Datasheet

74HC21_5 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 05 — 7 May 2009 5 of 14
NXP Semiconductors
74HC21
Dual 4-input AND gate
10. Dynamic characteristics
[1] t
pd
is the same as t
PHL
and t
PLH
.
[2] t
t
is the same as t
THL
and t
TLH
.
[3] C
PD
is used to determine the dynamic power dissipation (P
D
in µW):
P
D
=C
PD
× V
CC
2
× f
i
× N+∑ (C
L
× V
CC
2
× f
o
) where:
f
i
= input frequency in MHz;
f
o
= output frequency in MHz;
C
L
= output load capacitance in pF;
V
CC
= supply voltage in V;
N = number of inputs switching;
∑ (C
L
× V
CC
2
× f
o
) = sum of outputs.
Table 7. Dynamic characteristics
GND = 0 V; test circuit see Figure 8.
Symbol Parameter Conditions 25 °C −40 °C to +85 °C −40 °C to +125 °C Unit
Min Typ Max Min Max Min Max
t
pd
propagation
delay
nA, nB, nC or nD to nY;
see
Figure 7
[1]
V
CC
= 2.0 V - 33 110 - 140 - 165 ns
V
CC
= 4.5 V - 12 22 - 28 - 33 ns
V
CC
= 6.0 V - 10 19 - 24 - 28 ns
V
CC
= 5.0 V; C
L
=15pF-10-----ns
t
t
transition time nY output; see Figure 7
[2]
V
CC
= 2.0 V - 19 75 - 95 - 110 ns
V
CC
= 4.5 V - 7 15 - 19 - 22 ns
V
CC
= 6.0 V - 6 13 - 16 - 19 ns
C
PD
power
dissipation
capacitance
V
I
= GND to V
CC
[3]
-15-----pF