CY2907 Output Impedence and Series Resistance Values

Question: What is the output impedence of the CY2907 clock outputs?

 

Answer:

The output impedence for all clock outputs is: 29.5ohms for 3.3V devices 22.5ohms for 5V devices Series resistance values used to reduce reflections and match the trace impedence can be calculated by subtracting the trace impedence from the output impedence. Example: 50 ohm trace impedence and a 3.3V CY2907 device. 50ohms - 29.5ohms = 20.5ohms series resistor value