Hi,
I have a project where one of the output signals is a short pulse with a width of 100ns and repeat frequency of 1MHz. The main clock in my design is
20MHz. After I download the program to the chip (EPM7128SLC-7) severe overshoots (over 2V @VCC=5V)can be observed. Does anybody know an answer to this problem? Thank you.-- Regards, Jian
Uzytkownik "Jian Ju" napisal w wiadomosci news:1069903547.946685@hkpu01...
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A serial inductance at the power path can do the overshoots or a switching power supply generates pulses of voltage at times where large current changes are observed (shortcut to ground or VCC at output pin).
Regards, krzysiek
Hi Jian,
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This could be due to ground bounce or a badly matching trace impedance. I suggest that you turn on the 'Slow Slew rate' for this pin. It will make the level transitions of the pin slower by about 1ns (it's a bit asymmetrical) so that the device doesn't 'pull as hard' on the line.
If that doesn't help, get back to us.
Best regards,
Ben
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