CD74AC161中文资料具有异步复位的同步可预设的二进制计数器数据手册TI规格书

描述 Description

The ’AC161 devices are 4-bit binary counters. These synchronous, presettable counters feature an internal carry look-ahead for application in high-speed counting These devices are fully programmable; that is, they can be preset to any number between 0 and 9 or 15. Presetting is synchronous; therefore, setting up a low level at the load input disables the counter and causes the outputs to agree with the setup data after the next clock pulse, regardless of the levels of the enable inputs.

The clear function is asynchronous. A low level at the clear (CLR)\\ input sets all four of the flip-flop outputs low, regardless of the levels of the CLK, load (LOAD)\\, or enable inputs.

The carry look-ahead circuitry provides for cascading counters for n-bit synchronous applications without additional gating. Instrumental in accomplishing this function are ENP, ENT, and a ripple-carry output (RCO). Both ENP and ENT must be high to count, and ENT is fed forward to enable RCO. Enabling RCO produces a high-level pulse while the count is maximum (9 or 15 with QA high). This high-level overflow ripple-carry pulse can be used to enable successive cascaded stages. Transitions at ENP or ENT are allowed, regardless of the level of CLK.

The counters feature a fully independent clock circuit. Changes at control inputs (ENP, ENT, or LOAD\\) that modify the operating mode have no effect on the contents of the counter until clocking occurs. The function of the counter (whether enabled, disabled, loading, or counting) is dictated solely by the conditions meeting the stable setup and hold times.

特性 Features

• Internal Look-Ahead for Fast Counting
• Carry Output for n-Bit Cascading
• Synchronous Counting
• Synchronously Programmable
• SCR-Latchup-Resistant CMOS Process and Circuit Design
• Exceeds 2-kV ESD Protection per MIL-STD-883, Method 3015

简介

CD74AC161属于集成电路（IC）的计数器除法器。由TI制造生产的CD74AC161计数器，除法器计数器和除法器 IC 是数字逻辑器件，可对输入发生的逻辑转换进行计数，然后使用多个并行输出重新发送累加的计数，和/或生成单个输出信号转换，从而对应用某些整数数量输入信号转换进行响应。除了简单的事件计数，它们还可用于各种频率合成应用。