74HCT163DB集成電路（IC）的計數(shù)器除法器規(guī)格書PDF中文資料

1. General description

The 74HC163; 74HCT163 is a synchronous presettable binary counter with an internal look-head

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 to

a HIGH or LOW. A LOW at the parallel enable input (PE) disables the counting action. It causes

the data at the 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 master reset input (MR) sets Q0 to Q3 LOW after the next positive-going transition

on the clock input (CP). This action occurs regardless of the levels at input pins PE, CET and

CEP. This synchronous reset feature enables the designer to modify the maximum count with

only one external NAND gate. The look-ahead carry simplifies serial cascading of the counters.

Both 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 output of Q0. This pulse can be used to enable the next cascaded

stage. Inputs include clamp diodes. This enables the use of current limiting resistors to interface

inputs to voltages in excess of VCC.

The CP to TC propagation delay and CEP to CP set-up time determine the maximum clock

frequency for the cascaded counters according to the following formula:

2. Features and benefits

? Complies with JEDEC standard no. 7A

? Input levels:

? For 74HC163: CMOS level

? For 74HCT163: TTL level

? Synchronous counting and loading

? 2 count enable inputs for n-bit cascading

? Synchronous reset

? Positive-edge triggered clock

? ESD protection:

? HBM JESD22-A114F exceeds 2 000 V

? MM JESD22-A115-A exceeds 200 V

? Multiple package options

? Specified from -40 °C to +85 °C and -40 °C to +125 °C