74HC74 Dual D-Type Flip-Flop with Set and Reset; Positive Edge-Trigger

The 74HC74 designed as a dual positive edge-triggered D-type flip-flop. The 74HC74 consists of dual positive-edge triggered, D-type flip-flops with individual data (D) inputs, clock (CP) inputs, set (SD) and reset (RD) inputs; also complementary Q and Q outputs. The Data at the D-input, that meets the set-up and hold time requirements on the LOW-to-HIGH clock transition, stored in the flip-flop and appears at the Q output. Schmitt-trigger function in the clock input, makes the circuit highly tolerant to slower clock rise and fall times. Whereas the Inputs include clamp diodes that enable the use of current limiting resistors to interface inputs to voltages in excess of VCC.

The 74HC/HCT74 is a high-speed Si-gate CMOS device and is pin compatible with low power Schottky TTL
(LSTTL). They are specified in compliance with JEDEC standard no. 7A.  The D flip-flop is an edge triggered device which transfers input data to Q on clock rising or falling edge. Data Latches are level sensitive devices such as the data latch and the transparent latch.

The 74HC74 (7474) integrated circuit provides two independent D-type flip flops in a single package. The flip flop triggered on the positive edge of a clock pulse. At the moment the clock pin (CLK) goes high, the state of data pin (D)captured and held as output (Q). Q will not change again until the next time the clock rises, regardless of how long the clock stays high, or any further changes to D.