The 74HC161 is a synchronous presettable binary counter with an internal look-ahead carry.
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 may be preset HIGH or LOW.
A LOW at the parallel enable input (PE) disables the counting action and causes the data at theย data inputs (D0 to D3) to be loaded into the counter on the positive-going edge of the clock. Preset
takes place regardless of the levels at count enable inputs (CEP and CET). A LOW at the masterย reset input (MR) sets Q0 to Q3 LOW regardless of the levels at input pins CP, PE, CET and CEP
(thus providing an asynchronous clear function).
The look-ahead carry simplifies serial cascadingย of the counters. Both CEP and CET must be HIGH to count. The CET input is fed forward to enableย the terminal count output (TC). The TC output thus enabled will produce a HIGH output pulse of aย duration approximately equal to a HIGH output of Q0. This pulse can be used to enable the nextย cascaded stage. The maximum clock frequency for the cascaded counters is determined by the CPย to TC propagation delay and CEP to CP set-up time.
Inputs include clamp diodes. This enables the use of current limiting resistors to interface inputs toย voltages in excess of VCC.
Features:
- Complies with JEDEC standard no. 7A
- CMOS input levels
- Synchronous counting and loading
- Two count enable inputs for n-bit cascading
- Asynchronous reset
- Positive-edge triggered clock
- ESD protection:
- HBM JESD22-A114F exceeds 2000 V
- MM JESD22-A115-A exceeds 200 V
- Multiple package options
- Specified from -40 ยฐC to +85 ยฐC and -40 ยฐC to +125 ยฐC
Applications:
- Presettable synchronous 4 bit binary counter
DataSheet:
Package Includes:
- 1 xย 74hc161 ICย
ย
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