Monolithic AC/DC converter for generating DC supply voltage

• US 20110080761A1
• Filed: 10/06/2009
• Published: 04/07/2011
• Est. Priority Date: 10/06/2009
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Kung, David
• Granted Patent: US 8,634,218 B2
• Time in Patent Office: Days
• US Class Current: 363/127
• CPC Class Codes: H02M 7/217 using semiconductor devices only
• CPC Class Codes: H02M 7/2176 comprising a passive stage to generate a rectified sinusoidal voltage and a controlled switching element in series between such stage and the output
• CPC Class Codes: H02M 7/219 in a bridge configuration
• CPC Class Codes: H02M 7/2195 the switches being synchronously commutated at the same frequency of the AC input voltage

Abstract

An integrated circuit (IC) comprises a rectifier/regulator circuit coupled to receive an ac source voltage and output a regulated dc voltage. The rectifier/regulator circuit includes first and second switching elements that provide charging current when enabled. The first and second switching elements do not provide charging current when disabled. A sensor circuit is coupled to sense the regulated dc voltage and generate a feedback control signal coupled to the rectifier/regulator circuit that enables the first and second switching elements when the regulated dc voltage is above a target voltage, and disables the first and second switching elements when the regulated dc voltage is below the target voltage.

Claims

1. An integrated circuit (IC) comprising:

a rectifier/regulator circuit coupled to receive an ac source voltage and output a regulated dc voltage, the rectifier/regulator circuit including first and second switching elements that selectively provide charging current when enabled; and

a sensor circuit coupled to sense the regulated dc voltage and generate a feedback control signal coupled to the rectifier/regulator circuit that enables the first and second switching elements when the regulated dc voltage is above a target voltage, and disables the first and second switching elements when the regulated dc voltage is below the target voltage.

2. The IC of claim 1 wherein the IC is a monolithic power IC.

3. The IC of claim 1 wherein the first and second switching elements are respectively coupled to first and second terminals, the first and second terminals being coupled to receive the ac source voltage.

4. The IC of claim 3 wherein the first switching element is conducting when a potential difference between the first and second terminals is positive and first switching element is enabled, the first switching element not conducting when a potential difference between the first and second terminals is negative and first switching element is enabled, the second switching element conducting when a potential difference between the first and second terminals is negative and second switching element is enabled, the second switching element not conducting when a potential difference between the first and second terminals is positive and second switching element is enabled.

5. The IC of claim 4 wherein the sensor circuit includes a supply capacitor coupled to the rectifier/regulator circuit, the regulated dc voltage being generated across the supply capacitor.

6. The IC of claim 5 wherein the sensor circuit further includes a feedback circuit that regulates charging of supply capacitor to maintain a regulated output voltage.

7. An integrated circuit (IC) for generating a regulated dc voltage at a supply node from an ac input voltage comprising:

a rectifier/regulator circuit coupled to receive the ac input voltage across first and second input terminals, the rectifier/regulator circuit including;

a first switching element which includes a first transistor coupled between the first input terminal and the supply node;

a second switching element which includes a second transistor coupled between the second input terminal and the supply node; and

a sensor circuit coupled between the supply node and a ground node, the sensor circuit being operable to sense the regulated dc voltage at the supply node and generate a feedback signal therefrom, the feedback signal being coupled to control the first and second switching elements;

wherein the feedback signal disabling the first and second switching elements from providing charging current to the supply node when the regulated dc voltage is above a target voltage, and enabling the first and second switching elements to provide charging current to the supply node when the regulated dc voltage is below the target voltage.

8. The IC of claim 7 wherein the rectifier/regulator circuit further includes first and second substrate diodes each having an anode coupled to the ground node, a cathode of the first diode being coupled to the first input terminal and a cathode of the second diode being coupled to the second input terminal, the charging current alternately flowing through the first and second substrate diodes when the first and second transistors are enabled.

9. The IC of claim 7 wherein the first switching element further includes a junction field-effect transistor (JFET) coupled between the first input terminal and a drain of the first transistor, the second switching element further including a second JFET coupled between the second input terminal and a drain of the second transistor.

10. The IC of claim 7 wherein the sensor circuit further includes a supply capacitor coupled between the supply node and the ground node.

11. The IC of claim 7 wherein the sensor circuit further includes:

a voltage divider coupled between the supply node and the ground node, the voltage divider generating a feedback input voltage from the regulated dc voltage; and

a comparator that generates the feedback signal by comparing the feedback input voltage to a reference voltage.

12. The IC of claim 7 wherein the anode of the first and second substrate diodes comprises a P-type substrate of the power IC, the cathode of the first diode comprising a N-type well region of the first transistor, the cathode of the second diode comprising a N-type well region of the second transistor.

13. An integrated circuit (IC) for generating a regulated dc voltage at a supply node from an ac input voltage comprising:

a rectifier/regulator circuit coupled to receive the ac input voltage across first and second input terminals, the rectifier/regulator circuit including;

a first switching element which includes a first MOSFET coupled between the first input terminal and the supply node;

a second switching element which includes a second MOSFET coupled between the second input terminal and the supply node;

first and second substrate diodes each having an anode coupled to a ground node, a cathode of the first diode being coupled to the first input terminal and a cathode of the second diode being coupled to the second input terminal;

a sensor circuit coupled between the supply node and a ground node, the sensor circuit being operable to sense the regulated dc voltage at the supply node and generate a feedback signal therefrom, the feedback signal being coupled to control the first and second switching elements, the sensor circuit including;

a capacitor coupled between the supply node and the ground node;

a voltage divider coupled between the supply node and the ground node, the voltage divider generating a feedback input voltage from the regulated dc voltage;

a comparator that generates the feedback signal by comparing the feedback input voltage to a reference voltage;

wherein the feedback signal disables the first and second switching elements from providing charging current to the supply node when the regulated dc voltage is above a target voltage, and enables the first and second switching elements to provide charging current to the supply node when the regulated dc voltage is below the target voltage.

14. The IC of claim 13 wherein the charging current alternately flows through the first and second substrate diodes during charging of the capacitor.

15. The IC of claim 13 wherein the first switching element further includes a junction field-effect transistor (JFET) coupled between the first input terminal and a drain of the first MOSFET, the second switching element further including a second JFET coupled between the second input terminal and a drain of the second MOSFET.