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US 4,538,102 AGranted
Power supply circuit
AssigneeFujitsu Limited
InventorsMasayuki Takagi, Hiroshi Mugiya, Shigeru Komaju
Life of this patent
Estimating the term…
Abstract
A power supply circuit including a voltage stabilizing circuit and a voltage changing circuit responsive to an external control signal. The power supply circuit operates in one of two voltage-level changing modes. One mode changes the voltage level from a first stabilized output voltage to a second stabilized output voltage and the other mode cuts off or restores a stabilized output voltage.
Claims14
A power supply circuit receiving an external control signal, comprising:
- an output transistor having a base and outputting a stabilized voltage;
- a control transistor, operatively connected to the base of said output transistor, having a base and controlling the base potential of said output transistor;
- impedance means, operatively connected to the base of said control transistor, for dividing the stabilized voltage and applying a divided voltage to the base of said control transistor;
- and
- switching means operatively connected to said impedance means and to receive the external control signal, for varying the division ratio of said impedance means.
2 more elements
A power supply circuit receiving an input voltage, comprising:
- control signal means, operatively connected to receive the input voltage, for supplying first and second control signals;
- a stabilized voltage outputting circuit outputting a stabilized voltage, comprising an output transistor, operatively connected to receive the input voltage and having a base, said stabilized voltage outputting cirucit stabilizing the input voltage;
- thyristor means, operatively connected to said control signal means and the base of said output transistor, for conducting when the first control signal exceeds a first predetermined value;
- and
- switching means, operatively connected to said control signal means and in series with said thyristor means, for switching on when the second control signal exceeds a second predetermined value lower than the first predetermined value, and causing the stabilized voltage to drop from a prior level when the first control signal exceeds the first predetermined value and return to the prior level when the second control signal drops below the second predetermined value.
2 more elements
Dependencies are inferred from the claim text.