CONTROLLER FOR A SWITCHED MODE POWER CONVERTER

• US 20130094247A1
• Filed: 04/10/2012
• Published: 04/18/2013
• Est. Priority Date: 04/14/2011
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: KLEINPENNING, Jeroen
• Granted Patent: US 9,019,729 B2
• Time in Patent Office: Days
• US Class Current: 363/16
• CPC Class Codes: H02M 3/24 by static converters
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop

Abstract

A switched mode power converter controller outputs a switch control signal for a switch, receives sensed voltage and primary current input signals, and includes a constant current mode controller to process voltage input signals and generate output control signals for controlling converter peak current and/or switching frequency operational; a constant voltage mode controller processes the voltage input signal and generates output control signals for converter peak current and/or switching frequency operational parameters; a primary peak current adjuster processes primary current input and output control signals from the current and voltage mode controllers to configure the switch control signal to turn off the switch; a switching frequency adjuster processes output control signals from the current and voltage controllers to configure the switch control signal to turn on the switch. The constant current controller is enabled if the constant voltage controller signals represent operation with maximum peak current and switching frequency.

Claims

1. A controller for a switched mode power converter having a switch, wherein the switched mode power converter can operate in a constant current and a constant voltage mode of operation, wherein the controller is configured to output a switch control signal for the switch and receive:

a sensed voltage input signal; and

a primary current input signal;

wherein the controller comprises;

a constant current mode controller configured to process the sensed voltage input signal and generate a plurality of output control signals for controlling at least one of peak current and switching frequency operational parameters of the switched mode power converter;

a constant voltage mode controller configured to process the sensed voltage input signal and generate a plurality of output control signals for controlling at least one of the peak current and switching frequency operational parameters of the switched mode power converter;

a primary peak current adjuster configured to process the primary current input signal and at least one of the output control signals from the constant current mode controller and the output control signals from the constant voltage mode controller in order to configure the switch control signal to turn off the switch;

a switching frequency adjuster configured to process at least one of the output control signals from the constant current mode controller and the output signals from the constant voltage mode controller in order to configure the switch control signal to turn on the switch; and

wherein the controller is configured to enable the constant current mode controller if the output control signals of the constant voltage mode controller represent operation with peak current and switching frequency at maximum values.

2. The controller of claim 1, wherein the controller is configured to enable the constant voltage mode controller if the output control signals of the constant current mode controller represent operation with peak current and switching frequency at maximum values.

3. The controller of claim 1, wherein:

the primary peak current adjuster is configured to provide the switch control signal such that it is configured to turn off the switch in order to provide operation with a constant peak current at the maximum value;

or

wherein the switching frequency adjuster is configured to provide the switch control signal such that it is configured to turn on the switch with a constant frequency at the maximum value.

4. The controller of claim 1, configured to enable the constant current controller when the output control signals of the constant voltage mode controller represent operation with the switching frequency and primary peak current are at their maximum values, and the sensed voltage input signal drops to a CC threshold level that is below the voltage level when the switched mode power converter is operating in constant voltage mode.

5. The controller of any preceding claim 1, wherein the controller is configured to operate the switched mode power converter with the maximum values for the switching frequency and primary peak current at the transition between the constant current mode of operation and the constant voltage mode of operation.

6. The controller of claim 1, wherein the switched mode power converter can operate in a regulated current mode of operation, and the controller further comprises:

a regulated current mode controller that comprises;

the constant current mode controller configured to generate output control signals for controlling at least one of the peak current and switching frequency operational parameters of the switched mode power converter such that the output current is maintained substantially constant for sensed voltage input signal levels between the CC threshold level and a fold-back threshold level; and

a fold-back controller configured to generate output control signals for controlling at least one of the peak current and switching frequency operational parameters of the switched mode power converter such that the output current is reduced as the sensed voltage input signal reduces for sensed voltage input signal levels below the fold-back threshold level.

7. The controller of claim 1, wherein the constant current mode controller is configured to generate the output control signal for the switching frequency adjuster and the output control signal for the primary peak current adjuster such that the switching frequency is adjusted for switching frequency values that are above a switching minimum value and the primary peak current is kept constant.

8. The controller of claim 7, wherein the constant current mode controller is configured to generate the output control signal for the switching frequency adjuster and the output control signal for the primary peak current adjuster such that the switching frequency is kept constant at the switching minimum value and the primary peak current is adjusted when the switching frequency reaches the switching minimum value.

9. The controller of claim 1, wherein the primary peak current adjuster is configured to set the on-time of the switch control signal.

10. The controller of claim 1, wherein the primary peak current adjuster is configured to adjust the peak current in accordance with the output control signal from the constant voltage controller when the switched mode power converter operates in a constant voltage mode of operation.

11. The controller of claim 1, wherein the primary peak current adjuster is configured to adjust the peak current in accordance with both of the output control signal from the constant current controller and the output control signal from the constant voltage controller when the switched mode power converter operates in a constant current mode of operation.

12. The controller of claim 1, wherein the primary peak current adjuster comprises a first variable current source that is controllable by the constant voltage controller and a second variable current source that is controllable by the constant current controller, wherein the first and second variable current sources are in parallel with each other and the current from the second variable current source is configured to be subtracted from the current of the first variable current source in order to adjust the primary peak current in the constant current mode of operation.

13. The controller of claim 1, wherein the switching frequency adjuster is configured to adjust the switching frequency in accordance with the output control signal from the constant voltage controller when the switched mode power converter operates in a constant voltage mode of operation.

14. The controller of claim 1, wherein the switching frequency adjuster is configured to adjust the switching frequency in accordance with both of the output control signal from the constant voltage controller and the output control signal from the constant current controller when the switched mode power converter operates in a constant current mode of operation.

15. The controller of claim 1, wherein the switching frequency adjuster comprises a first variable current source that is controllable by the constant voltage controller and a second variable current source that is controllable by the constant current controller, wherein the first and second variable current sources are in parallel with each other and the current from the second variable current source is configured to be subtracted from the current of the first variable current source in order to adjust the switching frequency in the constant current mode of operation.