Switching type AC adapter
First Claim
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1. A switching type AC adapter comprising:
- an output port for voltage output;
a current mode PWM controller connected to said output port through a resistance voltage shunt circuit to monitor variation of voltage output at said output port;
a synchronous circuit;
a monostable multivibrator connected to said current mode PWM controller and said synchronous circuit, and controlled to output a positive pulse and a negative pulse upon changing of logic level; and
a MOSFET having a gate connected to said current mode PWM controller, and a source connected to said monostable multivibrator through a buffer;
wherein said monostable multivibrator is charged to output a positive pulse and a negative pulse to drive said current mode PWM controller when the switching type AC adapter is electrically connected, and at the same time said synchronous circuit is controlled by a pulse output control time inputted from said monostable multivibrator to let said current mode PWM controller be controlled by pulse time from said monostable multivibrator, enabling switching time of said MOSFET be synchronized to synchronous signal from said synchronous circuit.
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Abstract
A switching type AC adapter includes a current mode PWM (pulse-width-modulated) controller, a monostable multivibrator, and a MOSFET so arranged that the current mode PWM controller and the monostable multivibrator are operated to let switching of the MOSFET be synchronized to synchronous signal from a synchronous circuit when the switching type AC adapter is electrically connected, enabling horizontal synchronizing interference to be concealed behind retrace time, and kept away from the screen of video equipment in which the switching type AC adapter is installed.
7 Citations
1 Claim
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1. A switching type AC adapter comprising:
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an output port for voltage output; a current mode PWM controller connected to said output port through a resistance voltage shunt circuit to monitor variation of voltage output at said output port; a synchronous circuit; a monostable multivibrator connected to said current mode PWM controller and said synchronous circuit, and controlled to output a positive pulse and a negative pulse upon changing of logic level; and a MOSFET having a gate connected to said current mode PWM controller, and a source connected to said monostable multivibrator through a buffer; wherein said monostable multivibrator is charged to output a positive pulse and a negative pulse to drive said current mode PWM controller when the switching type AC adapter is electrically connected, and at the same time said synchronous circuit is controlled by a pulse output control time inputted from said monostable multivibrator to let said current mode PWM controller be controlled by pulse time from said monostable multivibrator, enabling switching time of said MOSFET be synchronized to synchronous signal from said synchronous circuit.
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Specification
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Current AssigneeAllied Electronics Corporation Limited
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Original AssigneeProton Electronic Industrial Co., Ltd. (Kuo-Chai Construction)
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InventorsChen, Geoff
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Primary Examiner(s)STERRETT, JEFFREY L
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Application NumberUS09/232,658Time in Patent Office504 DaysField of Search363/21, 363/26, 363/41, 363/95, 363/97US Class Current363/41CPC Class CodesH02M 3/33507 with automatic control of t...
