SPRUJ09D March 2022 – September 2023 AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1 , AM263P4 , AM263P4-Q1
The AM263x SoC requires a 25-MHz clock input for XTAL_XI. All reference clocks required for the SoC and the three Ethernet PHY's are generated from a single four output clock buffer (LMK1C1104PWR), which is sourced from a single 25-MHz LVCMOS Oscillator by default. A clock buffer is used for level translation from 3.3 V to 1.8 V.
The Control Card also requires a 16-MHz clock source for the TM4C129 microcontroller for UART-USB JTAG support.
Alternatively, the SoC clock input can be sourced from a single 25-MHz crystal. To use the crystal there must be resistors mounted and unmounted. When the Crystal is used as a clock source then the AM263x CLKOUT0 signal is used to source the four output clock buffer for the Ethernet PHY reference clock signals.
The following table describes the proper resistors to be mounted and DNI'd in order for each clock source configuration.
Clock Source | Mounted | DNI |
---|---|---|
25-MHz LVCMOS Oscillator (default) | R161, R135 | R158, R155, R134 |
25-MHz Crystal | R158, R155, R134 | R161, R135 |