Clock rate

The switching frequency (with the SI unit: Hz) indicates the number of times an electronic component or circuit is switched on and off per time interval.

$f_{\mathrm {Schalt} }={\frac {1}{T_{\mathrm {aus} }+T_{\mathrm {anstieg} }+T_{\mathrm {ein} }+T_{\mathrm {abfall} }}}$

Where $T_{\mathrm {aus} }$ the off-state time, $T_{\mathrm {anstieg} }$ rise time, $T_{\mathrm {ein} }$ on-state time and $T_{\mathrm {abfall} }$ the fall time. Rise and fall times are normally considerably smaller than the on-state times and can be neglected if necessary, so that the equation becomes

$f_{\mathrm {Schalt} }={\frac {1}{T_{\mathrm {aus} }+T_{\mathrm {ein} }}}$

can be simplified.

The greater the switching frequency, the more frequently the switching process can be carried out in a period of time, or the faster the switching process.

With switching power supplies, the switching frequency is often in the range of 10 kHz to 20 kHz, which is largely within the audible range of human hearing and can be perceived as a monotonous whistling noise.

High switching frequencies of transistors enable, for example, the clock frequencies of modern processors and satellite communication in the GHz range.

The switching frequency is not to be confused with the specification of the maximum switching cycles. This indicates the average number of switching operations that can be carried out until the wear of the switching contacts has progressed to such an extent that reliable connection or disconnection can no longer be guaranteed. This specification occurs exclusively with mechanical contacts such as relays and reed contacts. For semiconductors, the number of switching cycles is unlimited.

Clock rate

See also

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