REGULATED DC POWER UNIT AND OPTICAL MEDIUM EQUIPMENT USING THE SAME

Japanese Patent JP3464413

B2

PROBLEM TO BE SOLVED: To further improve the efficiency of a regulated DC power unit provided with a switching regulator power source circuit on the preceding stage side and a dropper-type regulated power unit circuit on the poststage side, and at the same time, to suppress quantity of heat generated from the power unit by utilizing the improved efficiency.
SOLUTION: The base current of an output transistor Q1 of a dropper type regulator power source circuit is detected by means of a detecting resistor R3 and an error amplifier A2, a reference voltage source B2, a comparator A3, and an oscillation circuit E in a switching regulator power source circuit 12 change the output voltage of a regulator DC power unit, by controlling the duty of a switching element SW1 so that the detected value of the base current becomes a fixed value, at which the transistor Q1 become saturated correspondingly to the resistance of a load 17. Consequently, the transistor Q1 becomes a large DC amplification factor, when the output current of the power unit is large and become a small DC amplification factor, when the output current is small. Therefore, heat generation in the power unit can be minimized with maximum efficiency, by suppressing the difference between the input voltage and output voltage to the minimum value corresponding to the output current.

Takashi Shirai

JP15984499A

November 10, 2003

June 07, 1999

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Sharp Corporation

G05F3/16; G05F1/56; H02M3/155; (IPC1-7): H02M3/155; G05F1/56; G05F3/16

JP795765A
JP421111A
JP1097328A

Kenzo Hara

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