Hold time and Setup time (2)

So what is the real usage of Hold time and Setup Time for pin to register?

Well, I did explain in the previous post. But in detail, the Hold time is for customer who want to connect synchronously to your chip. So, if you have positive hold time for your pin to register, customer need to make sure he/she delayed the data path long enough for it to work. In this case, setup time is not important.

But how about when the customer want to connect asynchronously? Then setup time will be important. When you spec customer for 8ns setup time, you actually give yourself 8ns margin to play with. Meaning, you can delay your data path for less than 8ns before the setup time failed. How come you have that 8ns? Because based on the spec, customer will send the data first and then only send the clock after 8ns. So in your data path, you have 8ns to play around.

That's all for now kids. Stay tune!

Previous blog:
Hold time and Setup Time
Follow up blog:
Setup and speed of circuit