Step-down voltage converter

• US 7,940,533 B2
• Filed: 07/26/2005
• Issued: 05/10/2011
• Est. Priority Date: 07/26/2005
• Status: Active Grant

• Current Assignee: Micro Motion Incorporated (Emerson Electric Company)
• Original Assignee: Micro Motion Incorporated (Emerson Electric Company)
• Inventors: Lindemann, Stig, Mansfield, William M.
• Primary Examiner(s): Patel; Rajnikant B
• Application Number:
  US11/994,387
• Publication Number:
  US 20100128499A1
• Time in Patent Office: 2,114 Days
• Field of Search: 363 16- 20, 363/37, 363/49, 363/89, 363/91, 363/71, 363/62, 323/222, 323/224, 323282-288, 323/271, 219/209, 219/497, 219/203
• US Class Current: 363/21.01
• CPC Class Codes: H02M 3/155 using semiconductor devices only

Abstract

A step-down voltage converter (100) for generating an output voltage (VOUT) from an input voltage (VIN) is provided. The converter (100) includes a switch (111) having a first terminal (112) and a second terminal (114), wherein the second terminal (114) is electrically coupled with the output voltage (VOUT). Also included is a rectifier (117) having a first terminal (118) and a second terminal (120), wherein the second terminal (120) is electrically coupled with the output voltage (VOUT). A first inductor (124) electrically couples the first terminal (112) of the switch (111) with the input voltage (VIN). A second inductor (126) magnetically coupled with the first inductor (124) electrically couples the first terminal (118) of the rectifier (117) with a voltage reference (128). A switch controller (110) coupled with the output voltage (VOUT) is configured to control the switch (111).

Claims

1. A step-down voltage converter (100) for generating a direct-current (DC) output voltage (V_OUT) from a direct-current (DC) input voltage (V_IN), comprising:

a field-effect transistor (FET) (Q₁) switch (111) comprising a drain terminal (112) and a source terminal (114), wherein the source terminal (114) of the switch (111) is electrically coupled with the output voltage (V_OUT);

a diode (117) comprising an anode (118) and a cathode (120), wherein the cathode (120) of the diode (117) is electrically coupled with the output voltage (V_OUT);

a first inductor (124) electrically coupling the drain terminal (112) of the switch (111) with the input voltage (V_IN);

a second inductor (126) magnetically coupled with the first inductor (124), the second inductor (126) electrically coupling the anode (118) of the diode (117) with a voltage reference (128); and

a switching controller (110) coupled with the output voltage (V_OUT) and configured to control the switch (111) by way of a gate terminal (216) of the FET (Q₁).

2. The step-down voltage converter (100) of claim 1, wherein the first inductor (124) and the second inductor (126) each comprise an inductance of 1.7 millihenries.

3. The step-down voltage converter (100) of claim 1, further comprising:

a first capacitor (C₁) electrically coupling the input voltage (V_IN) with the voltage reference (128); and

a second capacitor (C₂) electrically coupling the output voltage with the voltage reference (128).

4. The step-down voltage converter (100) of claim 3, wherein the first capacitor (C₁) comprises a capacitance of 22 microfarads.

5. The step-down voltage converter (100) of claim 3, wherein the second capacitor (C₂) comprises a capacitance of 120 microfarads.

6. The step-down voltage converter (100) of claim 1, wherein the voltage reference (128) is ground.

7. The step-down voltage converter (100) of claim 1, wherein a number of turns of the first inductor (124) and a number of turns of the second inductor (126) comprise a ratio of 1:

1.

8. The step-down voltage converter (100) of claim 1, wherein the first inductor (124) comprises a first winding of a transformer, wherein the second inductor (126) comprises a second winding of the transformer, and wherein the first inductor (124) and the second inductor (126) are wound about a core (222).

9. The step-down voltage converter (100) of claim 8, wherein the core (222) is a ferrite core.

10. The step-down voltage converter (100) of claim 1, wherein:

the input voltage (V_IN) and the output voltage (V_OUT) are negative DC voltages; and

the switch (111) comprises a p-channel field-effect transistor (FET)(Q₂).

11. The step-down voltage converter (100) of claim 1, wherein the switch controller (110) is configured to control the switch (111) by turning the switch (111) on and off substantially periodically.

12. The step-down voltage converter (100) of claim 1, wherein the switch controller (110) is configured to control the switch (111) based on the output voltage (V_OUT)

13. An item of industrial instrumentation comprising the step-down voltage converter (100) of claim 1.

14. A Coriolis flowmeter comprising the step-down voltage converter (100) of claim 1.