74AHC_AHCT240 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 4 — 25 September 2013 7 of 16
NXP Semiconductors 74AHC240; 74AHCT240
Octal buffer/line driver; inverting; 3-state
[1] Typical values are measured at nominal supply voltage (V
CC
= 3.3 V and V
CC
= 5.0 V).
[2] t
pd
is the same as t
PLH
and t
PHL
; t
en
is the same as t
PZH
and t
PZL
; 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 W).
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.
11. Waveforms
74AHCT240
t
pd
propagation delay nAn to nYn; see Figure 5
[2]
V
CC
= 4.5 V to 5.5 V; C
L
= 15 pF - 3.0 5.8 1.0 6.8 8.5 ns
V
CC
= 4.5 V to 5.5 V; C
L
= 50 pF - 4.4 8.4 1.0 9.5 11.9 ns
t
en
enable time nOE to nYn; see Figure 6
[2]
V
CC
= 4.5 V to 5.5 V; C
L
= 15 pF - 3.4 7.5 1.0 9.0 14.4 ns
V
CC
= 4.5 V to 5.5 V; C
L
= 50 pF - 4.5 9.5 1.0 11.5 14.4 ns
t
dis
disable time nOE to nYn; see Figure 6
[2]
V
CC
= 4.5 V to 5.5 V; C
L
= 15 pF - 3.9 6.1 1.0 6.7 8.3 ns
V
CC
= 4.5 V to 5.5 V; C
L
= 50 pF - 6.2 8.7 1.0 9.2 11.5 ns
C
PD
power dissipation
capacitance
V
I
= GND to V
CC
; C
L
=50pF;
f
i
=1MHz
[3]
-9-- - -pF
Table 7. Dynamic characteristics
…continued
Voltages are referenced to GND (ground = 0 V); for test circuit see Figure 7.
Symbol Parameter Conditions 25 C 40 C to +125 C Unit
Min Typ
[1]
Max Min Max
(85 C)
Max
(125 C)
Measurement points are given in Table 8.
V
OL
and V
OH
are typical voltage output drop that occur with the output load.
Fig 5. Propagation delay input (nAn) to output (nYn)
nAn input
nYn output
t
PHL
t
PLH
GND
V
I
V
M
V
M
V
M
V
M
V
OH
V
OL
90 %
10 % 10 %
90 %
t
THL
t
TLH
mgu781
