The XO input of the LMK5B33414 has programmable on-chip input termination and AC-coupled input biasing
options to support any clock interface type.
Jumpers to power onboard TCXO:
The onboard TCXO can be powered in
three manners:
1. Direct 3.3-V supply provided to VIN3.
Tie pins 5-6 (adjacent to JP4 designator).
2. 3.3-V supply provided from output of
LDO3 (U9). Tie pins 3-4.
3. 3.3-V supply provided from output of
DCDC1 (U500). Tie pins 1-2 (opposite to
JP4 designator).
Remove jumper from JP4 when
providing external XO input.
External XO Input
Onboard 48 MHz
TCXO
Rework required to
select between
onboard XO/TCXO
(default) or
external SMA XO_p
Figure 3-9. XO Input
3.5.1 48-MHz TCXO (Default)
By default, the EVM is populated with a 48-MHz, 3.3-V LVCMOS, low-jitter TCXO, designated as Y1 (3.2 mm
× 2.5 mm), which drives the XO input of the LMK5B33414 with the onboard termination and AC coupling. See
. All LMK5B33414 EVMs have a TXC 7N48071001 48-MHz TCXO populated on Y1. Y1 can be used
to evaluate various frequency configurations.
3.5.2 External Clock Input
Another option is to feed an external clock to the XO SMA port (J8) to drive the XO input. See
. This
path can be connected to the XO input pins. Y1 should be powered down when using the external XO input
path. To power down Y1 and use an external XO input, the jumper on JP4 must be removed. Recommended XO
frequencies for best device performance are frequencies of 10, 13, 14.4, 19.44, 24, 25, 27, 38.88, and 48 MHz.
EVM Configuration
12
LMK5B33414EVM User's Guide
SNAU279 – JULY 2022
Copyright © 2022 Texas Instruments Incorporated
