Patent Publication Number: US-2012026634-A1

Title: Voltage detection circuit device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the invention 
     The present invention relates to a voltage detection circuit device, more particularly to a circuit device that compares a voltage of a power source of a power supply circuit and determines whether or not the voltage falls within a normal range, so as to prevent an electronic circuit from being damaged by an abnormal power supply. 
     2. Description of Related Art 
     In general, when a power supply starts outputting an operating voltage, the electric potential of the operating voltage not necessarily reaches a normal electric potential at the beginning, and the operating voltage must go through a delay time before it reaches the normal electric potential. During the period for the operating voltage to rise to the critical electric potential, the power supply can enable an electric potential confirm signal to inform an external system to be turned on. 
     If the operating voltage rises and reaches the critical potential, the electric potential confirm signal will start pulling, such that the electric potential confirm signal will be enabled to a high potential after it has gone through the rising time. Ideally, the electric potential confirm signal has a smooth rising edge in the rising time. However, the rising time is usually very long, so that a jitter of the rising edge of the electric potential confirm signal may occur easily due to noises, and a misjudgment may be made by an external system easily. 
     Obviously, the foregoing prior art has drawbacks and requires improvements. 
     SUMMARY OF THE INVENTION 
     In view of the aforementioned shortcomings of the conventional power supply, the inventor of the present invention based on years of experience in the related industry to conduct extensive researches and experiments, and finally developed a voltage detection circuit device in accordance with the present invention to overcome the shortcomings of the prior art. 
     Therefore, it is a primary objective of the present invention to provide a voltage detection circuit device capable of detecting an electric potential of a power supply circuit automatically, such that an electric power is supplied when the electric potential reaches a normal range. 
     To achieve the foregoing objective, the present invention provides a voltage detection circuit device comprising a power supply circuit, and the power supply circuit comprises a voltage acquisition circuit, a voltage step-down circuit and a compare circuit, wherein the voltage acquisition circuit is comprised of a plurality of resistors with different resistance and a plurality of fuses connected in parallel with each other, and a portion of blown fuses can step down a power source of the power supply circuit via a predetermined number of resistors to acquire a predetermined compare voltage; the voltage step-down circuit is electrically coupled to the voltage acquisition circuit and composed by connecting two resistors to a fuse in parallel to each other, such that the fuse can be blown/not blown to step down the compare voltage by one of the resistors; the compare circuit is electrically coupled to the voltage step-down circuit and includes a high potential comparator and a low potential comparator, wherein the high potential comparator can compare the compare voltage with the voltage of a power source of the power supply circuit, such that if the voltage of the power source of the power supply circuit falls within a normal range, then a high potential signal will be outputted. The low potential comparator can compare the compare voltage with the voltage of a power source of the power supply circuit, such that if the voltage of the power source of the power supply circuit falls within the normal range, then a low potential signal will be outputted. When use, the power source of the power supply circuit acquires the predetermined compare voltage by the voltage acquisition circuit. After the voltage is stepped down by the voltage step-down circuit, the compare voltage will act as a voltage reference, and a high potential comparator and a low potential comparator of the compare circuit compare the voltage of the power supply of the power supply circuit. If the voltage of the power supply of the power supply circuit falls within a normal range, the high potential comparator will output a high potential signal, while the low potential comparator will output a low potential signal, such that after an electronic circuit supplied with electric power receives the electric potential signals, the electronic circuit will start its operation by using the power source of the power supply circuit. By comparing and determining whether or not the power source of the power supply circuit falls within the normal range, damages to the electronic circuit by abnormal power supply can be prevented. 
     The technical contents and effects of the present invention will become apparent with the detailed description of a preferred embodiment of the present invention together the illustration of a related drawing as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic circuit diagram of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 1  for a voltage detection circuit device of the present invention, the voltage detection circuit device comprises a power supply circuit  1  including a voltage acquisition circuit  11 , a voltage step-down circuit  12  and a compare circuit  13 . 
     The voltage acquisition circuit  11  comprises a plurality of resistors with different resistance  111  and a plurality of fuses  112  connected in parallel, and a portion of blown fuses  112  can step down the voltage of a power source  10  of the power supply circuit  1  through a predetermined number of resistors  111  to acquire a predetermined compare voltage. 
     The voltage step-down circuit  12  is electrically coupled to the voltage acquisition circuit  11 , and formed by connecting two resistors  121  and a fuse  122  in parallel, such that the fuse  122  can be blown/not blown to step down the compare voltage by one of the resistors  121 . 
     The compare circuit  13  is electrically coupled to the voltage step-down circuit  12  and includes a high potential comparator  131  and a low potential comparator  132 , wherein the high potential comparator  131  can compare the compare voltage with the voltage of the power source  10  of the power supply circuit  1 . If the power source  10  of the power supply circuit  1  falls within a normal range, a high potential signal will be outputted; and the low potential comparator  132  can compare the compare voltage with the voltage of the power source  10  of the power supply circuit  1 . If the power source  10  of the power supply circuit  1  falls within the normal range, a low potential signal will be outputted. 
     With the assembly of the foregoing components, the power supply  10  of the power supply circuit  1  acquires the predetermined compare voltage through the voltage acquisition circuit  11 . After the voltage step-down circuit  12  steps down the voltage, the compare voltage will act as a voltage reference, and the high potential comparator  131  and the low potential comparator  132  of the compare circuit  13  compare the power source  10  of the power supply circuit  1 , such that if the voltage of the power source  10  of the power supply circuit  1  falls within the normal range, the high potential comparator  131  will output a high potential signal, while the low potential comparator  132  will output a low potential signal, such that after an electronic circuit (not shown in the figure) supplied with an electric power receives the electric potentials, the electronic circuit starts its operation by using the power source  10  of the power supply circuit  1 . By comparing and determining whether or not the voltage of the power source  10  of the power supply circuit  1  falls within the normal range, damages to an electronic circuit supplied with an abnormal power supply can be prevented. 
     Many changes and modifications in the above described embodiment of the invention can, of course, be carried out without departing from the scope thereof. Accordingly, to promote the progress in science and the useful arts, the invention is disclosed and is intended to be limited only by the scope of the appended claims.