SN74HCT74DRE4集成电路（IC）的触发器规格书PDF中文资料

SN74HCT74DRE4属于集成电路（IC）的触发器。由德州仪器制造生产的SN74HCT74DRE4触发器触发器是能够存储单个逻辑状态或信息“位”的基本数字存储器件。这些器件至少有两个输入；一个或多个用于传递要存储的数据，另一个用于指示存储该数据的时间点。不同的触发器类型，例如 D（延迟）、SR（置位复位）和 JK，对提供给其输入的信号有不同的响应，可用于实现不同的逻辑功能。这些器件与锁存器的不同之处在于它们是边缘敏感器件，其保持的逻辑状态仅在接收到有效时钟信号时才会改变。

1 Features

• Operating voltage range of 4.5 V to 5.5 V

• Outputs can drive up to 10 LSTTL loads

• Low power consumption, 40-μA max ICC

• Typical tpd = 17 ns

• ±4-mA output drive at 5 V

• Low input current of 1 μA max

• Inputs are TTL-voltage compatible

2 Description

The ’HCT74 devices contain two independent D-type

positive-edge-triggered flip-flops. A low level at the

preset (PRE) or clear (CLR) inputs sets or resets the

outputs, regardless of the levels of the other inputs.

When PRE and CLR are inactive (high), data at the

data (D) input meeting the setup time requirements

are transferred to the outputs on the positive-going

edge of the clock (CLK) pulse. Clock triggering occurs

at a voltage level and is not directly related to the

rise time of CLK. Following the hold-time interval, data

at the D input may be changed without affecting the

levels at the outputs.