Current control circuit
AssigneeFujitsu Limited
InventorKouichi Matsuo
Life of this patent
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Abstract
There is disclosed a current control circuit, disposed between a primary terminal and a secondary terminal, for controlling a current flowing from the primary terminal to the secondary terminal. An overcurrent flowing through a resistance R1 is detected by a PNP transistor. A maximum value of a current flowing through a MOSFET is determined by a voltage dropped by a voltage drop correspondence by a diode from a voltage of the collector of the PNP transistor.
Claims7
A current control circuit, disposed between a primary terminal and a secondary terminal, for controlling a current flowing from the primary terminal to the secondary terminal, said current control circuit comprising:
- a first resistance disposed on a current path directed from the primary terminal to the secondary terminal;
- a MOSFET, in which its drain and source are connected in series to said first resistance, disposed between said first resistance and the secondary terminal, said MOSFET permitting a maximum permissible current or less current to conduct in accordance with a voltage applied to its gate;
- a PNP transistor in which its emitter is connected to a primary of said first resistance and its base is connected to the secondary of said first resistance;
- and
- a voltage drop device, disposed between the collector of said PNP transistor and the gate of said MOSFET, for supplying to the gate of said MOSFET a voltage dropped by a predetermined potential from a voltage of the collector of said PNP transistor.
Dependencies are inferred from the claim text.