Voltage converter

• US 20030067286A1
• Filed: 10/15/2002
• Published: 04/10/2003
• Est. Priority Date: 04/13/2000
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Tihanyi, Jenoe
• Granted Patent: US 6,639,388 B2
• Time in Patent Office: Days
• US Class Current: 323/224
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load

Abstract

A voltage transformer includes a pair of input terminals for applying an input voltage, a series circuit connected in parallel to the pair of input terminals of a first switch, and a low pass filter. The low pass filter has output terminals for connecting a load. A freewheeling circuit is connected in parallel to the low pass filter. The freewheeling circuit has a second switch, which is configured as a MOS transistor, with a gate terminal and a load path formed between a first load path terminal and a second load path terminal. The MOS transistor has a body zone mounted in a floated manner or connected to a source zone by an ohmic resistor.

Claims

1. A voltage converter, comprising:

a pair of input terminals for receiving an input voltage;

a series circuit connected in parallel with said pair of input terminals and having;

a first switch; and

a low-pass filter having output terminals to be connected to a load;

a freewheeling circuit connected in parallel with said low-pass filter, said freewheeling circuit having a second switch, said second switch having;

a first load path terminal;

a second load path terminal;

a load path formed between said second load path terminal and said first load path terminal; and

a control terminal; and

said second switch being a MOS transistor having one of;

a floating body zone; and

a source zone, a non-reactive resistor, and a body zone connected to said source zone through said non-reactive resistor.

2. The voltage converter according to claim 1, including a rectifier element connected between said first load path terminal and said control terminal of said second switch.

3. The voltage converter according to claim 1, wherein said floating body zone is a body zone not connected to a defined potential.

4. The voltage converter according to claim 1, including a Schottky diode connected in parallel with said load path of said second switch.

5. The voltage converter according to claim 1, wherein:

said low-pass filter has a series circuit with;

a coil; and

a capacitor; and

said capacitor is connected in parallel with said output terminals.

6. The voltage converter according to claim 1, wherein said first switch is a transistor.

7. The voltage converter according to claim 1, wherein said first switch is a field-effect transistor.

8. The voltage converter according to claim 1, including a drive circuit having an output terminal connected to said first switch for driving said first switch.

9. The voltage converter according to claim 8, wherein said drive circuit drives said first switch dependent upon one of:

an output voltage tapped off at said output terminals; and

a current through said coil of said low-pass filter.

10. The voltage converter according to claim 1, including a drive circuit connected to said control terminal of said second switch and driving said second switch dependent upon a switching state of said first switch.

11. The voltage converter according to claim 1, including a drive circuit for both of said first and second switches.

12. The voltage converter according to claim 11, wherein said drive circuit prevents said first switch and said second switch from both being in an on state simultaneously.

13. The voltage converter according to claim 1, including a drive circuit connected to said first switch and said second switch.

14. The voltage converter according to claim 13, wherein said drive circuit prevents said first switch and said second switch from both being in an on state simultaneously.

15. The voltage converter according to claim 1, wherein said second switch is a MOSFET having:

a body zone; and

a recombination zone formed in said body zone.