Controller for a switch mode power converter

Patent metadata

Field	Value
Publication number	US-9602013-B2
Application number	US-201414276812-A
Country	US
Kind code	B2
Filing date	May 13, 2014
Priority date	May 13, 2014
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

A controller for controlling a power supply includes a feedback signal generator to generate a feedback signal representative of an output current in response to an output sense signal. A state selector circuit receives the feedback signal and outputs a digital state signal to set an operational state of a switch of the power supply. The state selector circuit adjusts the digital state signal in response to feedback information at an end of a feedback period. A driver circuit receives the digital state signal and generates a drive signal in response to the digital state signal. The drive signal drives switching of the switch in accordance with the operational state of the switch.

First claim

What is claimed is:

1. A control circuit for controlling a switch of a power converter, the control circuit comprising:
a feedback period signal generator coupled to generate a feedback period signal to demarcate a feedback period;
a feedback signal processor coupled to receive a feedback signal representative of an output current of the power converter and output a first signal and a second signal, wherein the first signal is representative of a difference between an estimated average value of the feedback signal and a threshold level, and wherein the second signal is representative of a difference between a portion of the feedback period that the feedback signal is less than a second level and a portion of the feedback period that the feedback signal is greater than a third level, wherein the threshold level corresponds to a desired output current value, wherein the second level is less than the threshold level, and wherein the third level is greater than the threshold level;
a decision circuit coupled to output a direction signal and a mode signal in response to the first signal and the second signal, wherein the direction signal and the mode signal are updated in response to a value of the first signal at the end of the feedback period and a value of the second signal at the end of the feedback period; and
a state counter coupled to receive the direction signal, the mode signal, the first signal, and the second signal, and output a state signal to set an operational state of the switch, wherein the state signal is coupled to be adjusted in response to the direction signal, the mode signal, the value of the first signal at the end of the feedback period, and the value of the second signal at the end of the feedback period.

2. The control circuit of claim 1 , wherein the feedback signal processor includes a first counter coupled to receive a sampling signal and output the first signal, wherein the first counter is coupled to update the first signal every period of the sampling signal in response to a comparison of the feedback signal with the threshold level.

3. The control circuit of claim 2 , wherein the feedback signal processor includes a second counter coupled to receive the sampling signal and output the second signal, wherein the second counter is coupled to update the second signal every period of the sampling signal in response to a comparison of the feedback signal with the second level, and a comparison of the feedback signal with the third level.

4. The control circuit of claim 3 , wherein the second counter is configured to change the value of the second signal if the feedback signal is less than the second level or greater than the third level, and keep the value of the second signal constant if the feedback signal is between the second level and the third level.

5. The control circuit of claim 4 , wherein the first counter and the second counter are further coupled to receive the feedback period signal, wherein the first counter and the second counter are coupled to reset the value of the first signal and the value of the second signal to a first initial value and a second initial value, respectively, at a beginning of a feedback period.

6. The control circuit of claim 5 , wherein the first initial value and the second initial value are equal to each other.

7. The control circuit of claim 1 , wherein the feedback period signal generator is coupled to receive the feedback signal and generate the feedback period signal in response to the feedback signal crossing the threshold level from a level above the threshold level to a level below the threshold level.

8. The control circuit of claim 1 , wherein the feedback period signal generator is coupled to receive an input sense signal representative of an input voltage of the power converter and generate the feedback period signal in response to the input sense signal crossing an input threshold level from a level above the input threshold level to a level below the input threshold level.

9. The control circuit of claim 1 , wherein the decision circuit is coupled to update the direction signal in response to a sign of the first signal.

10. The control circuit of claim 1 , wherein the decision circuit is configured to update the mode signal in response to a magnitude of the first signal, and a magnitude of the second signal and in response to a sign of the first signal, and a sign of the second signal.

11. A controller for a power supply, the controller comprising:
a driver circuit coupled to drive a power switch in a selected one of a plurality of operational states over each one of successive pluralities of switching periods of the power switch; and
a state selector circuit coupled to select one of the operational states for the driving by the driver circuit, wherein the state selector circuit is coupled to transition the driving of the power switch from a first of the operational states over a first plurality of switching periods to a second of the operational states over a second successive plurality of switching periods in regulating an output of the power supply, the state selector comprising:
a first timer coupled to determine a first time during the first plurality of switching periods, the first time corresponding to a difference between a portion of the first plurality of switching periods that an output level of the power supply is less than a desired output level and a portion of the first plurality of switching periods that the output level of the power supply is greater than the desired output level;
a second timer coupled to determine a second time during the first plurality of switching periods, the second time corresponding to a difference between a portion of the first plurality of switching periods that the output level of the power supply is greater than a first level above the desired output level and a portion of the first plurality of switching periods that the output level of the power supply is less than a second level below the desired output level; and
a decision circuit coupled to select one of the operational states of the driver circuit in response to the first time and the second time.

12. The controller of claim 11 , wherein the controller further comprises a period circuitry coupled to demarcate each of the successive pluralities of switching periods of the power switch in response to the output level of the power supply falling below the desired output level.

13. The controller of claim 11 , wherein the controller further comprises a period circuitry coupled to demarcate each of the successive pluralities of switching periods of the power switch in response to an input of the power supply falling below an input threshold level.

14. The controller of claim 11 , wherein each of the pluralities of switching periods of the power switch is an integral number of one half of the period of an ac line voltage to be supplied to the power supply.

15. The controller of claim 11 , wherein the driver circuit is coupled to drive the power switch at a first switching frequency and a first on-time in the first of the operational states, and wherein the driver circuit is coupled to drive the power switch at a second switching frequency and a second on-time in the second of the operational states.

16. The controller of claim 11 , wherein the first on-time is different from the second on-time and the first switching frequency is different from the second switching frequency.

Assignees

• Power Integrations Inc

Inventors

• Pastore Tiziano
• Pregitzer Ricardo Luis Janezic
• Mao Mingming
• Vaughan Peter

Classifications

• H02M2001/0012

  Electricity · mapped topic

• Y02B70/126

  Cross-Sectional Technologies · mapped topic

• H02M2001/0025

  Electricity · mapped topic

• H02M1/4258 Primary

  using a single converter stage both for correction of AC input power factor and generation of a regulated and galvanically isolated DC output voltage (H02M1/4241 takes precedence) · CPC title

• H02M3/33507

  with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence) · CPC title