# Patent

## Title
Stackable electronic component

## Abstract

An embodiment of an electronic component includes a circuit element disposed within a package, which includes a surface and at least one standoff protruding from the surface. For example, where the circuit element is an inductor in a power supply, the standoff may allow one to mount the inductor component over another component, such as a transistor component. Therefore, the layout area of such a power supply may be smaller than the layout area of a power supply in which the inductor and transistor components are mounted side by side.

## Background
CLAIM OF PRIORITY
This application claims priority to U.S. Provisional Application Ser. No. 60/967,151 filed on Aug. 31, 2007, which is incorporated by reference.


SUMMARY
This Summary is provided to introduce, in a simplified form, a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
An embodiment of an electronic component includes a package and a circuit element disposed within the package, which includes a surface and a standoff protruding from the surface.
For example, where the circuit element is an inductor in a power supply, the standoff may allow one to mount the inductor component over another component, such as a transistor component. Therefore, the layout area of such a power supply may be smaller than the layout area of a power supply in which the inductor and transistor components are mounted side by side.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of an embodiment of a power supply having one or more phases.
FIGS. 2A-2C are respective side, bottom, and schematic views of an embodiment of a transistor component that may be used in the power supply of FIG. 1.
FIG. 3A is a perspective view of a portion of an embodiment of the power supply of FIG. 1, the portion including an inductor component stacked over transistor components that are similar to the transistor component of FIGS. 2A-2C.
FIG. 3B is a side view of the power-supply portion of FIG. 3A.
FIG. 4 is a side view of another embodiment of the power-supply portion of FIGS. 3A and 3B.
FIGS. 5 and 6 are side views of respective other embodiments of the power-supply portion of FIGS. 3A and 3B.
FIG. 7 is a perspective view of a portion of another embodiment of a power supply according to the schematic diagram of FIG. 1.
FIG. 8 is a block diagram of an embodiment of a computer system having one or more power supplies that include one or more of the power-supply portions of FIGS. 3-6.



DETAILED DESCRIPTION
FIG. 1 is a schematic diagram of an embodiment of a power supply 10, here a buck converter, which provides a regulated output voltage Vout and which includes one or more phase paths (alternatively “phases”) 121-12n each having a respective high-side drive transistor 141-14n, a respective low-side drive transistor 161-16n, and a respective inductor L1-Ln. As discussed below in conjunction with FIGS. 3-7, the inductors L1-Ln may be part of an inductor component 18, which may be stackable over one or more other components such as components that include the transistors 14 and 16. Such stacking of components may reduce the area occupied by the power supply 10 as compared to prior power supplies in which the components are not stacked, but are instead laid out side by side.
In addition to the transistors 14 and 16 and the inductor component 18, the power supply 10 includes current sensors 201-20n, a power-supply controller 22, a filter capacitor 24, and an optional filter inductor 26. An inductor L and the high-side and low-side transistors 14 and 16 coupled to the inductor at a phase intermediate node INT compose a respective phase 12. For example, the inductor L1 and the transistors 141 and 161 compose the phase 121.
The high-side transistors 141-14n, which are each switched “on” and “off” by the controller 22, are power NMOS transistors that are respectively coupled between input voltages VIN1-VINn and the nodes INT1-INTn. Alternatively, the transistors 141-14n may be other than power NMOS transistors, and may be coupled to a common input voltage. Moreover, the transistors 141-14n may be integrated on the same die as the controller 22, may be integrated on a same die that is separate from the die on which the controller is integrated, or may be disposed on discrete transistor components as discussed below in conjunction with FIGS. 2A-7.
Similarly, the low-side transistors 161-16n, which are each switched on and off by the controller 22, are power NMOS transistors that are respectively coupled between low-side voltages VL1-VLn and the nodes INT1-INTn of the inductors L1-Ln. Alternatively, the transistors 161-16n may be other than power NMOS transistors, and may be coupled to a common low-side voltage such as ground. Moreover, the transistors 161-16n may be integrated on the same die as the controller 22, may be integrated on a same die that is separate from the die on which the controller is integrated, may be integrated on a same die as the high-side transistors 161-16n, may be integrated on respective dies with the corresponding high-side transistors 161-16n (e.g., transistors 141 and 161 on a first die, transistors 142 and 162 on a second die, and so on), or may be disposed on discrete transistor components as discussed below in conjunction with FIGS. 2A-7.
The inductors L1-Ln of the inductor component 18 may be magnetically coupled to one another, may be magnetically uncoupled from one another, or some of the inductors may be magnetically coupled and others of the inductors may be magnetically uncoupled. Power supplies incorporating magnetically coupled inductors, magnetically uncoupled inductors, or both magnetically coupled and magnetically uncoupled inductors, are discussed in the following U.S. Patent Applications, which are incorporated by reference: application Ser. No. 11/903,185 filed Sep. 19, 2007, Ser. Nos. 12/136,014, 12/136,018, 12/136,023 all filed Jun. 9, 2008, and Ser. No. 12/189,112 filed Aug. 8, 2008.
The current sensors 201-20n respectively generate sense signals IFB1-IFBn, which respectively represent the phase currents i1-in. For example, each of the signals IFB1-IFBn may be a respective voltage that has substantially the same signal phase as the corresponding phase current i and that has an amplitude that is substantially proportional to the amplitude of the corresponding phase current.
The controller 22 may be any type of controller suitable for use in a power supply, is supplied by voltages VDDcontroller and VSScontroller, and receives the regulated output voltage Vout, a reference voltage Vref, and the sense signals IFB1-IFBn, which are fed back to the controller from the current sensors 201-20n, respectively. The controller 22 may use Vref and the fed back Vout and IFB1-IFBn to conventionally regulate Vout to a specified value.
The filter capacitor 24 is coupled between the regulated output voltage Vout and a voltage VSScap, and works in concert with the inductors L1-Ln and the optional filter inductor 26 (if present) to maintain the amplitude of the steady-state ripple-voltage component of Vout within a desired range, which may be on the order of hundreds of microvolts (μV) to tens of millivolts (mV). Although only one filter capacitor 24 is shown, the power supply 10 may include multiple filter capacitors coupled in electrical parallel. Furthermore, multiple serially coupled LC filter stages (each stage would be similar to the stage formed by the optional filter inductor 26 and the filter capacitor 24) may be disposed between Vout and the inductors L1-Ln, and the feedback to the controller 22 may be taken from Vout (the output of the last filter stage) or from any one of the previous filter stages. Moreover, VSScap may be equal to VSScontroller and to VL1-VLn; for example, all of these voltages may equal ground.
The optional filter inductor 26 may be omitted from the power supply 10. For example, the filter inductor 26 may be omitted if the inductors L1-Ln are not magnetically coupled to one another, or if the inductors L1-Ln are magnetically coupled to one another and the respective leakage inductances of the inductors L1-Ln are sufficient to perform the specified inductive filtering function. Omitting the filter inductor 26 may reduce the size (e.g., the layout area) and component count of the power supply 10, and may eliminate a component through which the total supply current (i.e., i1+i2+ . . . +in) flows.
The power supply 10 may provide the regulated voltage Vout to a load 28, such as a microprocessor or other electronic load.
Still referring to FIG. 1, alternate embodiments of the power supply 10 are contemplated. For example, although described as a single-phase or multiphase buck converter, the power supply 10 may be any other type of single-phase or multiphase power supply. Furthermore, the current sensors 201-20n may be omitted.
FIGS. 2A-2C are respective side, bottom, and schematic views of an embodiment of a transistor component 30, which includes a low-profile surface-mount package 32 and an NMOS transistor 34 such as one of the transistors 141-14n and 161-16n of FIG. 1. D, S, and G respectively indicate the drain, source, and gate leads of the transistor 34, and, in one embodiment, the package length l, width w, and height h have approximately the following respective values: 6.15 millimeters (mm), 5.15 mm, and 1.1 mm. As discussed below in conjunction with FIGS. 3-7, one or more transistor components like the transistor component 30 may be used to implement the transistors 141-14n and 161-16n in a physical implementation of the power supply 10 of FIG. 1.
Still referring to FIGS. 2A-2C, alternate embodiments of the transistor component 30 are contemplated. For example, although described as including one NMOS transistor 34, the component 30 may include multiple transistors, one or more transistors of different types (e.g., bipolar), or other electronic components such as one or more diodes.
FIG. 3A is a perspective view of a portion 40 of an embodiment of the power supply 10 of FIG. 1, in which the inductor component 18 is stacked over one or more transistor components to reduce the layout area occupied by the power supply.
FIG. 3B is a side view of the portion 40 of FIG. 3A.
Referring to FIGS. 3A and 3B, the power-supply portion 40 includes transistor components 421-42n and 441-44n, the inductor component 18, and a circuit board 46 to which the components 18, 42, and 44 are mounted.
The transistor components 421-42n respectively include the high-side drive transistors 141-14n of FIG. 1, and the transistor components 441-44n respectively include the low-side drive transistors 161-16n of FIG. 1. The transistor components 421-42n and 441-44n may be similar to the transistor component 30 of FIGS. 2A-2C.
The corresponding leads of each high-side/low-side pair of transistor components 42 and 44 are coupled to a respective conductive trace 48 on the circuit board 46, where the conductive trace corresponds to a respective node INT of FIG. 1. For example, the source leads S of the transistor component 421 and the drain leads D of the transistor component 441 are soldered to the trace 481 (corresponds to the node INT1 of FIG. 1), the source leads S of the transistor component 422 and the drain leads D of the transistor component 442 are soldered to the trace 482 (corresponds to the node INT2 of FIG. 1), and so on. Alternatively, because of the direction of the phase currents i1-in when the low-side transistors 161-16n are on, the source leads S of the low-side transistor components 441-44n (instead of the drain leads D of the low-side transistor components) may be soldered to the respective traces 481-48n.
The inductor component 18 includes a package 50, which is shown in phantom dashed line, the inductors L1-Ln, which are disposed inside of the package and which are omitted from FIGS. 3A-3B for clarity, and conductive leads 521-52n and 54.
The package 50 includes an upper surface 56, which faces away from the circuit board 46, and a lower surface 58, which faces toward the circuit board. The package 50 may be formed from plastic, ceramic, or any other suitable material.
Protruding from the lower surface 56 are supports (hereinafter standoffs) 601 and 602, which together with the lower surface, form a recess 62, which receives, at least partially, the transistor components 42 and 44. That is, a depth d of the recess 62 is greater than or equal to the height h of the transistor components 42 and 44 so that the when the inductor component 18 is positioned over the transistor components 42 and 44, the standoffs 601 and 602 contact the circuit board 46, and thus support the inductor component over the transistor components. Therefore, the standoffs 601 and 602 allow one to stack the inductor component 18 and the transistor components 42 and 44.
Each of the leads 521-52n is coupled to the drive node (the node respectively corresponding to the node INT1-INTn of FIG. 1) of a respective inductor L1-Ln, and is soldered to a respective trace 481-48n. The leads 521-52n may also act as standoffs.
In contrast, the lead 54 is coupled to the output nodes of all of the inductors L1-Ln, and is soldered to a circuit-board trace (not shown in FIGS. 3A and 3B) that is connected to the filter inductor 26 if the filter inductor is present or to the node providing Vout if the filter inductor is omitted. Like the leads 521-52n, the lead 54 may also act as a standoff.
In an embodiment of the power-supply portion 40, the height of the inductor component 18 measured at its upper surface 56 may be less than or equal to about 4 mm, which may be low enough for many power-supply applications.
Still referring to FIGS. 3A-3B, alternate embodiments of the power-supply portion 40 and the inductor component 18 are contemplated. For example, although shown as covering only parts of the transistor components 42 and 44, the inductor component 18 may completely cover some or all of the transistor components, or may not cover any portion of some of the transistor components. Furthermore, although shown disposed at the ends of the package 50, the standoffs 601 and 602 may be disposed at other locations (e.g., the center) of the package. Moreover, although two standoffs 601 and 602 are shown, the package 50 may include more or fewer than two standoffs. In addition, the leads 52 and 54 may be disposed at locations of the package other than the illustrated locations. For example, the leads 521-52n may each protrude from the lower surface 58 over a respective one of the traces 481-48n. Furthermore, although the inductor component 18 is described as being stacked over the transistor components 42 and 44, the transistor components may be stacked over the inductor component 18 in a similar manner, or, in general, any first component may be stacked over any second component in a similar manner. Moreover, more than two components may be stacked over one another. In addition, the space between the lower surface 58 of the inductor-component package 50 and the circuit board 46 (and between the lower surface of the package and the transistor components 42 and 44 if d>h) may be partially or completely filled with a material such as epoxy or a thermally conductive material. Furthermore, although discussed as including inductors and transistors, respectively, the components 18, 42, and 44 may also include other circuit elements. Moreover, the dimensions of the inductor component 18 and the transistor components 42 and 44 may be different than disclosed.
FIG. 4 is a side view of another embodiment of the power-supply portion 40 of FIGS. 3A and 3B including another embodiment of the inductor component 18. The inductor component 18 of FIG. 4 includes a package 70 and standoffs 721 and 722, and is similar to the inductor component 18 of FIGS. 3A and 3B except that unlike the standoffs 601 and 602, which are integral with the package 50, the standoffs 721 and 722, are attached to the package 70. For example, the standoff's 721 and 722 may be made of metal and attached the sides of the package 70, or they may be part of and extend from a lead frame (not shown in FIG. 4) internal to the package 70. Alternatively, the standoffs 721 and 722 may be conductive leads that are respectively coupled to the inductors L1-Ln or to other circuit elements within the package 70. For example, the output lead 54 (FIGS. 3A and 3B) may form the standoff 721.
Alternate embodiments of the power-supply portion 40 and the inductor component 18 of FIG. 4 are contemplated. For example, the alternate embodiments discussed above in conjunction with FIGS. 3A and 3B are contemplated for the power-supply portion 40 and inductor component 18 of FIG. 4.
FIG. 5 is a side view of another embodiment of the power-supply portion 40 of FIG. 3A including another embodiment of the inductor component 18. The inductor component 18 of FIG. 5 is similar to the inductor component 18 of FIGS. 3A and 3B except that the component 18 of FIG. 5 also includes a heat sink 80 attached to the upper surface 56 of the package 50 with, e.g., a thermally conductive adhesive. Furthermore, any space 82 between the lower surface 58 of the package 50 and the transistor components 42 and 44 and the circuit board 46 may be filled with a thermally conductive material such that the heat sink 80 is operable not only to dissipate heat generated by the inductors L1-Ln (not shown in FIG. 5), but is also operable to dissipate heat generated by the transistor components and any other components (not shown in FIG. 5) over which the inductor component 18 is disposed. The heat sink 80 may be made from metal or from any other heat-conductive material.
Alternate embodiments of the power-supply portion 40 and the inductor component 18 of FIG. 5 are contemplated. For example, the heat sink 80 may have a different shape or pattern than disclosed in conjunction with FIG. 5. Furthermore, the heat sink 80 may be attached to the package 50 in any conventional manner other than with an adhesive, and may be attached to the sides of the package in addition to or instead of to the upper surface 56. Moreover, a thermoelectric cooler (i.e., a Peltier device) may be disposed between the heat sink 80 and the package 50 (hot side of the thermo-electric cooler toward the heat sink, cool side toward the package) such that that combination of the heat sink and cooler may dissipate more heat from the inductor component 18 than the heat sink alone. In addition, the heat sink 80 may be attached to the upper surface 56 of the package 70 of FIG. 4 to form another embodiment of the inductor component 18. Furthermore, the alternate embodiments discussed above in conjunction with FIGS. 3A, 3B, and 4 for the power-supply portion 40 and the inductor component 18 are also contemplated for the power-supply portion 40 and the inductor component 18 of FIG. 5.
FIG. 6 is a side view of another embodiment of the power-supply portion 40 of FIG. 3A including another embodiment of the inductor component 18. The inductor component 18 of FIG. 6 is similar to the inductor component 18 of FIGS. 3A and 3B except that the inductor component of FIG. 6 includes a package 90 having an upper surface 92 that is patterned to have an increased area (as compared to the area of the lower surface 58) for the increased dissipation of heat. That is, the package 90 acts as a heat sink. Furthermore, any space 82 between the lower surface 58 of the package 90 and the transistor components 42 and 44 and the circuit board 46 may be filled with a thermally conductive material such that the package 90 is operable not only to dissipate heat generated by the inductors L1-Ln (not shown in FIG. 6), but is also operable to dissipate heat generated by the transistor components. The package 90 may be made from plastic or from any other suitable heat-conductive material.
Alternate embodiments of the power-supply portion 40 and the inductor component 18 of FIG. 6 are contemplated. For example, the upper surface 92 of the package 90 may have a different pattern or shape than that disclosed in conjunction with FIG. 6. Furthermore, the sides of the package 90 may also be patterned to increase their surface areas. Moreover, the upper surface 56 of the package 70 of FIG. 4 may be patterned to increase the area of the surface 56 and improve the heat dissipation rate of the package, and to thus form another embodiment of the inductor component 18. In addition, the alternate embodiments discussed above in conjunction with FIGS. 3A, 3B, 4, and 5 for the power-supply portion 40 and for the inductor component 18 are also contemplated for the power-supply portion 40 and the inductor component 18 of FIG. 6.
FIG. 7 is a perspective view of a portion 100 of an embodiment of the power supply 10 of FIG. 1, in which another embodiment of the inductor component 18 spans only a single pair of transistor components 42 and 44. For brevity, only the transistor components 42 and 44 and inductor component 18 of a single power-supply phase are shown, it being understood that for the power supply 10 having multiple phases, the layouts of the other inductor components relative to the other high-side/low-side transistor-component pairs may be similar.
The inductor component 18 includes a package 102 having upper and lower surfaces 56 and 58, and standoffs 1041 and 1042, which are similar to the standoffs 721 and 722 of FIG. 4. In one embodiment, the standoff 1041 also forms an output lead that is coupled between an output node of the inductor L (not shown in FIG. 7) within the package 102 and Vout (or the filter inductor 26 if present), and the standoff 1042 also forms an input lead that is coupled between an input node of the inductor L and the source of the transistor 141 (not shown in FIG. 7) in the transistor component 42 and the drain of the transistor 161 (not shown in FIG. 7) in the transistor component 44. The conductive traces on the circuit board 46 to which the standoffs/leads 1041 and 1042 are respectively soldered are omitted from FIG. 7 for clarity.
Alternate embodiments of the power-supply portion 100 and the inductor component 18 of FIG. 7 are contemplated. For example, the standoffs 1041 and 1042 may be replaced with standoffs similar to the standoffs 601 and 602 of FIG. 3A, and the inductor leads may extend from the standoffs or from other portion of the package 102. In addition, the alternate embodiments discussed above in conjunction with FIGS. 3A, 3B, 4, 5, and 6 for the power-supply portion 40 and for the inductor component 18 are also contemplated for the power-supply component 100 and the inductor component 18 of FIG. 7.
FIG. 8 is a block diagram of a system 110 (here a computer system), which may incorporate a single-phase or multiphase power supply 112 (such as the power supply 10 of FIG. 1) that includes one or more of the embodiments of the power-supply portion 40 or of the inductor component 18 of FIGS. 3A-7.
The system 110 includes computer circuitry 114 for performing computer functions, such as executing software to perform desired calculations and tasks. The circuitry 114 typically includes a controller, processor, or one or more other integrated circuits (ICs) 116, and the power supply 112, which provides power to the IC(s) 116. One or more input devices 118, such as a keyboard or a mouse, are coupled to the computer circuitry 114 and allow an operator (not shown) to manually input data thereto. One or more output devices 120 are coupled to the computer circuitry 114 to provide to the operator data generated by the computer circuitry. Examples of such output devices 120 include a printer and a video display unit. One or more data-storage devices 122 are coupled to the computer circuitry 114 to store data on or retrieve data from external storage media (not shown). Examples of the storage devices 122 and the corresponding storage media include drives that accept hard and floppy disks, tape cassettes, compact disk read-only memories (CD-ROMs), and digital-versatile disks (DVDs).
From the foregoing it will be appreciated that, although specific embodiments have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the description. Furthermore, where an alternative is disclosed for a particular embodiment, this alternative may also apply to other embodiments even if not specifically stated.

## Claims

1. A component, comprising:
a package including a circuit element disposed within the package and the package further including a first surface and a first standoff protruding from the first surface, the package being configured to be positioned over external electronic components and operable to dissipate heat from the circuit element and from the external electronic components;
wherein the package further includes a second surface disposed opposite to the first surface and a heat sink protruding from the second surface, the heat sink integral with the package; and
wherein the first surface has a first area and the second surface has a second area that is greater than the first area.

2. The component of claim 1 wherein:
the first surface has a perimeter; and
the first standoff protrudes from the surface near the perimeter.

3. The component of claim 1 wherein the first standoff is integral with the package.

4. The component of claim 1 wherein:
the first standoff comprises a conductive lead; and
the circuit element comprises a node coupled to the conductive lead.

5. The component of claim 1 wherein the package includes a second standoff protruding from the first surface and spaced from the first standoff.

6. The component of claim 1 wherein the circuit element comprises an inductor.

7. The component of claim 1, further comprising:
wherein the circuit element comprises a first inductor; and
a second inductor disposed within the package and magnetically uncoupled from the first inductor.

8. The component of claim 1, further comprising:
wherein the circuit element comprises a first inductor; and
a second inductor disposed within the package and magnetically coupled to the first inductor.

9. The component of claim 1,
wherein the external electronic components are positioned in contact with the first surface.

10. The component of claim 9, wherein the second surface of the package is patterned to increase the second area relative to the first area of the first surface when the first surface is planar.

11. The component of claim 1,
wherein there is space between the first surface and the external electronic components; and
wherein the space is at least partially filled with a thermally conductive material.

12. The component of claim 11, wherein the second area of the package is patterned to increase the second area of the second surface relative to the first area of the first surface.

13. The component of claim 12 wherein the package further includes side surfaces and wherein the side surfaces of the package are patterned to increase the areas of the side surfaces relative to planar side surfaces.

14. The component of claim 11, wherein the thermally conductive material comprises epoxy.

15. A component, comprising:
a package having an integral circuit element disposed within the package and the package including at least one standoff, the package further including,
a first surface,
a second surface opposite the first surface, the second surface including at least one recess adapted to receive at least one external active electronic component, and

wherein the package is configured with the first surface having an patterned non-planar area that is greater than a planar second area of the second surface to dissipate heat from the circuit element and from each external electronic component.

16. The component of claim 15 wherein each recess has a depth and wherein each external electronic component has a height that is less than the depth.

17. The component of claim 16 further comprising thermally conductive material disposed each recess and each external electronic component disposed within that recess.

18. The component of claim 15 wherein each recess has a depth and wherein each external electronic component has a height that is approximately equal to the depth.