74HC14 Datasheet, PDF (8/8 Pages) NXP Semiconductors – Hex inverting Schmitt trigger

Philips Semiconductors
Hex inverting Schmitt trigger
APPLICATION INFORMATION
The slow input rise and fall times cause additional power
dissipation, this can be calculated using the following
formula:
P_ad = f_i × (t_r × I_CCa + t_f × I_CCa) × V_CC.
Where:
P_ad = additional power dissipation (µW)
f_i
= input frequency (MHz)
t_r
= input rise time (µs); 10% − 90%
t_f
= input fall time (µs); 10% − 90%
I_CCa = average additional supply current (µA)
Average I_CCa differs with positive or negative input
transitions, as shown in Figs 14 and 15.
Product specification
74HC/HCT14
Fig.14 Average I_CC for HC Schmitt trigger devices;
linear change of V_i between 0.1 V_CC to
0.9 V_CC
HC/HCT14 used in a relaxation oscillator circuit, see
Fig.16.
HC : f = _T-1-- ≈ _{0----.--8--1---R----C---}
HCT : f = _T-1-- ≈ _{0----.-6----7-1----R-----C--}
Fig.16 Relaxation oscillator using HC/HCT14.
Fig.15 Average I_CC for HCT Schmitt trigger devices;
linear change of V_i between 0.1 V_CC to
0.9 V_CC.
Note to Application information
All values given are typical unless otherwise specified.
PACKAGE OUTLINES
See “74HC/HCT/HCU/HCMOS Logic Package Outlines”.
September 1993
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