Abstract:
A package structure integrating a start-up component, a controller, and a power switch for a power converter, wherein the power converter has a coil having a first end and a second end, and the first end is coupled to a rectifier, the package structure including: a first die pad for carrying a chip of the controller; a second die pad for carrying a chip of the start-up component and a chip of the power switch, wherein the chip of the start-up component has a bottom surface providing a first drain contact; and the chip of the power switch has a bottom surface providing a second drain contact; and a plurality of external connection leads, of which one is connected with the second die pad via a wire and is used to couple with the second end of the coil.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a package structure of a controller module for power conversion applications, especially to a package structure of a controller module including a start-up component, a controller, and a power switch. 
         [0003]    2. Description of the Related Art 
         [0004]    Please refer to  FIG. 1   a,  which illustrates a circuit diagram of a prior art power converter, and  FIG. 1   b,  which illustrates the package structure of a controller module applicable in the prior art power converter of  FIG. 1   a.  As illustrated in  FIG. 1   a,  the prior art power converter includes a PWM (pulse width modulation) controller  100 , a first NMOS (n type metal oxide semiconductor) transistor  110 , a second NMOS transistor  120 , a primary coil  130  for transferring power to a load, and an auxiliary coil  140  for generating a supply voltage V CC ; and in  FIG. 1   b,  the controller module is in the form of an integrated circuit package having a package structure integrating a chip  100   c  of the PWM controller  100 , a chip  110   c  of the first NMOS transistor  110 , and a chip  120   c  of the second NMOS transistor  120  of  FIG. 1   a.    
         [0005]    The PWM controller  100  has two contacts for connecting with the first NMOS transistor  110 , one contact for connecting with the supply voltage V CC , and one contact for providing a PWM signal V PWM  to switch on/off the second NMOS transistor  120  for realizing a power conversion. 
         [0006]    The first NMOS transistor  110 , having a first drain coupled to a first end A of the primary coil  130 , a first gate connected to one contact of the PWM controller  100 , and a first source connected to another contact of the PWM controller  100 , is used as a start-up component, which is switched on to provide a current path for starting up the PWM controller  100  during an initial period after an AC power V AC  is applied, and is switched off by the PWM controller  100  when the supply voltage V CC  is built up. That is, when the supply voltage V CC  reaches a predetermined level, the PWM controller  100  will send a low voltage to the first gate of the first NMOS transistor  110  to switch off the first NMOS transistor  110 . 
         [0007]    The second NMOS transistor  120 , acting as a power switch, has a second drain coupled to a second end B of the primary coil  130 , a second gate coupled with the PWM signal V PWM , and a second source connected with a current sensing resistor for generating a current sensing signal V CS  according to a primary current I P . The second NMOS transistor  120  controls an on period for the primary current I P  to flow through the primary coil  130  in response to the PWM signal V PWM . 
         [0008]    The package structure in  FIG. 1   b  includes the chip  100   c  of the PWM controller  100 , the chip  110   c  of the first NMOS transistor  110 , the chip  120   c  of the second NMOS transistor  120 , a resin material  200 , a first die pad  210 , a second die pad  220 , a third die pad  230 , and eight external connection leads. 
         [0009]    The resin material  200  is used to enclose the chip  100   c  of the PWM controller  100 , the chip  110   c  of the first NMOS transistor  110 , the chip  120   c  of the second NMOS transistor  120 , the first die pad  210 , the second die pad  220 , and the third die pad  230 . 
         [0010]    The first die pad  210  is made of a conductor, copper for example, for carrying the chip  110   c  of the first NMOS transistor  110 . The chip  110   c  of the first NMOS transistor  110  has a top surface providing a gate contact G 1  and a source contact S 1 , and a bottom surface providing a drain contact D 1  which is electrically connected with the first die pad  210 . 
         [0011]    The second die pad  220  is made of a conductor, copper for example, for carrying the chip  100   c  of the PWM controller  100 . 
         [0012]    The third die pad  230  is made of a conductor, copper for example, for carrying the chip  120   c  of the second NMOS transistor  120 . The chip  120   c  of the second NMOS transistor  120  has a top surface providing a gate contact G 2  and a source contact S 2 , and a bottom surface providing a drain contact D 2  which is electrically connected with the third die pad  230 . 
         [0013]    The interconnections among the chip  100   c,  the chip  110   c,  the chip  120   c,  and the external connection leads are accomplished by wires, which can be made of copper, gold, or aluminum. As can be seen in  FIG. 1   b,  a wire  251  connects the first die pad  210  with an external connection lead  241  of the eight external connection leads, and a wire  252  connects the third die pad  230  with an external connection lead  242  of the eight external connection leads, wherein the external connection lead  241  is used to connect electrically with the first end A of the primary coil  130 , and the external connection lead  242  is used to connect electrically with the second end B of the primary coil  130 . 
         [0014]    As the die pads constitute a substantial portion of the cost of the package structure of the controller module, it is therefore desirable to reduce the number of die pads to promote the market competition ability of the controller module. However, as can be seen in  FIG. 1   a  and  FIG. 1   b,  the first die pad  210 , the second die pad  220 , and the third die pad  230  all seem to be necessary for implementing the controller module. For example, if we put the chip  110   c  and the chip  120   c  into one die pad to save one die pad, then the drain contact D 1  will be in direct electrical contact with the drain contact D 2 , making the power module not applicable for the prior art power converter of  FIG. 1   a.  Therefore, it is not easy to reduce the cost of the package structure of the controller module for power converters. 
       SUMMARY OF THE INVENTION 
       [0015]    One objective of the present invention is to disclose a package structure of a controller module, which can reduce the number of die pads used in the package structure. 
         [0016]    Another objective of the present invention is to disclose a package structure of a controller module, which can provide a freedom of two ways of ending a start-up period for a power converter. 
         [0017]    Still another objective of the present invention is to disclose a package structure of a controller module, which can reduce the cost of the controller module. 
         [0018]    To attain the foregoing objectives, the present invention proposes a package structure integrating a start-up component, a controller, and a power switch for a power converter, wherein the power converter has a coil for transferring power, the coil has a first end and a second end, and the first end is coupled to a rectifier, the package structure including: 
         [0019]    a first die pad made of a conductor, used for carrying a chip of the controller; 
         [0020]    a second die pad made of the conductor, used for carrying a chip of the start-up component and a chip of the power switch, wherein the chip of the start-up component has a top surface providing a first gate contact and a first source contact, and a bottom surface providing a first drain contact which is electrically connected with the second die pad; and the chip of the power switch has a top surface providing a second gate contact and a second source contact, and a bottom surface providing a second drain contact which is electrically connected with the second die pad; 
         [0021]    a plurality of external connection leads, wherein one of the plurality of external connection leads is connected with the second die pad via a wire and is used to couple with the second end of the coil; and 
         [0022]    a resin material, used to enclose the chip of the controller, the chip of the start-up component, the chip of the power switch, the first die pad, and the second die pad. 
         [0023]    In one embodiment, the controller is a PWM controller, the start-up component is a first NMOS transistor, and the power switch is a second NMOS transistor. 
         [0024]    In one embodiment, the conductor is copper. 
         [0025]    In one embodiment, the wire is made of a material selected from a group consisting of copper, gold, and aluminum. 
         [0026]    To attain the foregoing objectives, the present invention proposes another package structure integrating a start-up component, a controller, and a power switch for a power converter, wherein the power converter has a coil for transferring power, the coil has a first end and a second end, and the first end is coupled to a rectifier, the package structure comprising: 
         [0027]    a first die pad made of a conductor, used for carrying a chip of the start-up component and a chip of the power switch, wherein the chip of the start-up component has a top surface providing a first gate contact and a first source contact, and a bottom surface providing a first drain contact which is electrically connected with the first die pad; and the chip of the power switch has a top surface providing a second gate contact and a second source contact, the second source contact being used to carry the controller, and a bottom surface providing a second drain contact which is electrically connected with the first die pad; 
         [0028]    a plurality of external connection leads, wherein one of the plurality of external connection leads is connected with the first die pad via a wire and is used to couple with the second end of the coil; and 
         [0029]    a resin material, used to enclose the chip of the controller, the chip of the start-up component, the chip of the power switch, and the first die pad. 
         [0030]    In one embodiment, the controller is a PWM controller, the start-up component is a first NMOS transistor, and the power switch is a second NMOS transistor. 
         [0031]    In one embodiment, the conductor is copper. 
         [0032]    In one embodiment, the wire is made of a material selected from a group consisting of copper, gold, and aluminum. 
         [0033]    To make it easier for our examiner to understand the objectives, structure, innovative features, and performance of the invention, we use preferred embodiments together with the accompanying drawings for the detailed description of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]      FIG. 1   a  illustrates a circuit diagram of a prior art power converter. 
           [0035]      FIG. 1   b  illustrates a package structure of a controller module applicable in the prior art power converter of  FIG. 1   a.    
           [0036]      FIG. 2   a  illustrates a circuit diagram of a power converter using a controller module of the present invention. 
           [0037]      FIG. 2   b  illustrates a preferred embodiment of the package structure of a controller module applicable in the power converter of  FIG. 2   a.    
           [0038]      FIG. 2   c  illustrates another preferred embodiment of the package structure of a controller module applicable in the power converter of  FIG. 2   a.    
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0039]    The present invention will be described in more detail hereinafter with reference to the accompanying drawings that show the preferred embodiments of the invention. 
         [0040]    To solve the problem mentioned above, the present invention rearranges the start-up circuit of the power converter to make the first drain of the first NMOS transistor and the second drain of the second NMOS transistor share a common contact, so as to reduce the die pad number of the package structure of the controller module. 
         [0041]    Please refer to  FIG. 2   a,  which illustrates a circuit diagram of a power converter using a controller module of the present invention. As illustrated in  FIG. 2   a,  the power converter includes a PWM controller  300 , a first NMOS transistor  310 , a second NMOS transistor  320 , a primary coil  330  having a first end A and a second end B, the first end A being coupled to a rectifier, and an auxiliary coil  340  for generating a supply voltage V CC . 
         [0042]    The PWM controller  300  has a first contact and a second contact for connecting with the first NMOS transistor  310 , and a third contact for providing a PWM signal V PWM  to switch on/off the second NMOS transistor  320  for realizing a power conversion. 
         [0043]    The first NMOS transistor  310 , having a first drain coupled to the second end B of the primary coil  330 , a first gate coupled with the first contact of the PWM controller  300 , and a first source coupled with the second contact of the PWM controller  300  and with the supply voltage V CC , is used as a start-up component, which is switched on to provide a current path for starting up the PWM controller  300  during an initial period after an AC power V AC  is applied, and is switched off when the supply voltage V CC  is built up, wherein the first NMOS transistor  310  can be shut down sorely by the supply voltage V CC  when the supply voltage V CC  reaches a predetermined voltage value to cause the gate-source voltage of the first NMOS transistor  310  to be smaller than a threshold, or shut down by the PWM controller  300  which applies a low voltage to the first gate of the first NMOS transistor  310  when the supply voltage V CC  reaches the predetermined voltage value. 
         [0044]    The second NMOS transistor  320 , acting as a power switch, has a second drain coupled to the second end B of the primary coil  330 , a second gate coupled with the PWM signal V PWM , and a second source connected with a current sensing resistor for generating a current sensing signal V CS  according to a primary current I P . The second NMOS transistor  320  controls an on period for the primary current I P  to flow through the primary coil  330  in response to the PWM signal V PWM . 
         [0045]    Please refer to  FIG. 2   b,  which illustrates a preferred embodiment of the package structure of a controller module applicable in the power converter of  FIG. 2   a.  The package structure in  FIG. 2   b  includes a chip  300   c  of the PWM controller  300 , a chip  310   c  of the first NMOS transistor  310 , a chip  320   c  of the second NMOS transistor  320 , a resin material  400 , a first die pad  410 , a second die pad  420 , and eight external connection leads. 
         [0046]    The resin material  400  is used to enclose the chip  300   c  of the PWM controller  300 , the chip  310   c  of the first NMOS transistor  310 , the chip  320   c  of the second NMOS transistor  320 , the first die pad  410 , and the second die pad  420 . 
         [0047]    The first die pad  410  is made of a conductor, copper for example, for carrying the chip  300   c  of the PWM controller  300 . 
         [0048]    The second die pad  420  is made of a conductor, copper for example, for carrying the chip  310   c  of the first NMOS transistor  310  and the chip  320   c  of the second NMOS transistor  320 . The chip  310   c  of the first NMOS transistor  310  has a top surface providing a first gate contact G 1  and a first source contact S 1 , and a bottom surface providing a first drain contact D 1  which is electrically connected with the second die pad  420 . The chip  320   c  of the second NMOS transistor  320  has a top surface providing a second gate contact G 2  and a second source contact S 2 , and a bottom surface providing a second drain contact D 2  which is electrically connected with the second die pad  420  and thereby electrically connected with the first drain contact D 1 . 
         [0049]    The interconnections among the chip  300   c,  the chip  310   c,  the chip  320   c,  and the external connection leads are accomplished by wires, which can be made of copper, gold, or aluminum. As can be seen in  FIG. 2   b,  a wire  441  connects the second die pad  420  with an external connection lead  431  of the eight external connection leads, the external connection lead  431  being used to connect electrically with the second end B of the primary coil  330 . To keep the figure easy to read, wire connections for other external connection leads are omitted in the figure because they are not the focus of the present invention. 
         [0050]    Thanks to a novel arrangement of the start-up circuit of the power converter in  FIG. 2   a,  the first drain of the first NMOS transistor  310  and the second drain of the second NMOS transistor  320  can share a common contact (the second end B of the primary coil  330 ), and the chip  310   c  of the first NMOS transistor  310  and the chip  320   c  of the second NMOS transistor  320  can therefore be placed on a same die pad (the second die pad  420 ) of the package structure of the controller module in  FIG. 2   b  to reduce the die pad number, and thereby cut down the cost of the package structure of the controller module. 
         [0051]    Please refer to  FIG. 2   c,  which illustrates another preferred embodiment of the package structure of a controller module applicable in the power converter of  FIG. 2   a.  The package structure in  FIG. 2   c  includes a chip  300   c  of the PWM controller  300 , a chip  310   c  of the first NMOS transistor  310 , a chip  320   c  of the second NMOS transistor  320 , a resin material  500 , a first die pad  510 , and eight external connection leads. 
         [0052]    The resin material  500  is used to enclose the chip  300   c  of the PWM controller  300 , the chip  310   c  of the first NMOS transistor  310 , the chip  320   c  of the second NMOS transistor  320 , and the first die pad  510 . 
         [0053]    The first die pad  510  is made of a conductor, copper for example, for carrying the chip  310   c  of the first NMOS transistor  310  and the chip  320   c  of the second NMOS transistor  320 , and the chip  300   c  of the PWM controller  300  is placed on a second source contact area S 2  of the chip  320   c,  wherein the chip  300   c  has an insulating bottom surface in contact with the second source contact area S 2 . 
         [0054]    The chip  310   c  of the first NMOS transistor  310  has a top surface providing a first gate contact G 1  and a first source contact S 1 , and a bottom surface providing a first drain contact D 1  which is electrically connected with the first die pad  510 . The chip  320   c  of the second NMOS transistor  320  has a top surface providing a second gate contact G 2  and the second source contact S 2 , and a bottom surface providing a second drain contact D 2  which is electrically connected with the first die pad  510  and thereby electrically connected with the first drain contact D 1 . 
         [0055]    The interconnections among the chip  300   c,  the chip  310   c,  the chip  320   c,  and the external connection leads are accomplished by wires, which can be made of copper, gold, or aluminum. As can be seen in  FIG. 2   c,  a wire  531  connects the first die pad  510  with an external connection lead  521  of the eight external connection leads, the external connection lead  521  being used to connect electrically with the second end B of the primary coil  330 . To keep the figure easy to read, wire connections for other external connection leads are omitted in the figure because they are not the focus of the present invention. 
         [0056]    Apart from the embodiments illustrated above, the chip  300   c  of the PWM controller  300  can also be directly placed on the first die pad  510 , as long as the electrical insulation between the PWM controller  300  and the first die pad  510  is well ensured. 
         [0057]    With the designs elaborated above, the present invention possesses the following advantages: 
         [0058]    1. The package structure of the controller module of the present invention is capable of reducing the number of die pads. 
         [0059]    2. The package structure of the controller module of the present invention is capable of providing a freedom of two ways of ending the start-up period of a power converter. 
         [0060]    3. The package structure of the controller module of the present invention is capable of reducing the cost of the controller module. 
         [0061]    While the invention has been described by way of example and in terms of preferred embodiments, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures. 
         [0062]    In summation of the above description, the present invention herein enhances the performance over the conventional structure and further complies with the patent application requirements and is submitted to the Patent and Trademark Office for review and granting of the commensurate patent rights.