Patent ID: 6538417
Filing Date: 2003-03-25
Classification: G05F

Abstract:
A voltage regulating device comprising:a first input terminal for receiving a fixed reference voltage; a second input terminal for receiving a voltage proportional to an output voltage of the device; first comparison means having a first input terminal and a second input terminal and for comparing the voltage proportional to the output voltage with the fixed reference voltage; variable resistance-forming means controlled by an output of said first comparison means and for tapping off the voltage proportional to the output voltage so that the output voltage remains substantially constant; second comparison means connected to said first input terminal and for comparing a voltage proportional to a variable input voltage of the device and the fixed reference voltage; and switching means controlled by an output of said second comparison means and for sending the fixed reference voltage to the first input terminal of said first comparison means when the fixed reference voltage is less than the voltage proportional to the variable input voltage, and for sending the voltage proportional to the variable input voltage to said first input terminal of said first comparison means when the fixed reference voltage is greater than the voltage proportional to the variable input voltage so that the output voltage remains substantially constant when the variable input voltage is greater than a threshold voltage, and the output voltage remains substantially equal to the variable input voltage when the variable input voltage is less than the threshold voltage.