Patent Publication Number: US-2013229161-A1

Title: Modulating determination apparatus, modulating determination method, and power supply circuit thereof

Description:
This application claims priority to Taiwan Patent Application No. 101106728 filed on Mar. 1, 2012. 
     CROSS-REFERENCES TO RELATED APPLICATIONS 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a modulating determination apparatus, a modulating determination method for use in a power supply circuit, and the power supply circuit. More particularly, the present invention relates to a power supply circuit having a plurality of modulating schemes, a modulating determination apparatus thereof, and a modulating determination method thereof. 
     2. Descriptions of the Related Art 
     Stable supply of electric power is an important factor for ensuring normal operations of various electronic circuits. In general electronic circuits, a regulator is disposed to supply a stable and reliable voltage level. However, different electronic circuits require different power supplies. In order to satisfy demands of different voltages in various electronic circuits, power supply integrated circuit (IC) manufacturers must design different kinds of regulators. For example, switching regulators and linear regulators are common ones, and among linear regulators, low dropout linear regulators have the simplest structures and are widely used. 
     Different regulators have to be coupled with different circuit components when being used. As an example, a switching regulator has to be coupled with an additional passive component (e.g., an inductor) when being used. In case no passive component is coupled in the circuit of the switching regulator or in case the passive component is broken due to factors such as dusts and moisture, the circuit becomes short-circuited. For this situation, a square-wave signal modulated by a switching circuit is presented directly at the output end, which cannot be used in the back-end circuits and may even damage components of the back-end circuits. As another example, when a low dropout linear regulator is used, no additional passive component is needed and, instead, it is connected in a short-circuited fashion for ensuring the voltage quality. If a passive component is coupled to the low dropout liner regulator, the low dropout linear regulator cannot operate efficiently. 
     Accordingly, there is an urgent need in the art to provide a technology that can detect a passive component conveniently to ensure normal operation of various electronic circuits (e.g., regulators). 
     SUMMARY OF THE INVENTION 
     The present invention provides a modulating determination apparatus and a modulating determination method for use in a power supply circuit, and the power supply circuit. 
     The modulating determination apparatus is for use in a power supply circuit, is configured to be coupled to an examined circuit, and comprises a driver circuit and a comparison circuit. The examined circuit has a first end and a second end. The driver circuit provides an impulse signal to the first end. The comparison circuit is coupled to the first end to obtain a first detected electric value of the first end, calculates a difference value between the first detected electric value and a second detected electric value, and produces a comparison result by comparing the difference value with a threshold value. The comparison result indicates whether the examined circuit comprises a passive component, which is used to decide to modulate the power supply circuit by either a first modulating scheme or a second modulating scheme so as to supply an output power. 
     The modulating determination method is for use in a power supply circuit and comprises the following steps of: (a) providing an impulse signal to an end of an examined circuit; (b) detecting the end to obtain a first detected electric value; (c) obtaining a second detected electric value; (d) calculating a difference value between the first detected electric value and the second detected electric value; (e) producing a comparison result by comparing the difference value with a threshold value, the comparison result indicating whether the examined circuit comprises a passive component; and (f) modulating the power supply circuit by either a first modulating scheme or a second modulating scheme according to the comparison result so as to supply an output power. 
     The power supply circuit comprises a pin, a driver circuit, a comparison circuit, a switching regulator, a low dropout linear regulator, and a selection circuit. The pin is to be coupled to an examined circuit. The driver circuit is coupled to the pin and for providing an impulse signal to the examined circuit. The comparison circuit is coupled to the first pin to obtain a first detected electric value and for producing a comparison result according to a difference value between the first detected electric value and a second detected electric value. The selection circuit decides to supply an output power by either the switching regulator or the low dropout linear regulator according to the comparison result. 
     The present invention determines whether an examined circuit comprises a passive component by obtaining two detected electric values of two ends of the examined circuit and then comparing a difference value between the two detected electric values with a threshold value. Therefore, the present invention can efficiently detect whether an examined circuit comprises a desired passive component. When this technology is applied to a power supply circuit, the power supply circuit can determine whether a passive component is coupled by a user so as to activate a proper circuit or output a proper signal. 
     The detailed technology and preferred embodiments implemented for the subject invention are described in the following paragraphs accompanying the appended drawings for people skilled in this field to well appreciate the features of the claimed invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates the modulating determination apparatus of the first embodiment; 
         FIG. 2  illustrates the modulating determination apparatus of the second embodiment; 
         FIG. 3  illustrates the modulating determination method of the third embodiment; 
         FIG. 4  illustrates the power supply circuit of the fourth embodiment; 
         FIG. 5  illustrates the power supply circuit of the fifth embodiment; 
         FIG. 6  illustrates the power supply circuit of the sixth embodiment; 
         FIG. 7  illustrates the power supply circuit of the seventh embodiment; 
         FIG. 8  illustrates the power supply circuit of the eighth embodiment; and 
         FIG. 9  illustrates the power supply circuit of the ninth embodiment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the following description, the principle of the present invention will be described in detail. In addition, the modulating determination apparatus and the modulating determination method for use in a power supply circuit as well as the power supply circuit based on the present invention will be explained with reference to various embodiments. However, these embodiments are not intended to limit the present invention to any environment, applications, or implementations described in these embodiments. Therefore, description of these embodiments is only for purpose of illustration rather than to limit the present invention. It shall be appreciated that, in the following embodiments and the attached drawings, elements not directly related to the present invention are omitted from depiction. 
     The impedance of a passive component is related with the frequency of an input signal. For example, the impedance of an inductor is directly proportional to the frequency of an impulse signal inputted. Hence, the higher the frequency of the impulse signal is, the larger the potential difference across the inductor will be. Such a characteristic of the inductor may also be reflected by other detected electric values, e.g. current values. 
       FIG. 1  depicts the first embodiment of the present invention. The modulating determination apparatus  1  comprises the driver circuit  11  and the comparison circuit  13 , while the examined circuit  15  has the first end  151  and the second end  153 . In this embodiment, the modulating determination apparatus  1  may be a power supply control integrated circuit (IC) and the examined circuit  15  may be any external circuit that needs to be connected with the power supply control IC to jointly output an appropriate power to back-end circuits. As shown in  FIG. 1 , the first end  151  of the examined circuit  15  is coupled to the driver circuit  11  and the comparison circuit  13 , while the second end  153  is an output end which may be grounded or coupled to other electronic circuit components having a fixed detected electric value. 
     The driver circuit  11  provides the impulse signal  100  to the first end  151  of the examined circuit  15 . Then, the comparison circuit  13  detects the first end  151  to obtain a first detected electric value and calculates a difference value between the first detected electric value and a second detected electric value of the second end  153 . Since the output of the second end  153  is an expectable known value, the second detected electric value may be built in as a default value. Therefore, after detecting the first end  151 , the comparison circuit  13  directly calculates the difference value between the first detected electric value and the built-in second detected electric value and then compares the difference value with a threshold value to output the comparison result  115 . The comparison result  115  indicates whether the examined circuit  15  comprises a passive component. When the modulating determination apparatus  1  is used in a power supply circuit, modulating the power supply circuit by either a first modulating scheme or a second modulating scheme is decided according to whether a passive component exists so as to supply an output power. 
     In other embodiments, depending on the type and characteristics of the passive component and the type of the detected electric values, the comparison result  115  will present whether the examined circuit  15  comprises a passive component in different ways. For example, in case that the impedance of the passive component to be detected is positively correlated with the frequency of the impulse signal  100 , the examined circuit  15  is determined to comprise the passive component if the comparison circuit learns that the difference value between the first detected electric value and the second detected electric value is greater than the threshold value. Continuing the same example, it is determined that the examined circuit  15  does to not comprise the passive component if the difference value between the first detected electric value and the second detected electric value is smaller than the threshold value. 
     The first detected electric value and the second detected electric value may be voltage values or current values. The passive component may be an inductor or a capacitor. In different embodiments, the present invention may be implemented by choosing different detected electric values according to the characteristics of the passive component to be measured. 
       FIG. 2  depicts the second embodiment of the present invention. The modulating determination apparatus  2  comprises the driver circuit  21  and the comparison circuit  23 , while the examined circuit  25  has the first end  251  and the second end  253 . As the modulating determination apparatus  2  is similar to the modulating determination apparatus  1  of the first embodiment, only the differences therebetween are described below. 
     In the second embodiment, the comparison circuit  23  is coupled to not only the first end  251  but also the second end  253  of the examined circuit  25 . Therefore, when the driver circuit  21  provides an impulse signal  200  to the first end  251 , the comparison circuit  23  can directly detect and obtain a first detected electric value of the first end  251  and a second detected electric value of the second end  253 . The difference value between the first detected electric value and the second detected electric value is compared with a threshold value by the comparison circuit  23  to output the comparison result  215 . The comparison result  215  indicates whether the examined circuit  25  comprises a passive component. 
     In actual circuits, the output level of the second end  253  of the examined circuit  25  is expectable. Considering the example that the modulating determination apparatus  2  is a power supply control IC and the examined circuit  25  is an output inductor and they form a switching regulator (SWR) together. In this case, regardless of whether the second end  253  is coupled to the comparison circuit  23 , the difference value between the first detected electric value and the second detected electric value can be predicted through some techniques so as to determine the threshold value. In practical implementations, the input end for inputting the second detected electric value of the comparison circuit  23  may be designed to be grounded or directly coupled to some other node having a fixed voltage. In a preferred embodiment, the second detected electric value is a nonzero default value. As long as the difference value between the first detected electric value and the second detected electric value can exhibit the electric characteristic of the examined circuit  25  adequately and the threshold value is appropriately set, whether the examined circuit  25  comprises a passive component can be effectively determined It shall be noted that, if the comparison result  215  indicates that the examined circuit  25  has no inductive characteristic, it represents that the current circuit cannot be provided with a power by an SWR control approach. In this case, the output of the power supply must be turned off; or instead, the power is outputted by some other control approach that does not require existence of an inductor (e.g., the output is supplied to the second end  253  by a control approach using a low dropout linear regulator instead). 
     The third embodiment of the present invention is a modulating determination method, a flowchart diagram of which is depicted in  FIG. 3 . This modulating determination method can be applied to a power supply circuit. Hardware architectures that can realize this modulating determination method can refer to the modulating determination apparatus  1  or the modulating determination apparatus  2  described above. 
     Firstly, step S 301  is executed to provide an impulse signal to an end of an examined circuit. Next, step S 303  is executed to detect the end of the examined circuit to obtain a first detected electric value. Then, step S 305  is executed to obtain a second detected electric value. It shall be appreciated that, in other embodiments, step S 305  may be executed before step S 303  or steps S 303  and S 305  may be executed simultaneously. 
     Then, step S 307  is executed to calculate a difference value between the first detected electric value and the second detected electric value. Step S 309  is executed to compare the difference value with a threshold value to produce a comparison result, which indicates whether the examined circuit comprises a passive component. Finally, step S 311  is executed to modulate the power supply circuit by either a first modulating scheme or a second modulating scheme according to the comparison result so as to supply an output power. 
       FIG. 4  depicts the fourth embodiment of the present invention. The power supply circuit  4  comprises the pin  451 , the driver circuit  41 , the comparison circuit  43 , the switching regulator  47 , the low dropout linear regulator  49 , and the selection circuit  44 . The selection circuit  44  comprises the D-type flip-flop  433  and the multiplexer  444 . 
     In this embodiment, the driver circuit  41  may be a p-channel metal-oxide-semiconductor field-effect transistor (PMOSFET). Additionally, the driver circuit  41 , the comparison circuit  43 , the switching regulator  47 , the low dropout linear regulator  49 , the D-type flip-flop  433 , and the multiplexer  444  are all well known by those of ordinary skill in the art, and thus will not be further described herein. 
     As shown, when the end  402  of the examined circuit  45  is coupled to the pin  451 , the driver circuit  41  provides the impulse signal  400  to the examined circuit  45  via the pin  451 . The comparison circuit  43  also detects and obtains a first detected electric value of the end  402  via the pin  451 , calculates a difference value between the first detected electric value and the second detected electric value Ref, and produces the comparison result  432  according to the difference value (e.g., by comparing the difference value with a threshold value). 
     The selection circuit  44  decides to supply an output power by either the switching regulator  47  or the low dropout linear regulator  49  according to the comparison result  432 . 
     Specifically, the D-type flip-flop  433  is coupled to the comparison circuit  43 , receives the comparison result  432  from the comparison circuit  43 , and outputs the control signal  430  according to the comparison result  432 . The multiplexer  444  is coupled to the switching regulator  47 , the low dropout linear regulator  49 , and the D-type flip-flop  433 . According to the control signal  430 , the first output signal  471  generated by the switching regulator  47  or the second output signal  491  generated by the low dropout linear regulator  49  is outputted by the multiplexer  444  to the pin  451  as the output power for output to the examined circuit  45 . 
     When the power supply circuit  4  starts to provide the output power to the examined circuit  45 , the driver circuit  41  stops providing the impulse signal  400  to the examined circuit  45 . In other embodiments, the driver circuit  41  may be activated when connection of the examined circuit is detected (hot plugging detection) and then turned off after a preset time period, or may execute other commands from the system. 
       FIG. 5  depicts the fifth embodiment of the present invention. The power supply circuit  5  of this embodiment is similar to the power supply circuit  4  of the fourth embodiment, so only the differences therebetween are focused below. In this embodiment, the end  402  and the end  504  of the examined circuit  45  are coupled to the pin  451  and the pin  553  of the power supply circuit  5  respectively. Therefore, the comparison circuit  53  not only obtains the first detected electric value via the pin  451  but also obtains the second detected electric value via the pin  553 . Then, the comparison circuit  53  calculates the difference value between the first detected electric value and the second detected electric value and outputs the comparison result  432  by comparing the difference value with a threshold value. Afterwards, since the comparison result  432  indicates whether a passive component exists or not, the D-type flip-flop  433  and the multiplexer  444  choose to operate in different ways accordingly so that the first output signal  471  generated by the switching regulator  47  or the second output signal  491  generated by the low dropout linear regulator  49  is outputted to the pin  451  as the output power for output to the examined circuit  45 . 
       FIG. 6  depicts the sixth embodiment of the present invention. The power supply circuit  6  comprises the pin  651 , the driver circuit  61 , the comparison circuit  63 , the switching regulator  67 , the low dropout linear regulator  69 , and the selection circuit  66 . The selection circuit  66  comprises the D-type flip-flop  62 , the inverter  60 , and the enabling circuit  64 . 
     The end  602  of the examined circuit  65  is coupled to the power supply circuit  6  via the pin  651 . In this embodiment, the driver circuit  61  may be a PMOSFET. The driver circuit  61  provides the impulse signal  600  to the pin  651 . The comparison circuit  63  is coupled to the pin  651 , obtains a first detected electric value from the pin  651 , calculates a difference value between the first detected electric value and a preset second detected electric value Ref, and produces the comparison result  632  according to the difference value. 
     The selection circuit  66  decides to supply an output power by either the switching regulator  67  or the low dropout linear regulator  69  according to the comparison result  632 . Specifically, the D-type flip-flop  62  is coupled to the comparison circuit  63  and outputs a control signal  633  according to the comparison result  632 . The input end of the inverter  60  is coupled to the D-type flip-flop  62  and the inverter  60  generates an inverted signal EN-SWR according to the control signal  633 . The enabling circuit  64  is coupled to the switching regulator  67 , the low dropout linear regulator  69 , and the inverter  60 , receives the inverted signal EN-SWR from the inverter  60 , and enables either the switching regulator  67  or the low dropout linear regulator  69  according to the inverted signal EN-SWR. The switching regulator  67  or the low dropout linear regulator  69  that is enabled then supplies the output power to the examined circuit  65  via the pin  651 . 
       FIG. 7  depicts the seventh embodiment of the present invention. The end  602  and the end  704  of the examined circuit  65  are coupled to the pin  651  and the pin  753  of the power supply circuit  7  respectively. The comparison circuit  73  receives a first detected electric value via the first pin  651  and also receives a second detected electric value via the second pin  753 . The comparison circuit  73  then calculates the difference value between the first detected electric value and the second detected electric value and outputs the comparison result  632  by comparing the difference value with a threshold value. 
       FIG. 8  depicts the eighth embodiment of the present invention. Similar to the power supply circuit  6  of the sixth embodiment, the power supply circuit  8  also comprises the pin  651 , the driver circuit  61 , and the comparison circuit  63 . The couplings and operations of these components are the same as those of the components of the power supply circuit  6  of the sixth embodiment, and thus will not be further described herein. 
     The power supply circuit  8  further comprises the selection circuit  88 , the PMOSFET  845 , the N-channel metal-oxide-semiconductor field-effect transistor (NMOSFET)  846 , the switching regulation controller  87 , and the low dropout linear regulation controller  89 . The PMOSFET  845 , the NMOSFET  846 , and the switching regulation controller  87  can form a switching regulator; while the PMOSFET  845 , the NMOSFET  846 , and the low dropout linear regulation controller  89  can form a low dropout linear regulator. In other words, the switching regulator and the low dropout linear regulator of this embodiment have a common power stage. 
     The selection circuit  88  comprises the D-type flip-flop  62 , the inverter  60 , the AND gate  840 , the error amplifier  842 , and the transmission gates  843  and  844 . The PMOSFET  845  has a source being coupled to a power supply (VDD) and a drain being coupled to a source of the NMOSFET  846 . The drain of the NMOSFET  846  is grounded. 
     The first input end of the AND gate  840  receives the inverted signal EN-SWR, the second input end of the AND gate  840  is coupled to the switching regulation controller  87 , and the output end of the AND gate  840  is coupled to the gate of the NMOSFET  846 . The transmission gates  843  and  844  are coupled to each other. The first end of the transmission gate  843  is coupled to the switching regulation controller  87  and the second end of the transmission gate  843  is coupled to a gate of the PMOSFET  845 . The transmission gates  843  and  844  have a negative inverted signal −EN-SWR therebetween. The error amplifier  842  has the input end coupled to the low dropout linear regulation controller  89  and the output end coupled to the first end of the transmission gate  844 . The second end of the transmission gate  844  is coupled to the source of the PMOSFET  845 . 
     When the inverted signal EN-SWR is at a high level, the output of the switching regulation controller  87  passes through the AND gate to turn on the NMOSFET  846 . Furthermore, another output of the switching regulation controller  87  passes through the transmission gate  843  to turn on the PMOSFET  845 . In this case, the switching regulation controller  87  generates the output signal Output as the output power for outputting to the examined circuit  65 . It is learned that when the inverted signal EN-SWR is at the high level, the switching regulator formed by the PMOSFET  845 , the NMOSFET  846 , and the switching regulation controller  87  is activated. 
     When the inverted signal EN-SWR is at a low level, the output of the switching regulation controller  87  is unable to pass through the AND gate  840 . Instead, the output of the low dropout linear regulation controller  89  controls the PMOSFET  845  and the NMOSFET  846 . In this case, the low dropout linear regulation controller  89  generates an output signal Output as an output power for outputting to the examined circuit  65 . It is learned that when the inverted signal EN-SWR is at the low level, the low dropout linear regulator formed by the PMOSFET  845 , the NMOSFET  846 , and the low dropout linear regulation controller  89  is activated. 
       FIG. 9  depicts the ninth embodiment of the present invention. In this embodiment, the comparison circuit  93  not only obtains a first detected electric value via a pin  651  but also obtains a second detected electric value via a pin  953  so as to produce the comparison result  632 . 
     According to the above embodiments, by virtue of the correlation between the impedance of a passive component and the frequency of an impulse signal, the present invention calculates a difference value between detected electric values of two ends of an examined circuit and then compares the difference value with a threshold value to produce a comparison result which indicates whether the examined circuit comprises a passive component. This technical feature can be further applied to a power supply circuit and implemented by various circuits. In this way, abnormal operations, short circuits, or burnout of the circuit can be avoided. 
     The above disclosure is related to the detailed technical contents and inventive features thereof. People skilled in this field may proceed with a variety of modifications and replacements based on the disclosures and suggestions of the invention as described without departing from the characteristics thereof. Nevertheless, although such modifications and replacements are not fully disclosed in the above descriptions, they have substantially been covered in the following claims as appended.