74HC_HCT14 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2012. All rights reserved.
Product data sheet Rev. 6 — 19 September 2012 10 of 21
NXP Semiconductors
74HC14; 74HCT14
Hex inverting Schmitt trigger
15. Application information
The slow input rise and fall times cause additional power dissipation, this can be
calculated using the following formula:
P
add
=f
i
(t
r
I
CC(AV)
+t
f
I
CC(AV)
) V
CC
where:
P
add
= additional power dissipation (W);
f
i
= input frequency (MHz);
t
r
=rise time (ns); 10%to90%;
t
f
= fall time (ns); 90 % to 10 %;
I
CC(AV)
= average additional supply current (A).
Average I
CC(AV)
differs with positive or negative input transitions, as shown in Figure 12
and Figure 13
.
An example of a relaxation circuit using the 74HC14; 74HCT14 is shown in Figure 14
.
a. V
CC
=4.5V b. V
CC
=5.5V
Fig 11. Typical 74HCT transfer characteristics
05
1.5
0
0.3
0.6
0.9
1.2
1234
mna849
I
CC
(mA)
V
I
(V)
0123 6
1.8
0
0.6
0.3
1.2
1.5
0.9
45
mna850
I
CC
(mA)
V
I
(V)
