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Why are reset function time and electrical section different?"

Latest Updated:04/01/2006

Question:

The electrical specifications section in the data sheet indicates that the oscillation stabilization time when using a ceramic resonator is 4 ms.
However, the reset function explanation says, "after the oscillation stabilization time has elapsed (2 17/fx)".
Why are these times different?

Answer:

The value in the electrical specifications prescribes the characteristics of the oscillator.
In other words, as long as there is matching, when using a ceramic resonator, oscillation of the internal oscillator will stabilize within 4 ms.
On the other hand, 2 17/fx applies to the microcontroller as a whole and indicates the time required for oscillation to stabilize before the CPU can start operating.
If this value is longer than the actual stabilization time of the oscillator, the clock oscillation is already stable by the time the CPU starts operating, so there is no possibility of malfunction due to the oscillation stabilization time.
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