Talk:Rise time

Central limit theorem
Page says: Consider a system composed by n cascaded non interacting blocks, each having a rise time t_{r_i} and no overshoot, whose input signal has a rise time t_{r_S}: then its output signal has a rise time equal to

t_{r_O}=\sqrt{t_{r_S}^2+t_{r_1}^2+\dots+t_{r_n}^2}

This result is a consequence of the central limit theorem, according to Valley & Wallman 1948, pp. 77-78. Can anyone explain why?--Light current 00:16, 7 January 2007 (UTC)

L/R ratio
I was told that rise time depends on the L/R ratio, but that is not explained in this article. Where can I find info on this? -- 99.233.186.4 (talk) 21:06, 6 February 2010 (UTC)

Rise Time
A slightly more readable form for the 0-100% rise time (via K. Ogata, Modern Control Engineering. Englewood Cliffs, NJ: Prentice-Hall, 1970) is:
 * $$ t_r \cdot\omega_0= \frac{1}{\sqrt{1-\zeta^2}}\left ( \pi - \cos^{-1}\left ( {\zeta} \right )\right )$$

In digital electronics
The article lede incorrectly states that "In ... digital electronics, these percentages are commonly the 10% and 90% (or equivalently 0.1 and 0.9) of the output step height". In fact, in digital electronics, the rise time is commonly specified as the time taken to transition from VL to VH (the low and high logic level threshold voltages, respectively) &mdash; which have nothing to do with the output step height. Lambtron (talk) 15:45, 18 April 2017 (UTC)


 * The Book "High Speed Digital Design: A Handbook of Black Magic" (Johnson and Graham) uses 10% - 90% to describe the characteristics of a digital signal as early as page 2.  — Preceding unsigned comment added by 73.131.146.228 (talk) 03:11, 13 April 2018 (UTC)


 * From Designing With Logic by Texas Instruments: "... [I]t is better to define rise and fall times over the range between VIL(max) and VIH(min), which must be adhered to in order to ensure correct functioning of the device." TI bases all subsequent discussion -- and logic device specifications -- on this commonly-used definition. Lambtron (talk) 13:27, 13 April 2018 (UTC)