CONTROLLED ON-TIME BUCK PFC

• US 20100123448A1
• Filed: 11/18/2008
• Published: 05/20/2010
• Est. Priority Date: 11/18/2008
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Lu, Bing, Neidorff, Robert A.
• Granted Patent: US 8,922,189 B2
• Time in Patent Office: Days
• US Class Current: 323/299
• CPC Class Codes: G05F 1/70 Regulating power factor; Regulating reactive current or power
• CPC Class Codes: H02M 1/42 Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
• CPC Class Codes: H02M 1/4291 by using a Buck converter to switch the input current
• CPC Class Codes: H02M 3/157 with digital control
• 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

An apparatus for generating an output voltage from an input voltage is provided. The apparatus comprises a switch that receives the input voltage, an inductor that is coupled to the switch, a capacitor coupled to the inductor with the output voltage being output from a node between the inductor and the capacitor, a measuring circuit that receives and measures the input voltage, and a controller that is coupled to the switch and to the measuring circuit. Additionally, the controller receives the measured input voltage and calculates an on-time for the switch based on the measured input voltage and actuates the switch for the on-time.

Claims

1. An apparatus for generating an output voltage from an input voltage, the apparatus comprising:

a switch that receives the input voltage;

an inductor that is coupled to the switch;

a capacitor coupled to the inductor, wherein the output voltage is output from a node between the inductor and the capacitor;

a measuring circuit that receives and measures the input voltage; and

a controller that is coupled to the switch and to the measuring circuit, wherein the controller receives the measured input voltage and calculates an on-time for the switch based on the measured input voltage, and wherein the controller actuates the switch for the on-time.

2. The apparatus of claim 1, wherein the on-time is proportional to the square of the input voltage divided by the difference between the input voltage and the output voltage.

3. The apparatus of claim 1, wherein the on-time is proportional to the input voltage.

4. The apparatus of claim 1, wherein the apparatus further comprises a second switch that is coupled between the first switch and ground, wherein the controller is adapted to actuate the second switch.

5. The apparatus of claim 4, wherein the first and second switches are NMOS FETs.

6. The apparatus of claim 1, wherein a reverse bias diode is coupled between the switch and ground.

7. An apparatus for generating an output voltage from an input voltage, the apparatus comprising:

a bridge that receives the input voltage;

an inductor that is coupled to the bridge;

a capacitor coupled to the inductor, wherein the output voltage is output from a node between the inductor and the capacitor;

a measuring circuit that receives and measures the input voltage; and

a controller that is coupled to the bridge and to the measuring circuit, wherein the controller receives the measured input voltage and calculates an on-time, and wherein the on-time is a function of the measured input voltage, and wherein the controller actuates the bridge for the on-time.

8. The apparatus of claim 7, wherein the on-time is proportional to the square of the input voltage divided by the difference between the input voltage and the output voltage.

9. The apparatus of claim 7, wherein the on-time is proportional to the input voltage.

10. The apparatus of claim 7, wherein the bridge further comprises:

a first FET that receives the input voltage at its drain, that is adapted to receive a first actuation signal at its gate from the controller, and that is coupled to the inductor at its source; and

a second FET that is coupled to the source of the first FET at its drain, that is adapted to receive a second actuation signal at its gate, and that is coupled to ground at its source.

11. The apparatus of claim 10, wherein the first and second FETs are NMOS FETs.

12. The apparatus of claim 7, wherein the bridge further comprises

a FET that receives the input voltage at its drain, that is adapted to receive a first actuation signal at its gate from the controller, and that is coupled to the inductor at its source;

and

a reverse bias diode coupled between the source of the FET and ground.

13. The apparatus of claim 12, wherein the FET is an NMOS FET.

15. The method of claim 11, wherein the on-time is proportional to the square of the input voltage divided by the difference between the input voltage and the output voltage.

14. A method for generating an output voltage from an input voltage, the method comprising:

receiving the input voltage by a switch and by a measuring circuit;

measuring the input voltage with the measuring circuit;

calculating an on-time for the switch, wherein the on-time is a function of the measured input voltage;

actuating the switch for the on-time; and

supplying an input current and the input voltage to an inductor.

16. The method of claim 14, wherein the on-time is proportional to the input voltage.

17. The method of claim 14, wherein the method further comprises actuating a second switch that is coupled to the inductor.