setup time & hold time

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ku637

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Hi,
I'm just referring a processor datasheet.It is a 33MHz rated part.
The AC Characteristics for 33MHz part tell CLK can be from 8MHz to 33MHz
And is further specifying databus setup time as 5ns minimum.

I have doubt if i provide the processor with 12MHz clock will the setup time spec vary..?


May be I'm asking a silly question.But can anyone clarify?

Thanks,

Regards,
 

Hi,

the setup time usually is independent of the actual clock frequency.

Klaus
 

The question isn't silly but rather vague. Which data bus setup time are you specifically talking about? Between which bus signals?
 

The setup time defines the time before a rising edge of the clock (usually rising) the data (bus, control signal, etc) has to be stable. As it is an inherent property of the capture register that is being clocked it does not change when the clock frequency changes. What it does do is define the maximum frequency that the device can operate at.

Many CMOS devices can be clocked even at 1 Hz without a problem. I imagine the 8 MHz of this uC is probably related to the minimum frequency you can achieve with the built in clock circuit.
 

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