December 1990 2
Philips Semiconductors Product specification
Presettable synchronous BCD decade 
counter; asynchronous reset
74HC/HCT160
FEATURES
• Synchronous counting and loading
• Two count enable inputs for n-bit cascading
• Positive-edge triggered clock
• Asynchronous reset
• Output capability: standard
• ICC category: MSI
GENERAL DESCRIPTION
The 74HC/HCT160 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/HCT160 are synchronous presettable decade 
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 Q3) 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 (D0 to D3) to be loaded into the 
counter on the positive-going edge of the clock (providing 
that the set-up and hold time requirements forPE 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 (Q0 to Q3) 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 Q0. 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:
f
max
=
1
t
P max()
CP to TC()+tSU(CEP to CP)
---------------------------------------------------------------------------------------------------------
QUICK REFERENCE DATA
GND = 0 V; T
amb
=25°C; tr=tf= 6 ns
SYMBOL PARAMETER CONDITIONS
TYPICAL
UNIT
HC HCT
t
PHL
propagation delay
CP to Q
n
CP to TC 
MR to Q
n
MR to TC 
CET to TC
CL=15pF; 
VCC=5V 19
21 
21 
21 
14
21 
24 
23 
26 
14
ns 
ns 
ns 
ns 
ns
t
PLH
propagation delay
CP to Q
n
CP to TC 
CET to TC
19 
21 
14
21 
20 
7
ns 
ns 
ns
f
max
maximum clock 
frequency
61 31 MHz
C
I
input capacitance 3.5 3.5 pF
C
PD
power dissipation 
capacitance per 
package
notes 1 and 2
39 34 pF
Notes
1. CPD is used to determine the 
dynamic power dissipation 
(PD in µW):
PD=CPD× V
CC
2
× fi+
∑ (CL× V
CC
2
 × fo)
where:
fi= input frequency in MHz 
fo= output frequency in MHz 
∑ (CL× V
CC
2
× fo) = sum of 
outputs 
CL= output load capacitance in 
pF 
VCC= supply voltage in V
2. For HC the condition is 
VI= GND to V
CC
For HCT the condition is
VI= GND to VCC− 1.5 V