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Short Circuit Protection and Starting Device for Series Regulator

IP.com Disclosure Number: IPCOM000094766D
Original Publication Date: 1965-May-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Leung, WC: AUTHOR

Abstract

The voltage regulator has a series transistor 2 connected between a pair of unregulated terminals 3 and 4 and a pair of regulated terminals 5 and 6. A network of resistors and a reference diode provide signal V1 indicating the regulator voltage and signal V2 indicating a reference voltage. A differential amplifier is connected to receive two signals and to vary the base current to transistor 2 to maintain the selected regulated voltage.

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Short Circuit Protection and Starting Device for Series Regulator

The voltage regulator has a series transistor 2 connected between a pair of unregulated terminals 3 and 4 and a pair of regulated terminals 5 and 6. A network of resistors and a reference diode provide signal V1 indicating the regulator voltage and signal V2 indicating a reference voltage. A differential amplifier is connected to receive two signals and to vary the base current to transistor 2 to maintain the selected regulated voltage.

Because the base current for the transistor of the differential amplifier is supplied from the regulated terminals, it is necessary to provide current to transistor 2 during start-up when the voltage at the regulated terminals is zero. Circuits of this type are usually arranged to receive control current from the unregulated terminals temporarily during start-up. Start-up circuits of this general type can also be arranged to provide short-circuit protection for transistor 2. When a short circuit occurs across the regulated terminals, such a start-up circuit provides sufficient base drive to transistor 2 to keep it in saturation so that power dissipation of the transistor 2 is kept low in spite of its abnormally large current. Resistor 7 limits the current to a value within the rating of transistor 2 and a fuse interrupts the current to protect the load.

This regulator has an improved circuit for start-up and for short-circuit protection. The protection and start-up...