Tastverhältnis

Tastverhältnis, commonly translated as duty cycle in English, is a term used in electronics to describe the proportion of time a periodic signal remains in the ON state within one cycle. It is defined as the ratio ton/T, where ton is the duration of the high level inside a cycle of length T. Expressed as a percentage, D% = (ton/T) × 100.

In pulse-width modulation (PWM) and switching power supplies, the Tastverhältnis determines the average voltage delivered to a load: a higher duty cycle increases the average voltage and power, while a lower duty cycle reduces them. The switching frequency (the reciprocal of T) is a separate parameter; changing the duty cycle alters the average output without necessarily changing the frequency.

Measurement and interpretation: The duty cycle can be measured with an oscilloscope by observing a periodic waveform and calculating the ratio of the high time to the total period. Many digital multimeters and power supplies also display duty cycle values.

Applications: Tastverhältnis is central to DC motor control, LED dimming, and voltage regulators. In fast-switching systems, extreme duty cycles (near 0% or 100%) can influence efficiency, switching losses, and the need for output filtering.

Relation to related concepts: It is distinct from the switching frequency, peak voltage, and waveform amplitude. PWM uses variations in duty cycle to modulate the average output while keeping switching events within a defined frequency.

Usage note: In German-language literature and technical documentation, Tastverhältnis is a standard term for duty cycle and is encountered across electronics, communications, and control engineering since the mid-20th century.