DC-DC converter assembly with an output inductor accommodating a power stage attached to a circuit board

• US 9,711,279 B2
• Filed: 10/28/2013
• Issued: 07/18/2017
• Est. Priority Date: 10/28/2013
• Status: Active Grant

• Current Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Original Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Inventors: Todorov, Emil, Molloy, Brian
• Primary Examiner(s): Nguyen, Tuyen
• Application Number:
  US14/065,021
• Publication Number:
  US 20150116972A1
• Time in Patent Office: 1,359 Days
• Field of Search: 336 65, 336 83, 336192, 336200, 336232
• CPC Class Codes: H01F 17/06 with core substantially closed in itself, e.g. toroid
• CPC Class Codes: H01F 27/2847 Sheets; Strips H01F27/2866 takes precedence
• CPC Class Codes: H01F 27/292 Surface mounted devices
• CPC Class Codes: H01F 41/0246 Manufacturing of magnetic circuits by moulding or by pressing powder magnetic cores made by moulding or by pressing powder H01F27/255; soft magnetic particles H01F1/20, H01F1/36
• CPC Class Codes: H01F 5/00 Coils superconducting coils H01F6/06; fixed inductances of the signal type H01F17/00
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H02M 3/003 Constructional details, e.g. physical layout, assembly, wiring or busbar connections
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H05K 1/18 Printed circuits structurally associated with non-printed electric components H05K1/0201, H05K1/023, H05K1/0243, and H05K1/16 take precedence
• CPC Class Codes: Y10T 29/49075 including permanent magnet or core
• CPC Class Codes: Y10T 29/49128 Assembling formed circuit to base

Abstract

A DC-DC converter assembly includes a board having a first side and a second side opposite the first side, a power stage die of a DC-DC converter attached to the first side of the board, and an output inductor electrically connected to an output of the power stage die and disposed over the power stage die on the first side of the board. The output inductor includes a magnetic core and an electrical conductor having first and second terminals attached to the first side of the board. The output inductor accommodates the power stage die under the magnetic core so that the power stage die is interposed between the magnetic core and the board. A corresponding method of manufacturing the DC-DC converter assembly and method of manufacturing the output inductor are also disclosed.

Claims

1. A DC-DC converter assembly, comprising:

a board having a first side and a second side opposite the first side;

a power stage die of a DC-DC converter attached to the first side of the board;

an output inductor electrically connected to an output of the power stage die and disposed over the power stage die on the first side of the board, the output inductor comprising a magnetic core and an electrical conductor having first and second terminals attached to the first side of the board, the output inductor accommodating the power stage die under the magnetic core so that the power stage die is interposed between the magnetic core and the board;

a load attached to the first side of the board;

a plurality of input capacitors electrically connected to input terminals of the power stage die, the input capacitors that provide a shortest current commutation loop for the power stage die being attached to the first side of the board and the other input capacitors being attached to the second side of the board;

an output capacitor electrically connected between the output inductor and the load, and attached to the second side of the board; and

a plurality of decoupling capacitors electrically connected to power terminals of the power stage die, and attached to the second side of the board,

wherein a total footprint of the power stage die, the output inductor, the plurality of input capacitors, the output capacitor and the plurality of decoupling capacitors is at least a third of the combined surface area of the power stage die, the output inductor, the plurality of input capacitors, the output capacitor and the plurality of decoupling capacitors.

2. The DC-DC converter assembly of claim 1, wherein the magnetic core is spaced apart from the power stage die.

3. The DC-DC converter assembly of claim 1, wherein the magnetic core has a thinner inner region and a thicker outer region so that a gap exists between the thinner inner region and the first side of the board, and wherein the gap accommodates a thickness of the power stage die.

4. The DC-DC converter assembly of claim 3, wherein the thickness of the power stage die and the gap between the thinner inner region and the first side of the board are both less than 1 mm.

5. The DC-DC converter assembly of claim 1, wherein the magnetic core has a planar side facing the first side of the board, and wherein the first and second terminals of the output inductor extend from a periphery of the magnetic core beyond the planar side by a distance corresponding to at least a thickness of the power stage die to realize a gap between the planar side of the magnetic core and the board that accommodates the power stage die.

6. The DC-DC converter assembly of claim 1, wherein the first and second terminals of the magnetic core are attached to the first side of the board by first and second blocks at a periphery of the magnetic core, and wherein the first and second blocks each have a thickness corresponding to at least a thickness of the power stage die to realize a gap between the magnetic core and the board that accommodates the power stage die.

7. The DC-DC converter assembly of claim 1, wherein the DC-DC converter is a multi-phase converter and the power stage die provides one phase of the multi-phase converter.

8. The DC-DC converter assembly of claim 1, wherein the power stage die dissipates less than 2 W at a thermal design current of the DC-DC converter.

9. The DC-DC converter assembly of claim 1, wherein the output inductor accommodates the input capacitors attached to the first side of the board under the magnetic core so that the power stage die and the input capacitors attached to the first side of the board are interposed between the magnetic core and the board after attachment to the first side of the board.

10. The DC-DC converter assembly of claim 1, wherein at least some of the capacitors attached to the second side of the board are disposed at least partly within the footprint of the output inductor attached to the first side of the board.

11. The DC-DC converter assembly of claim 1, wherein the electrical conductor is shaped like a staple and the terminals are spaced apart at opposing sides of the magnetic core so that power stage die fits between the terminals.

12. The DC-DC converter assembly of claim 1, wherein the output inductor completely covers the power stage die.

20. The DC-DC converter assembly of claim 1, wherein the total footprint of the power stage die, the output inductor, the plurality of input capacitors, the output capacitor and the plurality of decoupling capacitors is at least half the combined surface area of the power stage die, the output inductor, the plurality of input capacitors, the output capacitor and the plurality of decoupling capacitors.

13. A method of manufacturing a DC-DC converter assembly, the method comprising:

attaching a power stage die of a DC-DC converter to a first side of a board, the board further having a second side opposite the first side;

positioning an output inductor over the power stage die on the first side of the board, the output inductor comprising a magnetic core and an electrical conductor having first and second terminals, the output inductor accommodating the power stage die under the magnetic core so that the power stage die is interposed between the magnetic core and the board;

attaching the first and second terminals of the output inductor to the first side of the board so that the output inductor is electrically connected to an output of the power stage die;

attaching a load to the first side of the board;

attaching input capacitors that provide a shortest current commutation loop for the power stage die to the first side of the board, the input capacitors being electrically connected to input terminals of the power stage die;

attaching additional input capacitors to the second side of the board, the additional input capacitors being electrically connected to the input terminals of the power stage die;

attaching an output capacitor to the second side of the board, the output capacitor being electrically connected between the output inductor and the load; and

attaching a plurality of decoupling capacitors to the second side of the board, the decoupling capacitors being electrically connected to power terminals of the power stage die,

wherein a total footprint of the power stage die, the output inductor, the plurality of input capacitors, the output capacitor and the plurality of decoupling capacitors is at least a third of the combined surface area of the power stage die, the output inductor, the plurality of input capacitors, the output capacitor and the plurality of decoupling capacitors.

14. The method of claim 13, wherein the magnetic core has a thinner inner region and a thicker outer region so that a gap exists between the thinner inner region and the first side of the board, and wherein the gap accommodates a thickness of the power stage die.

15. The method of claim 13, wherein the magnetic core has a planar side facing the first side of the board, and wherein the first and second terminals of the output inductor extend from a periphery of the magnetic core beyond the planar side by a distance corresponding to at least a thickness of the power stage die to realize a gap between the planar side of the magnetic core and the board that accommodates the power stage die.

16. The method of claim 13, comprising attaching the first and second terminals of the output inductor to the first side of the board by first and second blocks at a periphery of the magnetic core, and the first and second blocks each having a thickness corresponding to at least a thickness of the power stage die to realize a gap between the magnetic core and the board that accommodates the power stage die.

17. The method of claim 13, wherein the DC-DC converter is a multi-phase converter and the power stage die provides one phase of the multi-phase converter.

18. The method of claim 13, wherein the power stage die dissipates less than 2 W at a thermal design current of the DC-DC converter.

19. The method of claim 13, wherein the output inductor accommodates the input capacitors attached to the first side of the board under the magnetic core so that the power stage die and the input capacitors attached to the first side of the board are interposed between the magnetic core and the board after attachment to the first side of the board.

21. The method of claim 13, wherein the total footprint of the power stage die, the output inductor, the plurality of input capacitors, the output capacitor and the plurality of decoupling capacitors is at least half the combined surface area of the power stage die, the output inductor, the plurality of input capacitors, the output capacitor and the plurality of decoupling capacitors.