What is "duty cycle"

n. (context electronics English) The ratio between the amount of time in which the clock's signal is high and the clock's period.

A duty cycle is the percentage of one period in which a signal or system is active. A period is the time it takes for a signal to complete an on-and-off cycle. As a formula, a duty cycle may be expressed as:

$$D = \frac{T}{P} \times 100\%$$

where D is the duty cycle, T is the time the signal is active, and P is the total period of the signal. Thus, a 60% duty cycle means the signal is on 60% of the time but off 40% of the time. The "on time" for a 60% duty cycle could be a fraction of a second, a day, or even a week, depending on the length of the period.

Duty cycles can be used to describe the percent time of an active signal in an electrical device such as the power switch in a switching power supply or the firing of action potentials by a living system such as a neuron.

The duty factor for periodic signal expresses the same notion, but is usually scaled to a maximum of one rather than 100%.