MAXIM MAX3781

19-1763; Rev 1; 10/01
MAX3781 Evaluation Kit
Features
♦ Fully Assembled and Tested
♦ +3.3V Operation
♦ On-Board Output Termination
♦ Easy Selection of Operating Modes
Ordering Information
Component List
DESIGNATION
QTY
PART
TEMP RANGE
IC PACKAGE
MAX3781EVKIT
0°C to +85°C
48 TQFP-EP*
DESCRIPTION
C1−C24,
C27−C30
28
0.1µF ±10%, 25V min ceramic
capacitors (0603)
C25
1
33µF tantalum capacitor (C)
C26
1
2.2µF ±10%, 25V min tantalum
capacitor (B)
R1, R2, R3
3
1kΩ ±1% resistors (0603)
R4−R9
6
100Ω ±1% resistors (0603)
L1
1
4.7nH inductor
TOKOLL1608-FH4N7K
SUPPLIER
AVX
PHONE
803-946-0690
FAX
803-626-3123
U1
1
MAX3781UCM 48-pin TQFP-EP
TOKO
800-745-8656
847-699-7864
J1–J24
24
SMA connectors (PC mount)
EFJohnson 142-0701-301
JU1, JU2, JU3
3
2-pin headers (0.1in centers)
Digi-Key S1012-36-ND
JU1, JU2, JU3
3
Shunts
Digi-Key S9000-ND
VCC, GND
2
Test points
Digi-Key 5000-ND
1) Apply +3.3V to the VCC pin. Connect power-supply
ground to the GND pin.
None
1
MAX3781 EV kit circuit board, rev A
None
1
MAX3781 data sheet
2) Shunt jumpers JU1 (SELA), JU2 (PD), and JU3
(SELB). Refer to Table 1 in the MAX3781 data sheet
for other configurations.
*Exposed pad
Component Suppliers
Note: Please indicate that you are using the MAX3781 when
contacting these component suppliers.
Quick Start
3) Apply up to 2.75Gbps differential data to LI2A±
(J17 and J18).
4) Remove R9 (differential termination resistor) from
the evaluation board.
5) Connect SOA± (J23 and J24) to a high-speed 50Ω
oscilloscope.
________________________________________________________________ Maxim Integrated Products
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.
1
Evaluates: MAX3781
General Description
The MAX3781 evaluation kit (EV kit) is an assembled
demonstration board that provides easy evaluation of
the MAX3781 multiplexer/buffer. The MAX3781 EV kit
provides 100Ω differential output terminations onboard, simplifying termination of unused outputs.
Evaluates: MAX3781
MAX3781 Evaluation Kit
Detailed Description
Connecting CML Outputs to 50Ω
Oscilloscopes
CML outputs have a common-mode voltage near VCC.
To avoid changing this optimum common-mode voltage, all CML outputs are AC-coupled on-board with
0.1µF capacitors. The CML outputs should not be connected directly through 50Ω to ground.
Terminating Unused Outputs
The MAX3781 EV kit has 100Ω differential resistors
placed across all outputs. These resistors must be
removed before connecting the outputs to a 50Ω oscilloscope. For best performance, keep all outputs terminated, either to a 50Ω measurement device or to the
100Ω differential resistor.
2
Control Lines
Jumpers JU1, JU2, and JU3 are provided to set the
operating mode of the MAX3781. Shorting these
jumpers pulls the corresponding TTL control line to a
logical zero. All TTL control lines are internally pulled
high through 15kΩ resistors. See Table 1 for more information regarding setting operating modes.
Exposed-Pad Package
The exposed paddle (EP) 48-pin TQFP has features
that provide a very low thermal resistance path for heat
removal from the IC. The paddle is electrical ground on
the MAX3781 and should be soldered to the circuit
board for proper thermal and electrical performance.
Table 1. Operating Modes
SEL_
PD
LO1_
LO2_
SO_
0
0
SI_
SI_
LI2_
0
1
−
SI_
LI2_
1
0
SI_
SI_
LI1_
1
1
SI_
−
LI1_
_______________________________________________________________________________________
MAX3781 Evaluation Kit
J23
C23
0.1µF
J30
VCC
VCC
J4
C4
0.1µF
SELB
GND
SIB+
SIBVCC
GND
9
10
11
12
VCC
GND
LO2A-
VCC
LO2A+
LO1A-
VCC
LO1A+
VCC
VCC
SIA+
SELA
PD
MAX3781
LI1BLI1B+
VCC
LI2B+
LI2B-
36
35
34
33
32
31
30
29
28
27
26
25
GND
J3
SIA-
VCC
C3
0.1µF
LI2ALI2A+
VCC
LI1A+
LI1AGND
GND
LO2B-
JU2
JU3
J28
J26
VCC
LO2B+
C2
0.1µF
GND
VCC
VCC
J2
1
2
3
4
5
6
7
8
LO1B-
R3
1kΩ
VCC
J25
CALIBRATION
STRIP
R7
100Ω
VCC VCC
LO1B+
R2
1kΩ
VCC
VCC
J1
JU1
J27
48 47 46 45 44 43 42 41 40 39 38 37
C1
0.1µF
R1
1kΩ
C19
0.1µF
R8
100Ω
R9
100Ω
C30
0.1µF
C20
0.1µF
VCC
C29
0.1µF
SOA-
C28
0.1µF
VCC
C27
0.1µF
J19
J20
C22
0.1µF
SOB-
C26
2.2µF
SOA+
C25
33µF
SOB+
J29
J21
C21
0.1µF
C24
0.1µF
VCC
L1
4.7nH
J22
Evaluates: MAX3781
J24
13 14 15 16 17 18 19 20 21 22 23 24
VCC
VCC
C18
0.1µF
J18
J17
VCC C17
0.1µF
C16
0.1µF
J16
J15
C15
0.1µF
C14
0.1µF
J14
VCC C13
0.1µF
J13 C12
0.1µF
J12
J11
C11
0.1µF
VCC
VCC
R4
100Ω
R5
100Ω
C6
0.1µF
C5
0.1µF
J5
C8
0.1µF
R6
100Ω
C9
0.1µF
C7
0.1µF
J6
J7
C10
0.1µF
J8
J9
J10
Figure 1. MAX3781 EV Kit Schematic
_______________________________________________________________________________________
3
Evaluates: MAX3781
MAX3781 Evaluation Kit
1.0"
Figure 2. MAX3781 EV Kit Component Placement Guide—Component Side
4
_______________________________________________________________________________________
MAX3781 Evaluation Kit
Evaluates: MAX3781
1.0"
1.0"
Figure 3. MAX3781 EV Kit PC Board Layout—Component Side
1.0"
Figure 4. MAX3781 EV Kit PC Board Layout—Solder Side
1.0"
Figure 5. MAX3781 EV Kit PC Board Layout—Power Plane
Figure 6. MAX3781 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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 5
© 2001 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.