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Philips Semiconductors
Product specification
74LV161
Presettable synchronous 4-bit binary counter;
asynchronous reset
2
1997 May 15
853–1917 18039
FEATURES
Optimized for low voltage applications: 1.0 to 3.6 V
Accepts TTL input levels between V
CC
= 2.7 V and V
CC
= 3.6 V
Typical V
OLP
(output ground bounce) < 0.8 V at V
CC
= 3.3 V,
T
amb
= 25
°
C
Typical V
OHV
(output V
OH
undershoot) > 2 V at V
CC
= 3.3 V,
T
amb
= 25
°
C
Asynchronous reset
Synchronous counting and loading
Two count enable inputs for n-bit cascading
Positive-edge triggered clock
Output capability: standard
I
CC
category: MSI
DESCRIPTION
The 74LV161 is a low-voltage Si-gate CMOS device and is pin and
function compatible with 74HC/HCT161.
The 74LV161 is a synchronous presettable binary counter which
features an internal look-head 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 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 cascading 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
tp
(max)
(CP to TC)
t
su
(CEP to CP)
f
max
QUICK REFERENCE DATA
GND = 0 V; T
amb
= 25
°
C; t
r
= t
f
≤
2.5 ns
SYMBOL
PARAMETER
CONDITIONS
TYPICAL
UNIT
t
PHL
/t
PLH
Propagation delay
CP to Q
n
CP to TC
MR to Q
n
MR to TC
CET to TC
C
L
= 15 pF;
V
CC
= 3.3 V
15
18
15
17
9
ns
f
max
C
I
C
PD
NOTES:
1. C
PD
is used to determine the dynamic power dissipation (P
D
in
μ
W)
P
D
= C
PD
V
CC2
f
i
(C
L
f
i
= input frequency in MHz; C
L
= output load capacity in pF;
f
o
= output frequency in MHz; V
CC
= supply voltage in V;
(C
L
V
CC2
f
o
) = sum of the outputs.
Maximum clock frequency
77
MHz
Input capacitance
3.5
pF
Power dissipation capacitance per gate
V
I
= GND to V
CC1
25
pF
V
CC2
f
o
) where:
ORDERING INFORMATION
PACKAGES
TEMPERATURE RANGE
OUTSIDE NORTH AMERICA
NORTH AMERICA
PKG. DWG. #
16-Pin Plastic DIL
–40
°
C to +125
°
C
74LV161 N
74LV161 N
SOT38-4
16-Pin Plastic SO
–40
°
C to +125
°
C
74LV161 D
74LV161 D
SOT109-1
16-Pin Plastic SSOP Type II
–40
°
C to +125
°
C
74LV161 DB
74LV161 DB
SOT338-1
16-Pin Plastic TSSOP Type I
–40
°
C to +125
°
C
74LV161 PW
74LV161PW DH
SOT403-1