Hi Team,
During the test, the customer found that the rise and fall time of the 125MHz clock output by the LMK1C1104 is long, about 1ns. Could you please help support the following requests and questions:
1. From the DS, when the clock is 156.25MHz and CL=5pF, the maximum rise and fall time is 0.8ns. Is this time related to clock frequency? Could you please test the time under the condition of 125MHz, CL=6pF with EVM and share your test data?
2. From the PCB, the distance between the buffer and the CPU is not far (but there are two vias). From the schematic, there is a 33.2Ω resistor on the trace. Is this resistor the reason for the extended rise/fall times? Is it recommended to use 0 ohm resistors?
*EC1_GTX_CLK125 is collect to CPU input pin directly.
*R9966 pin2 & CPU pinAC3 have 2vias, and the EC1_GTX_CLK125 trace on inner layer18
3. The customer's index is less than or equal to 0.8ns. Is this device a good choice? Is there any other recommendation?
Regards,
Hailiang