312.5 MHz fixed-frequency XO for SerDes reference clocks
The LMK61A2-312M50SIAT is a fixed-frequency clock oscillator from Texas Instruments' LMK61A2 family, delivering a 312.5 MHz output from a 6-SMD module (6-QFM, 7x5 mm footprint). This frequency aligns with the standard reference clock for 10 GbE and 25 GbE SerDes PLLs, making it a direct drop-in for Ethernet PHY and FPGA transceiver reference designs. Operating from a 3.135 V to 3.465 V supply rail, it draws 152 mA typical.
Supply and temperature envelope for board-level integration
The supply voltage tolerance of ±5% around the nominal 3.3 V rail means this oscillator can share a common 3.3 V plane with other digital logic without requiring a dedicated LDO. The 152 mA supply current is the total drawn from that rail — budget this into the power tree alongside the FPGA core and I/O rails. The 6-QFM package (7x5 mm) has an exposed thermal pad on the bottom. For reliable heat transfer into the PCB, the layout should include a thermal via array under the pad connected to an internal ground plane. The part is surface-mount and reflow-compatible with standard lead-free profiles.