2 C11
1µF
C10
1µF
J1
R9
124Ω
R7
84.5Ω
VCC
R8
124Ω
R6
84.5Ω
VCC
4
3
2
1
VCC R26
392Ω
R27
OPEN
TP8
VCC R28
392Ω
R29
OPEN
TP11
6
5
U1
C7
1µF
R10
20Ω
R20
0Ω
R19
OPEN
C21
5pF
BIAS
MD
R5
12.4Ω
R11
20ΩC4
1µF
VCC
R12
10Ω
C5
OPEN
TP1
VCC
R18
110Ω
R1
1.5kΩ
TP4
R2
1.5kΩ
TP5
R3
1.0kΩ
TP6
VCC
C2
0.01µF
C1
0.01µF
C16
0.1µF
VCC
C8
100pF
BIAS
MD
64
7
U3 3
2
VCC
C6
0.01µF
R13
0Ω
R24
1.5kΩ
R22
0Ω
R23
15Ω
VCC
VCC
TP9
TP10
Q1
2
3
1
L3
1.2µH
84.5Ω
R21
P4
P5 C19
10µFC12
0.01µFC20
0.01µF
VCC
VCC
GND
D1
RED
16
17
18
13
14
15
10 11 12789
21 20 1924 23 22
L2
OPEN
R14
50kΩRMODSET
CW
R16
100kΩRAPCSET
CW
J3
DATA+
DATA-
OUT
P1
Figure 2. MAX3669ETG EV Kit Schematic—Electrical Configuration
Evaluates: MAX3669ETG
MAX3669ETG Evaluation Kit
6 _______________________________________________________________________________________
R15
200kΩRBIASMAX
CW
MAX3669ETG
BIAS
GND
N.C.
FAIL
GND
ENABLE
VCC
DATA+
DATA-
GND
BIASMON
MD
GND
VCC
OUT-
OUT+
VCC
VCC
MODMON
VCC
CAPC
APCSET
GND
MODSET
BIASMAX
C10
1µF
J1
R9
124Ω
R7
84.5Ω
VCC
R8
124Ω
R6
84.5Ω
VCC
4
3
2
1
VCC R26
392Ω
R27
OPEN
TP8
VCC R28
392Ω
R29
OPEN
TP11
6
5
U1
C7
1µF
R10
20Ω
VCC
R20
5Ω
R19
20Ω
C21
5pF
BIAS
MD
R5
OPEN
R11
20ΩC4
1µF
VCC
R12
10Ω
C5
OPEN
TP1
VCC
R18
110Ω
R1
1.5kΩ
TP4
R2
1.5kΩ
TP5
R3
1.0kΩ
TP6
VCC
C2
0.01µF
C1
0.01µF
C16
0.1µF
VCC
C8
100pF
BIAS
MD
64
7
U3 3
2
VCC
C6
0.01µF
R13
OPEN
R24
1.5kΩ
R22
OPEN
R23
OPEN
VCC
VCC
TP9
TP10
Q1
2
3
1
L3
1.2µH
84.5Ω
R21
P4
P5 C19
10µFC12
0.01µFC20
0.01µF
VCC
VCC
GND
D1
RED
16
17
18
13
14
15
10 11 12789
21 20 1924 23 22
L2
MURATA
BLM18HG601SN1
R14
50kΩRMODSET
CW
R16
100kΩRAPCSET
CW
J2 C11
1µF
DATA+
DATA-
P1
Figure 3. MAX3669ETG EV Kit Schematic—Optical Configuration
Evaluates: MAX3669ETG
MAX3669ETG Evaluation Kit
_______________________________________________________________________________________ 7
Figure 5. MAX3669ETG EV Kit PC Board Layout—Component
Side
Figure 4. MAX3669ETG EV Kit Component Placement Guide—
Component Side
1.0"
1.0"
1.0"
1.0"
Figure 6. MAX3669ETG EV Kit PC Board Layout—Solder Side Figure 7. MAX3669ETG EV Kit PC Board Layout—Ground
Plane
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.
8_____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Evaluates: MAX3669ETG
MAX3669ETG Evaluation Kit
1.0"
Figure 8. MAX3669ETG EV Kit PC Board Layout—Power Plane
