74ALVC245_2 © NXP B.V. 2008. All rights reserved.
Product data sheet Rev. 02 — 7 January 2008 6 of 14
NXP Semiconductors
74ALVC245
Octal bus transceiver; 3-state
10. Dynamic characteristics
[1] All typical values are measured at T
amb
= 25 °C and V
CC
= 1.8 V, 2.5 V, 2.7 V and 3.3 V.
[2] t
pd
is the same as t
PLH
and t
PHL
.
t
en
is the same as t
PZL
and t
PZH
.
t
dis
is the same as t
PLZ
and t
PHZ
.
[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+Σ(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;
Σ(C
L
× V
CC
2
× f
o
) = sum of the outputs.
Table 7. Dynamic characteristics
Voltages are referenced to GND (ground = 0 V); for test circuit see Figure 7.
Symbol Parameter Conditions −40 °C to +85 °C Unit
Min Typ
[1]
Max
t
pd
propagation delay An to Bn; Bn to An; see Figure 5
[2]
V
CC
= 1.65 V to 1.95 V 1.0 2.7 6.0 ns
V
CC
= 2.3 V to 2.7 V 1.0 2.1 3.5 ns
V
CC
= 2.7 V 1.0 3.0 3.6 ns
V
CC
= 3.0 V to 3.6 V 1.0 2.3 3.4 ns
t
en
enable time OE to An; OE to Bn; see Figure 6
[2]
V
CC
= 1.65 V to 1.95 V 1.0 4.0 8.6 ns
V
CC
= 2.3 V to 2.7 V 1.0 3.0 6.0 ns
V
CC
= 2.7 V 1.0 2.6 6.3 ns
V
CC
= 3.0 V to 3.6 V 1.0 2.9 5.5 ns
t
dis
disable time OE to An; OE to Bn; see Figure 6
[2]
V
CC
= 1.65 V to 1.95 V 1.0 4.4 8.0 ns
V
CC
= 2.3 V to 2.7 V 1.0 2.3 4.8 ns
V
CC
= 2.7 V 1.0 3.3 5.3 ns
V
CC
= 3.0 V to 3.6 V 1.0 3.2 5.5 ns
C
PD
power dissipation
capacitance
per buffer; V
I
= GND to V
CC
;V
CC
= 3.3 V
[3]
outputs enabled - 25 - pF
outputs disabled - 1 - pF
