INTEGRATED CIRCUITS
DATA SHEET
For a complete data sheet, please also download:
•
The IC06 74HC/HCT/HCU/HCMOS Logic Family Specifications
•
The IC06 74HC/HCT/HCU/HCMOS Logic Package Information
•
The IC06 74HC/HCT/HCU/HCMOS Logic Package Outlines
74HC/HCT161
Presettable synchronous 4-bit
binary counter; asynchronous reset
Product specification
File under Integrated Circuits, IC06
December 1990
Philips Semiconductors
Product specification
Presettable synchronous 4-bit binary
counter; asynchronous reset
FEATURES
•
Synchronous counting and loading
•
Two count enable inputs for n-bit cascading
•
Positive-edge triggered clock
•
Asynchronous reset
•
Output capability: standard
•
I
CC
category: MSI
GENERAL DESCRIPTION
The 74HC/HCT161 are high-speed Si-gate CMOS devices
and are pin compatible with low power Schottky TTL
(LSTTL). They are specified in compliance with JEDEC
standard no. 7A.
The 74HC/HCT161 are synchronous presettable binary
counters which feature an internal look-ahead carry and
can be used for high-speed counting.
Synchronous operation is provided by having all flip-flops
clocked simultaneously on the positive-going edge of the
clock (CP).
The outputs (Q
0
to Q
3
) of the counters may be preset to a
HIGH or LOW level. A LOW level at the parallel enable
74HC/HCT161
input (PE) disables the counting action and causes the
data at the data inputs (D
0
to D
3
) to be loaded into the
counter on the positive-going edge of the clock (providing
that the set-up and hold time requirements for PE are met).
Preset takes place regardless of the levels at count enable
inputs (CEP and CET).
A LOW level at the master reset input (MR) sets all four
outputs of the flip-flops (Q
0
to Q
3
) to LOW level regardless
of the levels at CP, PE, CET and CEP inputs (thus
providing an asynchronous clear function).
The look-ahead carry simplifies serial cascading of the
counters. Both count enable inputs (CEP and CET) must
be HIGH to count. The CET input is fed forward to enable
the terminal count output (TC). The TC output thus
enabled will produce a HIGH output pulse of a duration
approximately equal to a HIGH level output of Q
0
. This
pulse can be used to enable the next cascaded stage.
The maximum clock frequency for the cascaded counters
is determined by the CP to TC propagation delay and CEP
to CP set-up time, according to the following formula:
1
-
f
max
= --------------------------------------------------------------------------------------------------
t
P(max)
(CP to TC)
+
t
SU
(CEP to CP)
QUICK REFERENCE DATA
GND = 0 V; T
amb
= 25
°C;
t
r
= t
f
= 6 ns
TYPICAL
SYMBOL PARAMETER
t
PHL
/ t
PLH
propagation delay
CP to Q
n
CP to TC
MR to Q
n
MR to TC
CET to TC
maximum clock frequency
input capacitance
power dissipation
capacitance per package
notes 1 and 2
CONDITIONS
HC
C
L
= 15 pF;
V
CC
= 5 V
19
21
20
20
10
44
3.5
33
HCT
20
24
25
26
14
45
3.5
35
ns
ns
ns
ns
ns
MHz
pF
pF
UNIT
Notes
1. C
PD
is used to determine the
dynamic power dissipation
(P
D
in
µW):
P
D
= C
PD
×
V
CC2
×
f
i
+
∑
(C
L
×
V
CC2
×
f
o
)
where:
f
i
= input frequency in MHz
f
o
= output frequency in MHz
∑
(C
L
×
V
CC2
×
f
o
) = sum of
outputs
C
L
= output load capacitance in
pF
V
CC
= supply voltage in V
2. For HC the condition is
V
I
= GND to V
CC
For HCT the condition is
V
I
= GND to V
CC
−
1.5 V
f
max
C
I
C
PD
December 1990
2
Philips Semiconductors
Product specification
Presettable synchronous 4-bit binary
counter; asynchronous reset
74HC/HCT161
Fig.4 Functional diagram.
FUNCTION TABLE
INPUTS
OPERATING MODE
MR
reset (clear)
parallel load
count
hold
(do nothing)
Note
1. The TC output is HIGH when CET is HIGH and the counter is at terminal count (HHHH).
H = HIGH voltage level
h = HIGH voltage level one set-up time prior to the LOW-to-HIGH CP transition
L = LOW voltage level
I = LOW voltage level one set-up time prior to the LOW-to-HIGH CP transition
q = lower case letters indicate the state of the referenced output one set-up time prior to the
LOW-to-HIGH CP transition
X = don’t care
↑
= LOW-to-HIGH CP transition
L
H
H
H
H
H
X
↑
↑
↑
X
X
CP
X
X
X
h
I
X
CEP
X
X
X
h
X
I
CET
X
I
I
h
h
h
PE
X
I
h
X
X
X
D
n
L
L
H
count
q
n
q
n
Q
n
L
L
(1)
(1)
(1)
OUTPUTS
TC
L
December 1990
4
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