Texas Instruments LMK61E2EVM, User Manual

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OUT_P
0.1µF
C25
0.1µF
C24
0
R25
0
R28
OUT_N
R_OUT_P
R_OUT_N
1
2 3 4 5
P2
OUTP
1
2 3 4 5
P3
OUTN
0
R27
100
R31
0
R30
150
R26
150
R29
Configuring the Clock Output
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6 Configuring the Clock Output
The LMK61E2’s differential output is routed via 50 ohm single ended traces to SMA ports (OUTN and
OUTP) through AC coupling capacitors. The output also has a series resistor (0 ohm populated by default,
R25 ad R28) and emitter resistors (150 ohm populated by default for LVPECL, R26 and R29). Common
output format terminations are shown in Table 4. The output termination schematic is shown in
Figure 5 .
Table 4. Output Termination Schemes
OUTPUT FORMAT COUPLING COMPONENT VALUE
LVPECL AC R25, R28 0 Ω
(default EVM
R26, R29 150 Ω
configuration)
C24, C25 0.01 uF
R27, R30, R31 DNP
DC
(1)
R25, R28, C24, C25 0 Ω
R26, R27, R29, R30, R31 DNP
LVDS
(2)
AC R25, R27, R28, R30 0 Ω
R31 100
Ω
C24, C25 0.01 uF
R26, R29 DNP
DC R25, R27, R28, R30, C24, C25 0 Ω
R31 100 Ω
HCSL AC R25, R28 0
Ω
(22
Ω
optional)
R26, R29 50 Ω
C24, C25 0 Ω
R27, R30, R31 DNP
DC R25, R28 0 Ω (22 Ω optional)
R26, R29 50
Ω
C24, C25 0.01 uF
R27, R30, R31 DNP
(1)
50 ohm to Vcc-2 V termination is required on receiver.
(2)
100 ohm differential termination (R31) is provided on the LMK61E2EVM. Removing the differential termination on the EVM is
possible if the differential termination is available on the receiver.
Figure 5. LMK61E2EVM Termination Schematic
10 LMK61E2EVM User's Guide SNAU188 – October 2015
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