Adapter circuit for selectively doubling input voltage...

Details Adapter circuit for selectively doubling input voltage... Adapter circuit for selectively doubling input voltage...

2001-04-02

2002-10-01

Riley, Shawn (Department: 2838)

Electric power conversion systems

Current conversion

With means to connect the input to diverse power sources

C363S016000

Reexamination Certificate

active

06459603

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to power supplies, and more particularly to AC/DC adapter circuits in power supplies.
BACKGROUND OF THE INVENTION
The voltage of the alternating current (AC) sources from typical outlets vary from country to country, mostly between 90V and 265V. The alternating current/direct current (AC/DC) adapters for laptop computer power supplies and for batteries of most mobile products need to be compatible for these various AC sources.
FIG. 1
is a circuit diagram illustrating a conventional AC/DC adapter. This circuit
100
is compatible with AC sources ranging from 90V to 265V. The circuit
100
comprises a rectifier bridge
104
which fully rectifies the AC voltage input from the AC source
102
. The AC voltage from the rectifier bridge
104
charges the input capacitor C
1
106
, developing a DC voltage. Thus, the DDC voltage across C
1
106
can vary from a low 100V DC to a high 375V DC. The transformer T
9
108
is a flyback transformer that stores the energy when transistor Q
2
110
is “on ”, and releases the energy to the output when Q
2
110
is “off”. The DC output voltage is filtered by diode D
8
112
and capacitor C
5
114
. The DC output voltage is regulated by an error amplifier
116
, which changes the pulse width of the switcher using the pulse width modulator
118
(PWM).
However, because T
9
108
is a storage transformer, its size is large. Since Q
2
110
is a high current, high voltage transistor required for wide range of input voltage, its size is large. In addition, due to the very wide range of AC input voltage, the circuit
100
cannot operate at a very high frequency, i.e., greater than 150 KHz. For these reasons, the size of the circuit
100
is very large. Due to its large size and its requirement to accommodate a wide range of AC input voltages, the circuit
100
is inefficient.
Accordingly, there exists a need for an adapter circuit which improves efficiency and size. The present invention addresses such a need.
SUMMARY OF THE INVENTION
The present invention provides an adapter circuit which improves efficiency and size. The adapter circuit includes: a selective voltage doubler which approximately doubles an input voltage with a low line connector and does not with a high line connector; a switcher coupled to the selective voltage doubler; a resonant circuit coupled to the switcher; a first diode and a second diode coupled to the resonant circuit; and a filter coupled to the first and second diodes. When a low line connector is used, the input voltage is doubled and a one diode drop is used. When a high line connector is used, the input voltage is not doubled and a two diode drop is used. This allows the adapter circuit to be significantly reduced in size and weight. It also has low power loss.


REFERENCES:
patent: 3723850 (1973-03-01), Daniels et al.
patent: 4626981 (1986-12-01), Su et al.
patent: 4903181 (1990-02-01), Seidel
patent: 4937731 (1990-06-01), Konopka
patent: 5118301 (1992-06-01), Bentivolio
patent: 5119283 (1992-06-01), Steigerwald et al.
patent: 5661348 (1997-08-01), Brown
IBM Technical Disclosure Bulletin; vol. 31, No. 6, Nov. 1988; Constant Power Fusing Arrangement for 110/220-Volt Power Supplies pp. 57-58.
IBM Technical Disclosure Bulletin; vol. 32, No. 6B, Nov. 1989; Power Supply Universal Front End pp. 155-156.

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