APPARATUS AND METHOD FOR DETECTING A CHANGE IN OUTPUT VOLTAGE OF AN ISOLATED POWER CONVERTER

• US 20120170327A1
• Filed: 11/09/2011
• Published: 07/05/2012
• Est. Priority Date: 04/29/2010
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Djenguerian, Alex B., Odell, Arthur B., Wu, Henson
• Granted Patent: US 8,339,811 B2
• Time in Patent Office: Days
• US Class Current: 363/21.12
• CPC Class Codes: H02M 3/335 using semiconductor devices only
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop

Abstract

An output voltage sensor for use in a power converter controller includes a first pulse sampler circuit coupled to receive a feedback signal representative of an output of a power converter. The first pulse sampler circuit is coupled to capture a first peak voltage representative of a second peak of a ringing voltage of the feedback signal at a first time in the feedback signal. A second pulse sampler circuit is coupled to receive the feedback signal representative of the output of the power converter. The second pulse sampler circuit is coupled to capture a second peak voltage representative of the second peak of the ringing voltage of the feedback signal at a second time in the feedback signal. The output voltage sensor is coupled to output a change signal to a drive circuit of the power converter controller in response to the first and second peak voltages.

Claims

1. An output voltage sensor for use in a power converter controller, comprising:

a first pulse sampler circuit coupled to receive a feedback signal representative of an output of a power converter, the first pulse sampler circuit coupled to capture a first peak voltage representative of a second peak of a ringing voltage of the feedback signal at a first time in the feedback signal; and

a second pulse sampler circuit coupled to receive the feedback signal representative of the output of the power converter, the second pulse sampler circuit coupled to capture a second peak voltage representative of the second peak of the ringing voltage of the feedback signal at a second time in the feedback signal, the output voltage sensor coupled to output a change signal to a drive circuit of the power converter controller in response to the first and second peak voltages.

2. The output voltage sensor of claim 1 further comprising a compare circuit coupled to compare the first and second peak voltages, the compare circuit coupled to output the change signal to the drive circuit in response to a comparison of the first and second peak voltages.

3. The output voltage sensor of claim 1 further comprising a first sample signal generator and a second sample signal generator, wherein the first and second sample signal generators are coupled to receive first and second control signals from the drive circuit to initiate first and second samplings of the feedback signal at the first and the second times in the feedback signal, respectively, wherein the first pulse sampler circuit is coupled to capture the first peak voltage in response to the first sample signal generator, wherein the second pulse sampler circuit is coupled to capture the second peak voltage in response to the second sample signal generator.

4. The output voltage sensor of claim 1 wherein the feedback signal is a reflected signal representative of the output of the power supply during an off state of a power switch of the power converter.

5. The output voltage sensor of claim 1 wherein the first and second pulse sampler circuits include first and second capacitors, respectively, coupled to store the first and second peak voltages, respectively.

6. The output voltage sensor of claim 5 wherein the second pulse sampler circuit includes a reset circuit coupled to reset the second capacitor after a predetermined time delay.

7. The output voltage sensor of claim 1 wherein the drive circuit is coupled to generate a switching signal coupled to be received by a power switch coupled to an energy transfer element and an input of the power converter to control a transfer of energy from the input of the power converter to the output of the power converter.