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19-1110; Rev 0; 8/96
MAX3962 Evaluation Kit
_______________General Description
The MAX3962 evaluation kit (EV kit) simplifies evalua-
tion of the MAX3962 LAN LED driver. The load for the
MAX3962 can be a user-supplied, light-emitting diode
(LED) or a resistive load that emulates an LED. The
MAX3962 EV kit provides controls for easy adjustment
of modulation and peaking currents. It also provides
controls for adjusting the modulation-current tempera-
ture coefficient and output pulse width. Signal inputs
can be single-ended or differential, and can be AC or
DC coupled as needed.
The MAX664 is used to implement a PECL termination
for the input signal.
____________________________Features
o
Tests MAX3962 with Inductive Electrical Load
or LED
o
PECL Termination Provided
o
Easy Adjustment of Modulation and Peaking
Currents
o
Single-Ended or Differential Input
o
Adjustment of Modulation-Current Temperature
Coefficient
o
Output Pulse-Width Adjustment
o
Fully Assembled and Tested
Evaluates: MAX3962
______________Component Suppliers
SUPPLIER
AVX
Central
Semiconductor
Zetex USA
PHONE
(803) 946-0690
(516) 435-1110
(516) 543-7100
FAX
(803) 626-3123
(516) 435-1824
(516) 864-7630
______________Ordering Information
PART
MAX3962EVKIT-SO
TEMP. RANGE
0°C to +70°C
BOARD TYPE
Surface Mount
_____________________________________________________________Component List
DESIGNATION QTY
C1, C4
C2
C3
C5, C8
C6, C7, C11,
C13, C15,
C17, C18
C10
C12, C14
D1
D2
J2, J3, J5, J6
JP4–JP10
Q1
2
1
1
2
7
1
2
1
1
4
7
1
DESCRIPTION
10µF, ±10%, 16V tantalum capacitors
AVX TAJB106K
1µF, ±10%, 16V tantalum capacitor
AVX TAJB105K
0.022µF, 25V ceramic capacitor
0.1µF, 25V ceramic capacitors
1000pF, 25V ceramic capacitors
100pF, 25V ceramic capacitor
0.22µF, 16V ceramic capacitors
User-supplied, light-emitting diode
Switching diode
Central Semiconductor CMPD7000BK
SMA connectors, edge mount
2-pin headers
PNP transistor
Zetex FMMT591A
DESIGNATION QTY
R1
R2, R3
R4, R5
R6, R10, R17,
R18, R19
R7, R8
R11, R12
R13
R14
R15
R16
R20
TP2, TP6,
TP7, TP8
U1
U2
None
1
2
2
5
2
2
1
1
1
1
1
4
1
1
4
0Ω resistor
15Ω, 1% resistors
10kΩ, 1% resistors
100kΩ potentiometers
453Ω, 1% resistors
49.9Ω, 1% resistors
221Ω, 1% resistor
1.5kΩ, 1% resistor
4.75kΩ, 1% resistor
2kΩ, 1% resistor
121Ω, 1% resistor
Test points
MAX3962CEI
MAX664CSA
Shunts
DESCRIPTION
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
MAX3962 Evaluation Kit
Evaluates: MAX3962
_________________________Quick Start
The MAX3962 EV kit is fully assembled and tested.
Follow the steps below to verify board operation:
1) Verify that shunts are installed on JP8 and JP10.
Verify that shunts are removed from JP4, JP5, JP6,
JP7, and JP9. Verify solder shorts across SB26 and
SB19.
2) Turn R17, R18, and R19 fully counter-clockwise.
3) Connect differential signal inputs to VIN+ and VIN-.
The signal should resemble a square wave, with a
data rate between 100Mbps and 300Mbps. Signal
amplitude should be 0.5V to 1.0V per input. The EV
kit inputs are AC terminated to 50Ω.
4) Connect outputs IOUT+ and IOUT- with matched
cables to an oscilloscope with 50Ω inputs.
5) Connect a +3.3V power supply to the user pad
labeled VCC, adjacent to C1. Set the current limit
above 200mA.
6) Connect the power-supply ground to the user pad
marked GND.
7) Adjust the oscilloscope vertical gain of both chan-
nels to
≈10mV/div.
Set the oscilloscope to display
the differential signal (IOUT+ - IOUT-).
8) Adjust MOD (R17) until a waveform is observed.
Jumper JP9 (TP)
Install a shunt on JP9 for DC testing of overshoot and
undershoot current. Overshoot current flows into the
cathode if the input is high. Undershoot current is
sourced from the cathode if the input is low. Do not
install a shunt on JP4 (disable) if JP9 is shunted.
Table 1. Modulation-Current TC
Programming Mode
MODE
Minimum TC: 2100ppm/°C
Variable TC: 2100ppm/°C–
13,000ppm/°C (using R10)
Nominal TC: 7300ppm/°C
Maximum TC: 14,500ppm/°C
JP6
Short
Open
Open
Open
JP7
Open
Short
Open
Open
JP8
Open
Open
Short
Open
Jumper JP10 (Input Termination Voltage)
The input termination voltage (V
TT
) is selectable with
jumper JP10. Short JP10 to set V
TT
= V
CC
- 1.3V when
using AC-coupled inputs. Remove JP10 to set V
TT
=
V
CC
- 2.0V when using DC-coupled inputs. The inputs
can be DC coupled by shorting C12 and C14.
SB19 (Internal Compensation)
Short SB19 with solder to connect the internal compen-
sation network to the LED cathode. Refer to the
MAX3962 data sheet for more information about the
compensation network. External compensation can be
added at R9 and C16, if desired.
SB26 (LV, Low-Voltage Configuration)
For maximum modulation current when using a 5V sup-
ply, remove solder from SB26 to disconnect the LV pin.
For more information, refer to the
Output Drivers
section
in the MAX3962 data sheet.
SB19 and SB26 are low-inductance jumpers imple-
mented as gaps in the traces connecting pins 19 and
26 (respectively). These jumpers can be shorted and
opened with a soldering iron.
Output Pulse-Width Adjustment
R6 adjusts the output pulse width if JP5 is installed.
Variable TC Adjustment
R10 adjusts the modulation-current TC if properly
enabled (Table 1).
Modulation-Current Adjustment
R17 adjusts the modulation current.
_______________Detailed Description
Adjustments and Controls
Jumper JP1
Cut JP1 to measure power-supply current or to inject
noise on the supply via J1 (J1 is not installed).
Jumpers JP2 (VIN+) and JP3 (VIN-)
Cut JP2 and JP3 to measure VIN+ and VIN- input bias
current. Cut JP3 if connecting V
BB
to VIN- for single-
ended operation.
Jumper JP4 (Disable)
Install JP4 to disable the data input. The MAX3962 out-
put is forced low when JP4 is installed.
Jumper JP5 (Pulse-Width-Adjust Enable)
Install a shunt on JP5 if output pulse-width adjustment
is desired.
Jumpers JP6, JP7, and JP8 (TC Programming)
The MAX3962 has a programmable modulation-current
temperature coefficient (TC). Use Table 1 to select the
desired TC. Refer to the MAX3962 data sheet for more
information.
2
_______________________________________________________________________________________
MAX3962 Evaluation Kit
Overshoot-Current Adjustment
R18 adjusts the overshoot current.
Undershoot-Current Adjustment
R19 adjusts the undershoot current.
DC Measurements
To measure DC output current, install an ammeter
across D1. To measure undershoot and overshoot cur-
rents, install a shunt on JP9.
Evaluates: MAX3962
Output Measurements
Resistive Load
When using an oscilloscope with 50Ω inputs, the output
current is (V
IOUT+
- V
IOUT-
)1.333.
LED Load
Before installing a user-supplied LED, modify the EV kit
as follows:
1) Remove C5, C13, R2, R3, and D2.
2) The EV kit provides convenient sockets for in-
stalling an LED (D1). Connect the LED anode to the
MAX3962’s anode pin. Connect the LED cathode to
the MAX3962’s cathode pin. Two ground sockets
are provided adjacent to D1.
3) Trim the LED leads to reduce inductance.
4) Turn R17, R18, and R19 fully counter-clockwise.
5) Apply power and adjust R17 to obtain an output
waveform.
6) Adjust R18 and R19 to optimize the optical wave-
form.
Input Connections
The MAX3962 EV kit inputs can be driven with either a
single-ended signal generator or a differential signal
generator.
When using a single-ended generator with a DC-cou-
pled input (C12 shorted), cut JP3 and connect VIN- to
V
BB
.
Layout Considerations
The MAX3962 uses a four-layer board with separate
power and ground planes. The signal inputs use 50Ω
transmission lines. The VCCOUT pin is bypassed close
to the package to reduce noise on the power supply.
The VEEOUT pin connects to the ground plane with a
short trace and multiple vias. The electrical path from
anode to cathode, through the LED, is kept as short as
possible to reduce inductance.
_______________________________________________________________________________________
3
Evaluates: MAX3962
VCC
–
B
VCC
–
A
J1 (NOT INSTALLED)
VCC
C3
0.022µF
VCC_B
TP1
PWC
3
C6
1000pF
JP4
TP5
SB26
VCC
–
B
2
D1
LED
C10
100pF
C11
1000pF
C7
1000pF
TP4
R6
1 100k
R4
10k
VCC_B
R5
10k
I
OUT+
R7
J3
MAX3962 Evaluation Kit
Figure 1. MAX3962 EV Kit Schematic
JP1
CUT HERE
C1
10µF
16V
C2
1µF
16V
4
U1
2
JP5
JP2
CUT HERE
TP2
JP3
CUT HERE
VCC_B
R1
0Ω
L1
VCC
OPEN
GND
MAX3962
JP9
C5
453
0.1µF
R2
15Ω
C8
0.1µF
R8
453Ω
J2
I
OUT-
C12
J5 0.22µF
V
IN+
1
R3
15Ω
D2
1
C13
1000pF
3
J6
C14
0.22µF
V
IN-
R12 TP3
49.9Ω
TP11
TC MIN
JP6
R10
3 VAR TC JP7
VCC_B
TP7
TP8
C15
1000pF
R14
1.5k
R16
2k
3
2
1
3
2
3
R15
4.75k
JP8
2
TCNOM
C16
OPEN
SB19
R9
OPEN
1
100k
C18
1000pF
R11
49.9Ω
1
2
3
4
5
6
7
8
9
10
11
12
13
14
TP6
DISABLE
V
CC
PWCREF
PWC
V
EE
IN+
IN-
V
BB
V
EE
TCMIN
TCNOM
TC
V
CC
MOD
N.C.
TP
LV
VCCOUT
VCCOUT
ANODE
ANODE
CATHODE
CATHODE
COMP
VEEOUT
VEEOUT
US
OS
28
27
26
25
24
23
22
21
20
19
18
17
16
15
C17
1000pF
U2
VCC
–
A
VCC
–
A
C4
10µF
16V
5
SHDN2
3
SHDN1
VIN
R13
VCC
–
A
221Ω
GND
8
VCC
–
A
R20
121Ω
4
MAX664
R17
100k
MOD
R18
100k
OS
1
R19
2 100k
US
1
VTT
7
2 VOUT1
SENSE
1
VOUT2
VSET
6
Q1
1
_______________________________________________________________________________________
3
JP10
INSTALL WHEN INPUTS ARE AC COUPLED
MAX3962 Evaluation Kit
Evaluates: MAX3962
Figure 2. MAX3962 EV Kit Component Placement Guide—Component Side
Figure 3. MAX3962 EV Kit PC Board Layout
_______________________________________________________________________________________
5

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