Features: · Synchronous counting and loading
· Two count enable inputs for n-bit cascading
· Positive-edge triggered clock
· Asynchronous reset
· Output capability: standard
· ICC category: MSIPinout
DescriptionThe 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 (Q0 to Q3) of the counters of the 74HC/HCT160 may be preset to aHIGH 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 for PE are met).Preset takes place regardless of the levels at count enableinputs (CEP and CET).
A LOW level at the master reset input (MR) of the 74HC/HCT160 sets all fouroutputs of the flip-flops (Q0 to Q3) to LOW level regardlessof the levels at CP, PE, CET and CEP inputs (thusproviding an asynchronous clear function).
The look-ahead carry simplifies serial cascading of thecounters. 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 of the 74HC/HCT160 for the cascaded countersis determined by the CP to TC propagation delay and CEP to CP set-up time, according to the following formula.
74HC/HCT160 Data Sheet
