Off line regulator

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An off line regulator, off-line regulator, or offline regulator is an electronic voltage regulation or current regulation device that is designed to directly accept electric power obtained from an alternating current utility power source. That is "off the mains voltage line".

This electronics design terminology has no relationship to the use of "online and offline" for computers and networking, and no relationship with uninterruptible power supplies that provide power while disconnected from the electrical grid.

An off line regulator can be a complete integrated circuit with all capabilities necessary to provide clean power to a small portable or handheld device,[1] or it may be used as part of a larger switched mode power supply (SMPS) or DC-DC converter.


Although alternating current is commonly described as being "120 V" or "240 V", this is the root mean square of the actual full peak voltage of the AC sinewave, which is +/- 170 V for 120 V and +/- 339 V for 240 V.

Additionally, 120 V and 240 V are considered nominal voltages, and actual voltages may be somewhat higher or lower during normal operation. The range of this variability is not well-defined but can be as much as +/- 20 volts (100 V - 140 V and 220 V - 260 V). This pushes the peak line voltage up to +/- 198 V for 120 V and +/- 368 V for 240 V.

Off line regulators must also be tolerant of voltage spikes, surges, brownouts, and other power quality conditions that may affect the electronic device.


  1. ^ "Offline Regulators - Switching Regulators".