Dear Ianp,
Let said the microcontroller Vcc is 5V +/-10% (4.5V~5.5V). So, in this case we should choose 4.38V +/-3% (4.2486V~4.5114V). If the Vcc is lower than 4.5V the reset will active for ≈240ms, am i rite? If yes, how bout if the Vcc is below than 4.25V, what will happen?
In the datasheet said:
The 4.63V and 3.08V options of the LM809/810 use highly accurate circuitry to ensure that the reset threshold occurs only within this range (for 5V and 3.3V
supplies).
So, if we choose 4.63 +/- 3% mean our Vcc must be stable otherwise the reset will alway active?
Thank you,.