XC7SH14_1 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 01 — 1 September 2009 8 of 14
NXP Semiconductors
XC7SH14
Inverting Schmitt trigger
14. Application information
The slow input rise and fall times cause additional power dissipation, which 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 (µW);
f
i
= input frequency (MHz);
t
r
= input rise time (ns); 10 % to 90 %;
t
f
= input fall time (ns); 90 % to 10 %;
∆I
CC(AV)
= average additional supply current (µA).
Average additional I
CC
differs with positive or negative input transitions, as shown in
Figure 12.
For XC7SH14 used in relaxation oscillator circuit, see Figure 13.
Note to the application information:
1. All values given are typical unless otherwise specified.
V
CC
= 5.5 V.
Fig 11. Typical transfer characteristics
02 6
8
0
2
4
6
mna403
4
V
I
(V)
I
CC
(mA)
