CROWBAR CIRCUIT

An overvoltage protection circuit that monitors the output voltage of the supply and rapidly places a short circuit (or crowbar) across the output terminals if a preset voltage level is exceeded.

CURRENT FOLDBACK

Another form of current limiting often used in fixed output voltage supplies. For load resistance smaller than the crossover value, the current, as well as the voltage, decreases along a foldback locus.

DRIFT

The maximum change in power supply output during a stated period of time (usually 8 hours) following a warm-up period, with all influence and control quantities (such as; load, ac line, and ambient temperature) maintained constant. Drift includes periodic and random deviations (PARD) over a bandwidth from dc to 20Hz. (At frequencies above 20Hz, PARD is specified separately.)

EFFICIENCY

Expressed in percent, efficiency is the total output power of the supply divided by the active input power. Unless otherwise specified, Agilent measures efficiency at maximum rated output power and at worst case conditions of the ac line voltage.

ELECTROMAGNETIC INTERFERENCE (EMI)

Any type of electromagnetic energy that could degrade the performance of electrical or electronic equipment. The EMI generated by a power supply can be propagated either by conduction (via the input and output leads) or by radiation from the units' case. The terms "noise" and "radio-frequency interference" (RFI) are sometimes used in the same context.

INRUSH CURRENT

The maximum instantaneous value of the input current to a power supply when ac power is first applied.

11

Page 10
Image 10
Agilent Technologies 90B manual Crowbar Circuit, Current Foldback, Drift, Efficiency, Electromagnetic Interference EMI