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Cables and Connectors
Interconnect for CML typically has a differential imped
-
ance of 100Ω. Use cables and connectors that have
matched differential impedance to minimize impedance
discontinuities. Coax cables typically have a characteristic
impedance of 50Ω. Contact the factory for 75Ω operation.
lists the suggested cables and connectors used
in the GMSL link.
Board Layout
Separate LVCMOS logic signals, LVDS and CML/coax
high-speed signals to prevent crosstalk. Use a four-layer
PCB with separate layers for power, ground, LVDS/CML/
coax, and LVCMOS logic signals. Layout PCB traces
close to each other for a 100Ω differential characteristic
impedance for STP. The trace dimensions depend on the
type of trace used (microstrip or stripline). Note that two
50Ω PCB traces do not have 100Ω differential impedance
when brought close together—the impedance goes down
when the traces are brought closer. Use a 50Ω trace for
the single-ended output when driving coax.
Route the PCB traces for differential LVDS/CML chan
-
nels in parallel to maintain the differential characteristic
impedance. Avoid vias. Keep PCB traces that make up
a differential pair equal length to avoid skew within the
differential pair.
ESD Protection
ESD tolerance is rated for Human Body Model, IEC
61000-4-2, and ISO 10605. The ISO 10605 and IEC
61000-4-2 standards specify ESD tolerance for electronic
systems. The serial link inputs are rated for ISO 10605
ESD protection and IEC 61000-4-2 ESD protection. All
pins are tested for the Human Body Model. The Human
Body Model discharge components are C
S
= 100pF and
R
D
= 1.5kΩ (
). The IEC 61000-4-2 discharge
components are C
S
= 150pF and R
D
= 330Ω (
).
The ISO 10605 discharge components are C
S
= 330pF
and R
D
= 2kΩ (
).
Figure 43. Human Body Model ESD Test Circuit
Figure 45. ISO 10605 Contact Discharge ESD Test Circuit
Figure 44. IEC 61000-4-2 Contact Discharge ESD Test Circuit
Table 23. Suggested Connectors and Cables for GMSL
VENDOR
CONNECTOR
CABLE
TYPE
Rosenberger
59S2AX-400A5-Y
RG174
Coax
Rosenberger
D4S10A-40ML5-Z
Dacar 535-2
STP
Nissei
GT11L-2S
F-2WME AWG28
STP
JAE
MX38-FF
A-BW-Lxxxxx
STP
STORAGE
CAPACITOR
HIGH-
VOLTAGE
DC
SOURCE
DEVICE
UNDER
TEST
CHARGE-CURRENT-
LIMIT RESISTOR
DISCHARGE
RESISTANCE
1M
Ω
R
D
1.5k
Ω
C
S
100pF
STORAGE
CAPACITOR
HIGH-
VOLTAGE
DC
SOURCE
DEVICE
UNDER
TEST
CHARGE-CURRENT-
LIMIT RESISTOR
DISCHARGE
RESISTANCE
R
D
2k
Ω
C
S
330pF
C
S
150pF
STORAGE
CAPACITOR
HIGH-
VOLTAGE
DC
SOURCE
DEVICE
UNDER
TEST
CHARGE-CURRENT-
LIMIT RESISTOR
DISCHARGE
RESISTANCE
R
D
330
Ω
MAX9277/MAX9281
3.12Gbps GMSL Serializers for Coax or
STP Output Drive and LVDS Input
www.maximintegrated.com
Maxim Integrated │
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