1uS wide pulse signal

呜呼哀哉

1uS wide pulse signal [Copy link]

Dear forum friends, there is a need to generate a 1us high-level TTL periodic signal recently. The microcontroller can achieve this 1uS high-level excitation, but I am worried about what problems will occur during PCB design. This 1us signal has a rise time of about 10ns, which is only 35MHZ based on the bandwidth. According to the 2inch/1ns terminal matching requirement, my routing is within 1inch and nothing is needed. There should be no problems. Maybe I have been too unlucky recently and I am a little nervous. I always feel that there will be problems there, but I haven't considered it. Please help me think about where the problem may occur. Do I need to ensure the characteristic impedance of the routing?

grateful

qwqwqw2088

Don't worry too much, you can do a sample test first

1 inch is not too long. Impedance matching has been considered. The line width does not change. No holes are drilled in the routing line. The impedance will not change much.

In addition, the appropriate copper thickness and the dielectric constant of the general board should be guaranteed.

tagetage

1us, no problem.

btty038

Just do it casually, don't worry too much, don't be too deliberate, just follow the normal rules and it's done

呜呼哀哉

Thanks for the help, open.

LeoMe

PP output 35M should be OK. I think unless the PCB line is very long, the parasitic capacitance and inductance are very large, there is no need to worry about the rising edge problem, and the driving force is full. What you should worry about is the overshoot ringing of the jump edge.

w494143467

I think there should be no problem. I can capture 20 to 30M clock waves using Dupont cables. There must be no problem with the routing on your board!