Abstract:
The present invention discloses a multi-purpose power management apparatus, a power path control circuit, and a control method therefor. The multi-purpose power management apparatus controls power conversion between an input power and an output power and charging operation from the output power to a battery. The multi-purpose power management apparatus includes: a switch circuit including at least one power transistor; a switch control circuit generating a PWM signal to control the power transistor, for controlling the power conversion between the input power and the output power; a charging management circuit for controlling the charging operation from the output power to the battery; and a path selection circuit for determining whether the charging operation is controlled by the charging management circuit.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of Invention 
         [0002]    The present invention relates to a multi-purpose power management apparatus, a power path control circuit and a control method therefor, in particular to such multi-purpose power management apparatus, power path control circuit and control method that automatically determine whether a charging management circuit needs to be enabled according to the connection relationship between a system load and a battery, such that the apparatus, circuit and method can be applied to different applications regardless whether the system load is directly or indirectly connected to the battery. 
         [0003]    2. Description of Related Art 
         [0004]      FIG. 1  shows a schematic diagram of a prior art power supply system. As shown in  FIG. 1 , the power supply system  10  includes a switching regulator  1   a  which converts external power from an input side Vin to power of an output side Vout. The output side Vout supplies power to the system load (which is for example a computer host) and charges a battery Batt. When the input side is disconnected from the external power, the battery Batt would output power to the output side Vout. A feedback circuit  13  includes two resistors R 1  and R 2  connected to each other in series. One terminal of the resistor R 1  is coupled to the output voltage Vout, and one terminal of the resistor R 2  is coupled to the ground. The feedback signal FB 1  is extracted from the voltage difference across the resistor R 2 . An error amplifier  11  receives the feedback signal FB 1 , and compares it with a reference voltage Vref 1  to generate an error signal Comp 1  as the input of a pulse width modulation (PWM) signal generator  12 . According to the error signal Comp 1 , the PWM signal generator  12  generates a switch signal to control an upper transistor Q 1  and a lower transistor Q 2 . The upper transistor Q 1  and the lower transistor Q 2  form a switch circuit  14 . By the operations of the transistors Q 1  and Q 2 , a current is generated through an inductor L. The output side Vout supplies a portion of the current to the battery. In order to control the charging current of the battery Batt, a sensing resistor RS is disposed between the output side Vout and the battery Batt. An error amplifier  16  detects the voltage difference between two ends of the sensing resistor RS and sends it as an input to the PWM signal generator  12 , and thereby the charging current to the battery is controlled within a predetermined range. In such prior art the error amplifier  11 , the PWM signal generator  12 , the switch circuit  14 , and the error amplifier  16  are usually integrated into a chip or an apparatus. However, the chip or the apparatus is only suitable for the configuration that the battery Batt is directly connected to the output side Vout through the sensing resistor RS, as shown in  FIG. 1 . It is not suitable for a power supply system of another configuration, such as the one shown in  FIG. 2  below. 
         [0005]    Referring to  FIG. 2 , the power supply system  20  comprises a switching regulator  1   a,  a charging management circuit  2   a,  a battery Batt, and a PMOS transistor  27 . The switching regulator  1   a  converts external power from an input side Vin to power of an output side Vout. The output side Vout supplies power to the system load (which is for example a computer host) and charges the battery Batt. When the input side is disconnected from the external power, the battery Batt would output power to the output side Vout. The power supply system  20  detects whether the battery Batt needs to be charged or it has been fully charged, and controls the PMOS transistor  27  thereby to provide or stop charging current to the battery Batt. 
         [0006]    The feedback circuit  26  includes two resistors R 3  and R 4  connected to each other in series. One terminal of the resistor R 3  is coupled to the voltage Vbatt outputted by the battery Batt, and one terminal of the resistor R 4  is coupled to the ground. An error amplifier  21  receives the feedback signal FB 2 , and compares it with a reference voltage Vref 2  to generate an error signal Comp 2 . An error amplifier  24  detects the voltage difference across the sensing resistor RS and outputs an error signal Comp 4 . An error amplifier  23  compares the error signal Comp 4  with a reference voltage Vref 3  to output an error signal Comp 3 . An adder  25  sums up the two error signals Comp 2  and Comp 3 , and outputs the sum signal to the charging controller  22 . According to the sum signal, the charging controller  22  determines whether the battery Batt needs to be charged or it has been fully charged, and controls the PMOS transistor  27  thereby. 
         [0007]    In such prior art the error amplifier  11 , the PWM signal generator  12 , the switch circuit  14 , the error amplifiers ( 21 ,  23 ,  24 ), the charging controller  22 , and the adder  25  are usually integrated into a chip or a power management apparatus  2   d.  However, the power management apparatus is only suitable for the configuration that the battery Batt is connected to the output side Vout through the sensing resistor RS and the PMOS transistor  27 , as shown in  FIG. 2 . It can not be applied to a power supply system of another configuration, such as the one without the power transistor  27  as shown in  FIG. 1 . 
         [0008]    In view of above, the present invention overcomes the foregoing drawbacks by providing a multi-purpose power management apparatus, a power path control circuit and a control method therefor. Such multi-purpose power management apparatus, power path control circuit and control method can automatically determine whether a charging management circuit needs to be enabled according to the connection relationship between a system load and a battery, such that the apparatus, circuit and method can be applied to different applications regardless whether the system load is directly or indirectly connected to the battery through a switch. 
       SUMMARY OF THE INVENTION 
       [0009]    An objective of the present invention is to provide a multi-purpose power management apparatus. 
         [0010]    Another objective of the present invention is to provide a charging path control circuit. 
         [0011]    Another objective of the present invention is to provide a method for controlling power paths. 
         [0012]    To achieve the foregoing objectives, in one aspect, the present invention provides a multi-purpose management apparatus controlling power conversion from input power to output power and controlling charging operation to a battery from the output power, the multi-purpose management apparatus comprising: a switch circuit including at least one first power transistor; a switch control circuit generating a switch signal operating the power transistor to control the power conversion from the input power to the output power; a charging management circuit for controlling the charging operation from the output power to the battery; and a path selection circuit determining whether the charging operation to the battery is controlled by the charging management circuit. 
         [0013]    In the foregoing multi-purpose management apparatus, when the output power is coupled to the battery through a second power transistor, the path selection circuit designates the charging management circuit to operate the second power transistor for controlling the charging operation to the battery; when the output power is not coupled to the battery through the second power transistor, the path selection circuit does not designate the charging management circuit to control the charging operation to the battery. 
         [0014]    In one embodiment, the path selection circuit includes a multiplexer which determines whether the charging operation is controlled by the charging management circuit according to an external setting signal. 
         [0015]    In another embodiment, the charging management circuit generates an output signal outputted through a pin, and the path selection circuit includes: a detection signal generator generating a detection signal outputted through the pin to generate a detection voltage; a comparator comparing the detection voltage with a reference voltage; and a multiplexer determining whether the charging operation to the battery is controlled by the charging management circuit according to an output from the comparator. 
         [0016]    In one embodiment, the charging management circuit includes a first error amplifier generating a first error signal according to information related to a battery charging current, and the path selection circuit determines to transmit the first error signal to the switch control circuit or the charging management circuit. 
         [0017]    In yet another aspect, the present invention provides a charging path control circuit for selecting at least one control loop according to a connection relationship between an output power and a battery, the charging path control comprising: a charging management circuit for controlling a charging operation to the battery from the output power; and a path selection circuit determining whether the charging operation to the battery is controlled by the charging management circuit according to whether or not a power transistor is coupled between the output power and the battery. 
         [0018]    In yet another aspect, the present invention provides a power path control method, comprising: converting an input power to an output power; performing a charging operation to a battery from the output power through a charging path; detecting whether a power transistor is disposed on the charging path; controlling the charging operation to the battery by controlling the power transistor when the power transistor is disposed on the charging path; and controlling the charging operation to the battery by controlling the conversion between the input power and the output power when the power transistor is not disposed on the charging path. 
         [0019]    Preferably, the power path control method further comprises: detecting a current on the charging path to generate information related to a battery charging current; feeding back the information to control the power transistor when the power transistor is disposed on the charging path; and feeding back the information to control the conversion between the input power and the output power when the power transistor is not disposed on the charging path. 
         [0020]    In the foregoing power path control method, the step of detecting whether the power transistor is disposed on the charging path preferably comprises: providing a pin for connecting to a gate terminal of the power transistor or to ground; generating a detection signal outputted through the pin to generate a detection voltage; and comparing the detection voltage with a reference to determine whether the power transistor exists. 
         [0021]    The objectives, technical details, features, and effects of the present invention will be better understood with regard to the detailed description of the embodiments below, with reference to the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  shows a schematic diagram of a prior art power supply system. 
           [0023]      FIG. 2  shows a schematic diagram of another prior art power supply system. 
           [0024]      FIG. 3  shows a schematic diagram of an embodiment of the present invention, illustrating a multi-purpose management apparatus applied to a power supply system. 
           [0025]      FIG. 4  shows a schematic diagram of the multi-purpose management apparatus in  FIG. 3  applied to another power supply system. 
           [0026]      FIG. 5  shows another embodiment of the path selection circuit  3   c.    
           [0027]      FIGS. 6A-6B  show two embodiments illustrating examples of the detection signal generator  33 . 
           [0028]      FIGS. 7A-7B  show two other embodiments illustrating examples of the detection signal generator  33 . 
           [0029]      FIG. 8  shows a schematic diagram of another embodiment of the present invention, illustrating a multi-purpose management apparatus applied to a power supply system. 
           [0030]      FIG. 9  shows a schematic diagram of the multi-purpose management apparatus in  FIG. 8  applied to another power supply system. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0031]    The drawings as referred to throughout the description of the present invention are for illustration only, to show the functions of the devices and the signal interrelationships between the devices, but not drawn according to actual dimensions or scales. 
         [0032]    Referring to  FIGS. 3 and 4 , these figures show that the multi-purpose management apparatus  3   d  of the present invention can be applied to different applications to match with different printed circuit boards in use. It is suitable for the configuration that the battery Batt is connected to the output side Vout through the sensing resistor RS, as shown in  FIG. 1 , and is also suitable for the configuration that the battery Batt is connected to the output side Vout through the sensing resistor RS and the PMOS transistor  27 , as shown in  FIG. 2 . Examples of such applications are respectively shown in  FIGS. 3 and 4 . The multi-purpose management apparatus  3   d  can detect which configuration it is applied to by various aways. In one embodiment, this can be manually set by an external signal. In another embodiment, the multi-purpose management apparatus  3   d  has a pin which is designed for connecting to the transistor  27  in one configuration, and the potential of this pin can be used to automatically detect which configuration the multi-purpose management apparatus  3   d  is connected to. 
         [0033]    Referring to  FIG. 3 , the power supply system  30  comprises a switching regulator  3   a,  a charging management circuit  3   b,  a battery Batt, a transistor  27  (shown to be a PMOS transistor as an example; it can be an NMOS transistor instead), and a path selection circuit  3   c.  The switching regulator  3   a  controls the power conversion from an input side Vin to an output side Vout. The charging management circuit  3   b  controls the charging operation of the battery Batt. The path selection circuit  3   c  designates the information of the charging current of the battery Batt to be fed back to the switching regulator  3   a  or the charging management circuit  3   b  according to whether the transistor  27  is disposed between the output side Vout and the battery Batt. 
         [0034]    More specifically, the switching regulator  3   a  converts the external power from an input side Vin to an output side Vout. The output side Vout supplies power to the system load and charges the battery Batt. When the input side is disconnected from the external power, the battery Batt would output power to the output side Vout. The power supply system  30  detects whether the battery Batt needs to be charged or it has been fully charged, and controls the PMOS transistor thereby to provide or stop the charging current to the battery Batt. 
         [0035]    A feedback circuit  13  includes two resistors R 1  and R 2  connected to each other in series. One terminal of the resistor R 1  is coupled to the output voltage Vout, and one terminal of the resistor R 2  is coupled to the ground. The feedback signal FB 1  is the voltage difference between two ends of the resistor R 2 . In the switching regulator  3   a,  an error amplifier  11  receives the feedback signal FB 1 , and compares it with a reference voltage Vref 1  to generate an error signal Comp 1  as an input to a PWM signal generator  12 . According to the error signal Comp 1 , the PWM signal generator  12  generates a switch signal to control an upper transistor Q 1  and a lower transistor Q 2 . The upper transistor Q 1  and the lower transistor Q 2  form a switch circuit  14 . By the operations of the transistors Q 1  and Q 2 , a current is generated through an inductor L. The output side Vout supplies a portion of the current to charge the battery. As shown in  FIG. 3 , because the PMOS transistor  27  is disposed between the output side Vout and the battery Batt, the multiplexer  32  of the path selection circuit  3   c  selects the output path to an adder  25  rather than the output path to an adder  34  (the details of the path selection circuit  3   c  will be explained below), so the adder  34  of the switching regulator  3   a  receives the error signal Comp 1  only. The error amplifier  11 , the adder  34 , and the PWM signal controller  12  form a switch control circuit  15 . 
         [0036]    A feedback circuit  26  includes two resistors R 3  and R 4  connected to each other in series. One terminal of the resistor R 3  is coupled to the output voltage Vbatt of the battery Batt, and one terminal of the resistor R 4  is coupled to the ground. In the charging management circuit  3   b,  an error amplifier  21  receives the feedback signal FB 2 , and compares it with a reference voltage Vref 2  to generate an error signal Comp 2 . An error amplifier  24  detects the voltage difference across the sensing resistor RS and outputs an error signal Comp 4 . An error amplifier  23  compares the error signal Comp 4  with a reference voltage Vref 3  to output an error signal Comp 3 . Because the multiplexer  32  of the path selection circuit  3   c  selects the output path to the adder  25 , the two error signals Comp 2  and Comp 3  is summed up by the adder  25 , and the sum signal is outputted to the charging controller  22 . The sum signal represents the information of the battery voltage and the charging current of the battery Batt. According to the sum signal, the charging controller  22  determines whether the battery Batt needs to be charged or it has been fully charged, and outputs a signal PPCTRL to control the PMOS transistor  27  thereby. 
         [0037]    In this embodiment, the path selection circuit  3   c  includes a comparator  31 , a multiplexer  32  and a detection signal generator  33 . The detection signal generator  33  generates a detection signal transmitted through the output node PPCTRL of the charging controller  22  and the pin P, to detect the status of the external connection with the pin P. As shown in  FIG. 3 , because the pin P is connected to the PMOS transistor  27 , the detection signal generated from the detection signal generator  33  causes the node PPCTRL to have a relatively higher voltage. The negative input terminal of the comparator  31  receives the voltage resulted from the detection signal, and the comparator  31  compares it with a reference voltage Vref 4  to output a control signal to the multiplexer  32  such that a transmission path is selected for the error signal Comp 3 . The path selection circuit  3   c  sets the path selection preferably only when the system just starts or reboots, so that the output signal PPCTRL of the charging controller  22  does not affect the path selection circuit  3   c  when the system  30  is in a normal operation status. In one embodiment, when the power supply system  30  is turned on, a POR (Power-On-Reset) signal is generated and it can be used as an enable signal to control the comparator  31  and/or the detection signal generator  33 . After the system  30  is completely turned on, the comparator  31  and/or the detection signal generator  33  is disable, so the selection made by the multiplexer  32  is fixed, and will not be interfered by the variation of the signal PPCTRL. 
         [0038]    Compared with  FIG. 3 , the system load of the power supply system  40  in  FIG. 4  is connected to the battery Batt through only the sensing resistor RS without the PMOS transistor  27  in between, and hence, the pin P for outputting the signal PPCRRL from the charging controller  22  is grounded. The negative input terminal of the comparator  31  is also coupled to the ground. The comparator  31  compares its negative input with the reference voltage Vref 4 , and outputs a control signal to the multiplexer  32  so that the multiplexer  32  selects to send the error signal Comp 3  to the adder  34 . The adder  34  sums up the error signals comp 1  and comp 3 , and outputs the sum to the PWM controller  12 . In one embodiment, the switch control circuit  15 , the switch circuit  14 , the error amplifiers ( 11 ,  21 ,  23 ,  24 ), the charging controller  22 , the adders ( 25 ,  34 ), and the path selection circuit  3   c  can be integrated into a chip or a multi-purpose power management apparatus  3   d.  Moreover, the chip or the apparatus is suitable for the application wherein the battery Batt is connected to the output side Vout through the PMOS transistor  27  and the sensing resistor RS, as shown in  FIG. 3 , and is also suitable for the application that the battery Batt is connected to the output side Vout through the sensing resistor RS only, as shown in  FIG. 4 . However, the circuits and the devices included in the multi-purpose power management apparatus are not limited by the above embodiment. For example, if the operation power of the transistors in the switch circuit  14  is too high, they can be moved to outside of the multi-purpose power management apparatus  3   d  and are not integrated therein. 
         [0039]    The foregoing embodiment is an example to illustrate that the path selection circuit  3   c  can automatically detect whether the transistor  27  is disposed in the charging path to the battery Batt, and determine to feed back the charging current information of the battery Batt to the switching regulator  3   a  or the charging management circuit  3   b  accordingly. However, this is not the only way to make the path selection. As shown in  FIG. 5 , another way is to provide a setting signal from the external of the chip or the apparatus, to set the feedback path of the charging current information of the battery Batt. In this embodiment, the path selection circuit  3   c  can only include the multiplexer  32 . 
         [0040]      FIGS. 6A-6B  show two embodiments illustrating examples of the detection signal generator  33 . For example, the detection signal generator  33  can be a weak current source or a resistor. Its upper terminal is connected to a suitable voltage (such as a chip operation voltage VDD, but is not limited to this), and its lower terminal is coupled to the output node PPCTRL (pin P) of the charging controller  22 . When the system starts or reboots, if the pin P is coupled to the PMOS transistor  27 , the detection signal generator  33  can raise the voltage of the node PPCTRL. On the other hand, if the pin P is grounded, the detection signal generator  33  cannot raise the voltage of the node PPCTRL. When the system is in a normal operation status, the voltage of the node PPCTRL is dominated by the output of the charging controller  22 , and is not affected by the detection signal generator  33 . 
         [0041]      FIGS. 7A-7B  show two other embodiments illustrating examples of the detection signal generator  33 . In the two embodiments, the detection signal generator  33  further includes a switch SW which is turned on by the power-on reset signal POR. When the system enters the normal operation status after booting, the switch SW is turned OFF to reduce power consumption. 
         [0042]    Referring  FIGS. 8 and 9 , these figure show another embodiment of the present invention which is also suitable for the applications of various connections between the system load and the battery. Compared with  FIGS. 3 and 4 , this embodiment further comprises error amplifiers  55  and  56  to respectively control a switching regulator  5   a  and a charging management circuit  5   b  for better accuracy. The parts similar to the embodiment in  FIGS. 3 and 4  are not further explained below. 
         [0043]    Referring to  FIG. 8 , the power supply system  50  comprises a switching regulator  5   a,  a charging management circuit  5   b,  a battery Batt, a PMOS transistor  27 , and a path selection circuit  3   c.  The multiplexer  32  of the path selection circuit  3   c  designates the error signal Comp 3  to be transmitted to the error amplifier  55  or  56 . The error amplifier  55  compares the error signal Comp 3  with a reference voltage Vref 5  to output an error signal Comp 5 . The adder  34  sums up the error signals Comp 1  and comp 5 , and output the sum to the PWM controller  12 . Similarly, the error amplifier  56  compares the error signal Comp 3  with a reference voltage Vref 6  to output an error signal Comp 6 . The adder  25  sums up the error signals Comp 2  and comp 6 , and output the sum to the charging controller  22 . The difference between  FIG. 8  and  FIG. 3  is that the signal Comp 3  representing the information of the charging current of the battery Batt is not inputted to the adder  25  or  34  in the same form of the same value. The signal Comp 3  is compared with the reference voltage Vref 5  or the reference voltage Vref 6  to generate the error signal Comp 5  or the error signal Comp 6 , and the error signal Comp 5  or the error signal Comp 6  is inputted to the adder  34  or the adder  25  correspondingly. In this way, the switch circuit  14  and the PMOS transistor  27  can be respectively controlled for better accuracy. 
         [0044]    Compared with  FIG. 8 , the system load of the power supply system  60  in  FIG. 9  is connected to the battery Batt through the sensing resistor RS without the PMOS transistor in between, and hence, the pin P for outputting the signal PPCRRL of the charging controller  22  is coupled to the ground. The detection signal outputted by the detection signal generator  33  results in a different voltage at the output node PPCTRL of the charging controller  22  in response to the non-existence of the PMOS transistor  27 . After the comparator  31  checks the voltage, the multiplexer  32  can select a proper path. The error amplifiers ( 11 ,  55 ), the adder  34 , and the PWM signal controller  12  form a switch control circuit  15 ′. 
         [0045]    In one embodiment, the switch control circuit  15 ′, the switch circuit  14 , the error amplifiers ( 11 ,  21 ,  23 ,  24 ,  55 ,  56 ), the charging controller  22 , the adders ( 25 ,  34 ), and the path selection circuit  3   c  can be integrated into a chip or a multi-purpose power management apparatus  5   d.  Moreover, the chip or the apparatus is suitable for the application wherein the battery Batt is connected to the output side Vout through the PMOS transistor  27  and the sensing resistor RS, as shown in  FIG. 8 , and is also suitable for the application wherein the battery Batt is connected to the output side Vout through the sensing resistor RS only, as shown in  FIG. 9 . 
         [0046]    The present invention has been described in considerable detail with reference to certain preferred embodiments thereof. It should be understood that the description is for illustrative purpose, not for limiting the scope of the present invention. Those skilled in this art can readily conceive variations and modifications within the spirit of the present invention. For example, the present invention is also applicable to the configuration wherein there is no resistor RS between the output side Vout and the battery Batt for sensing the charging current of the battery Batt (that is, the output side Vout is directly connected to the battery Batt). The multipurpose power management apparatus  3   d  or  5   d  of the present invention can be applied to such configuration if the input of the error amplifier  24  is grounded or floating. Thus, the present invention should cover all such and other modifications and variations, which should be interpreted to fall within the scope of the following claims and their equivalents.