Flip-Flops and Latches

Flip-flops are a useful type of digital device that can store binary states, or be used as a sort of digital toggle switch. The flip-flop is a digital device, so its output (labeled with a Q in schematic diagrams) will take on the value of either 1 (high) or 0 (low). Many flip-flops will also provide the complementary output (an inverted output).

Edge Triggering

Because the state of a flip-flop often depends on the previous state of a circuit (for example, the output of one flip flop may be the input to another), and because each flip-flop and logic gate needs a certain amount of time to switch its output, we usually clock the devices, that is, we synchonize all the flip-flops to change states at the same time with a clocked pulse. Flip-flops are edge triggered; they either change states when the clock goes from 0 to 1 (positive/rising edge) or when the clock goes from 1 to 0 (negative/falling edge).

Many flip-flops will also have a clear (CLR) and reset