Dual-output direct current voltage converter

• US 6,756,772 B2
• Filed: 07/08/2002
• Issued: 06/29/2004
• Est. Priority Date: 07/08/2002
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Cogency Semiconductor, Inc. (Nova Bancorp Group Ltd.)
• Inventors: McGinnis, Donald Mike
• Primary Examiner(s): STERRETT, JEFFREY L
• Application Number:
  US10/189,548
• Publication Number:
  US 20040004465A1
• Time in Patent Office: 722 Days
• Field of Search: 323/225, 323/267, 323/271, 323/282, 323/350, 363/60
• US Class Current: 323/225
• CPC Class Codes: H02M 1/009 having two or more independently controlled outputs for DC-DC converter with intermediate AC H02M3/33561
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps
• CPC Class Codes: H02M 3/1588 comprising at least one synchronous rectifier element H02M3/1582, H02M3/1584 take precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A step-down switching voltage regulator with a push-pull output stage is adapted to provide a voltage converter with an auxiliary voltage rail that supplies an auxiliary voltage that is higher than the input supply voltage. The push-pull output stage of the step-down voltage regulator is used to drive a charge pump voltage-doubler circuit. In this way, a single integrated topology provides a regulated low voltage output as well as an auxiliary high voltage output. The circuit topology enables a low component count resulting in lower component cost and smaller physical size.

Claims

1. A dual-output direct current (DC) voltage converter for converting an input DC voltage to at least two different output DC voltages, comprising:

an input terminal for receiving the input DC voltage from a power voltage source;

a step-down voltage regulator circuit connected to the input terminal for providing a regulated output DC voltage lower than the input DC voltage; and

a charge pump circuit connected to the input terminal and coupled to the step-down voltage regulator circuit, for providing an auxiliary output DC voltage higher than the input DC voltage;

wherein the step-down voltage regulator circuit includes first and second switches coupled in series between the input terminal and a ground potential, and an output filter connected at a junction between the first and second switches; and

the charge pump circuit is further coupled to the step-down voltage regulator circuit at the junction between the first and second switches of the step-down voltage regulator circuit.

2. A dual-output voltage converter as claimed in claim 1 wherein the first and second switches comprise first and second bipolar transistors.

3. A dual-output voltage converter as claimed in claim 1 further comprising control circuitry for preventing the first and second switches from simultaneously being on.

4. A dual-output voltage converter as claimed in claim 3 wherein the output filter comprises an inductor connected in series with a storage capacitor.

5. A dual-output voltage converter as claimed in claim 4 wherein a junction between the inductor and storage capacitor provides the regulated output DC voltage lower than said input DC voltage.

6. A dual-output voltage converter as claimed in claim 5 wherein the regulated output DC voltage provided at the junction between the inductor and storage capacitor is fed back to the controller to maintain the regulated output DC voltage at a predetermined level.

7. A dual-output voltage converter as claimed in claim 1 wherein the first and second switches comprise first and second field effect transistors.

8. A dual-output voltage converter as claimed in claim 1 wherein the charge pump circuit comprises a first stage having a first diode coupled to a first capacitor wherein an anode of the first diode is coupled to the input terminal, a cathode of the first diode is coupled to a first electrode of the first capacitor and a second electrode of the first capacitor is coupled to the junction between the first and second switches.

9. A dual-output voltage converter as claimed in claim 8 wherein the first and second field effect transistors are metal oxide semiconductor field effect transistors (MOSFETs).

10. A dual-output voltage converter as claimed in claim 8 wherein the charge pump circuit further comprises a second stage having a second diode coupled to a second capacitor wherein an anode of the second diode is coupled to a junction between the first diode and the first capacitor, a cathode of the second diode is coupled to a first electrode of the second capacitor, and a second electrode of the second capacitor is coupled to a ground potential.

11. A dual-output voltage converter as claimed in claim 10 wherein the first and second switches of the step-down voltage regulator circuit further control the first and second capacitors of the charge pump circuit so that the first capacitor is charged by the input voltage and the second capacitor is charged by a discharge of the first capacitor.

12. A dual-output voltage converter as claimed in claim 10 wherein a junction between the second diode and second capacitor provides the auxiliary output DC voltage higher than said input DC voltage.

13. A dual-output DC voltage converter for converting an input DC voltage to at least two different DC output voltages, comprising:

an input terminal for receiving the input DC voltage from a power voltage source;

a step-down voltage regulator circuit that includes controlled switches connected in series between the input terminal and a ground potential;

an output filter connected between a low-voltage output terminal and a junction between the switches; and

a multi-stage charge pump circuit connected to the input terminal and coupled to the junction between the switches, for providing an auxiliary output DC voltage higher than the input DC voltage.

14. A dual-output voltage converter as claimed in claim 13 wherein the multi-stage charge circuit comprises a first stage having a first diode with a cathode coupled to a first electrode of a first capacitor and an anode coupled to the input terminal, a second electrode of the first capacitor being coupled to the junction between the switches.

15. A dual-output voltage converter as claimed in claim 14 wherein the multi-stage charge circuit further comprises a second stage having a second diode with an anode coupled to a junction between the first diode and the first capacitor and a cathode connected to a first electrode of a second capacitor.

16. A dual-output voltage converter as claimed in claim 15 wherein a junction between the cathode of the second diode and the first electrode of the second capacitor is connected to an auxiliary output terminal of the dual output voltage converter, and a second electrode of the second capacitor is connected to a ground potential.