______________________________________________________________ Solid State Power Supplies
VOLTAGE REGULATORS - circuits designed to maintain the output of power
supplies at a constant amplitude despite variations of the AC source voltage or
changes of the resistance of the load. This is done by creating a voltage divider
of a resistive element in the regulator and the resistance of the load. Regulation
is achieved by varying the resistance of the resistive element in the regulator.
Regulation is achieved by varying this resistance either to increase or to
decrease the voltage drop across the resistive element of the regulator.
Characteristically, the resistance of the variable resistance moves in the same
direction as the load. When the resistance of the load increases, the variable
resistance of the regulator increases; when load resistance decreases, the
variable resistance of the regulator decreases.
load. Regulation is achieved by keeping the resistance of the load constant.
Characteristically, the resistance of the shunt moves in the opposite direction
of the resistance of the load.
CURRENT LIMITER - a short-circuit protection device that automatically limits
the current to a safe value. This is done when the current-limiting transistor
senses an increase in load current. At this time the current-limiting transistor
decreases the voltage on the base of the pass transistor in the regulator, causing
a decrease in its conduction. Therefore, current cannot rise above a safe value.
23 June 2005
TC 9-62
4-51
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