METHOD AND APPARATUS TO REDUCE MAXIMUM POWER FROM A POWER SUPPLY WITH TRANSITION REGION REGULATION

• US 20100194365A1
• Filed: 04/19/2010
• Published: 08/05/2010
• Est. Priority Date: 06/10/2005
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Currell, Richard W.
• Granted Patent: US 8,188,724 B2
• Time in Patent Office: Days
• US Class Current: 323/282
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop

Abstract

Techniques are disclosed to regulate the output power of a power supply. An example feedback circuit for use in a power supply regulator includes a voltage regulation circuit coupled to sense an output voltage of the power supply regulator. The voltage regulation circuit is coupled to generate a first regulation signal to regulate an output of the power supply regulator if an output current of the power supply is less than a first transition current. A current regulation circuit is coupled to sense an output current of the power supply regulator. The current regulation circuit is coupled to generate a second regulation signal to regulate the output of the power supply regulator if the output voltage of the power supply is less than a second transition voltage. A transition region regulation circuit is coupled to sense the output voltage and the output current of the power supply regulator. The transition region regulation circuit is coupled to generate a third regulation signal to regulate the output of the power supply regulator if the output current of the power supply is between the first transition current and a second transition current. The feedback circuit is coupled to generate a feedback signal output in response to the first, second and third regulation signals.

Claims

1. A feedback circuit for use in a power supply regulator, comprising:

a voltage regulation circuit coupled to sense an output voltage of the power supply regulator, wherein the voltage regulation circuit is coupled to generate a first regulation signal to regulate an output of the power supply regulator if an output current of the power supply is less than a first transition current;

a current regulation circuit coupled to sense an output current of the power supply regulator, wherein the current regulation circuit is coupled to generate a second regulation signal to regulate the output of the power supply regulator if the output voltage of the power supply is less than a second transition voltage; and

a transition region regulation circuit coupled to sense the output voltage and the output current of the power supply regulator, wherein the transition region regulation circuit is coupled to generate a third regulation signal to regulate the output of the power supply regulator if the output current of the power supply is between the first transition current and a second transition current,

wherein the feedback circuit is coupled to generate a feedback signal output in response to the first, second and third regulation signals.

2. The feedback circuit of claim 1 further comprising a summation circuit coupled to receive the first, second and third regulation signals and generate the feedback signal output in response to the first, second and third regulation signals.

3. The feedback circuit of claim 2 wherein the summation circuit is a summation node.

4. The feedback circuit of claim 1 wherein the voltage regulation circuit comprises:

a first Zener diode;

a first resistor coupled to bias the first Zener diode and coupled to receive the output voltage;

a transistor coupled to the first Zener diode and the first resistor; and

a second resistor coupled to the transistor and coupled to receive the output voltage.

5. The feedback circuit of claim 1 wherein the current regulation circuit comprises:

a current sense resistor coupled to sense the output current;

a current summation resistor coupled to the current sense resistor; and

a light emitting diode (LED) of an optocoupler coupled between the current summation resistor and the current sense resistor.

6. The feedback circuit of claim 1 wherein the transition region regulation circuit comprises:

a second Zener diode coupled to receive the output voltage;

a second resistor coupled to bias the second Zener diode;

a second transistor coupled to the second Zener diode and to the second resistor; and

a third resistor coupled to the second transistor.

7. The feedback circuit of claim 1 wherein the transition region regulation circuit comprises:

a third transistor;

a fourth resistor coupled to the third transistor and coupled to receive the output voltage;

a fourth transistor coupled to the third transistor, the fourth resistor and coupled to receive the output voltage;

a fifth transistor coupled to the fourth transistor;

a fifth resistor coupled to the fifth transistor and coupled to receive the output voltage;

a sixth transistor coupled to the fifth transistor;

a sixth resistor coupled to the sixth transistor and coupled to receive the output voltage;

a seventh resistor coupled to the third, fourth and fifth transistors;

an eighth resistor coupled to the third transistor and the seventh resistor; and

a ninth resistor coupled to the fifth and sixth transistors and the eighth resistor.