Controlled power circuit with adjusted voltage feedback to regulate the output power
A controller for use in a power converter includes a sense circuit coupled to generate a feedback signal representative of an output voltage of the power converter. A feedback reference circuit coupled to generate a drive signal in response to the feedback signal. An output power control circuit coupled to receive a current sense signal representative of an output current of the power converter and a power signal representative of a desired value of an output power of the power converter via an interface. The controller modifies the output voltage to regulate to the output power to the desired value.
1. A controller for use in a power converter, comprising:
a sense circuit coupled to generate a feedback signal representative of an output voltage of the power converter;
a feedback reference circuit coupled to generate a drive signal in response to the feedback signal, wherein the drive signal is used to control switching of a power switch of the power converter to regulate the output voltage; and
an output power control circuit coupled to receive a current sense signal representative of an output current of the power converter and a power signal representative of a desired value of an output power of the power converter via an interface, wherein the output power control circuit generates an adjust signal to adjust the feedback signal such that the controller modifies the output voltage to regulate to the output power to the desired value,
wherein the output power control circuit further comprises:
an analog-to-digital converter (ADC) coupled to receive the current sense signal and provide a measure signal which is a digital representation of the output current; and
a controlled power circuit coupled to receive the measure signal and the power signal, wherein the controlled power circuit determines a calculated value of the output voltage which corresponds with the desired value of the output power and outputs an update signal which updates the adjust signal in response to the calculated value, wherein the update signal is substantially equal to the calculated value if a previous value of the update signal is less than or equal to the calculated value.
2. The controller of claim 1 , wherein the feedback reference circuit is coupled to receive a reference signal.
3. The controller of claim 1 , wherein the feedback reference circuit includes a comparator.
4. The controller of claim 1 , wherein the controller further comprises a drive circuit coupled to generate a primary drive signal to control switching of the power switch in response to the drive signal.
5. The controller of claim 1 , wherein the controller further comprises a drive circuit coupled to generate a secondary drive signal to control switching of a secondary switch in response to the drive signal.
6. The controller of claim 5 , wherein the secondary switch includes a synchronous rectifier.
7. The controller of claim 1 , wherein the interface is an inter-integrated circuit (I2C).
8. The controller of claim 1 , wherein the output power control circuit further comprises a stabilizing transfer circuit coupled to receive the measure signal and output a filter signal to the controlled power circuit, wherein the stabilizing transfer circuit applies a digital transfer function to reshape the measure signal, wherein the controlled power circuit determines the calculated value of the output voltage in response to the filter signal.
9. The controller of claim 8 , wherein the filter signal is a function of a previous value of the filter signal and the measure signal.
10. The controller of claim 1 , wherein the update signal is substantially equal to a previous value of the update signal minus a constant if the previous value of the update signal is greater than the calculated value.
11. The controller of claim 1 , wherein the output power control circuit further comprises:
a range decoder coupled to receive the update signal and output a first and second signal;
a first and second current source coupled to receive the first and second signal, wherein the adjust signal is generated by the first and second current source.
12. A power converter comprising:
an energy transfer element coupled between an input of the power converter and an output of the power converter;
a power switch coupled to the energy transfer element; and
a controller coupled to the power switch to control switching of the power switch to regulate a transfer of energy from an input of the power converter to the output of the power converter, wherein the controller includes:
a sense circuit coupled to generate a feedback signal representative of an output voltage of the power converter;
a feedback reference circuit coupled to generate a drive signal in response to the feedback signal, wherein the drive signal is used to control switching of a power switch of the power converter to regulate the output voltage; and
an output power control circuit coupled to receive a current sense signal representative of an output current of the power converter and a power signal representative of a desired value of an output power of the power converter via an interface, wherein the output power control circuit generates an adjust signal to adjust the feedback signal such that the controller modifies the output voltage to regulate to the output power to the desired value,
wherein the output power control circuit further comprises:
an analog-to-digital converter (ADC) coupled to receive the current sense signal and provide a measure signal which is a digital representation of the output current; and
a controlled power circuit coupled to receive the measure signal and the power signal, wherein the controlled power circuit determines a calculated value of the output voltage which corresponds with the desired value of the output power and outputs an update signal which updates the adjust signal in response to the calculated value, wherein the update signal is substantially equal to the calculated value if a previous value of the update signal is less than or equal to the calculated value.
13. The power converter of claim 12 further comprising a rectifier coupled to the output of the power converter to rectify the output of the power converter.
14. The power converter of claim 13 wherein the rectifier comprises a synchronous rectifier circuit comprising a switch coupled to rectify the output of the power converter.
15. The power converter of claim 14 further comprising a secondary controller coupled to generate a secondary control signal to be received by the synchronous rectifier circuit.
16. The power converter of claim 15 wherein the secondary controller is further coupled to the output power control circuit.
17. The power converter of claim 12 , wherein the output power control circuit further comprises a stabilizing transfer circuit coupled to receive the measure signal and output a filter signal to the controlled power circuit, wherein the stabilizing transfer circuit applies a digital transfer function to reshape the measure signal, wherein the controlled power circuit determines the calculated value of the output voltage in response to the filter signal.
18. The power converter of claim 17 wherein the filter signal is a function of a previous value of the filter signal and the measure signal.
19. The power converter of claim 12 , wherein the update signal is substantially equal to a previous value of the update signal minus a constant if the previous value of the update signal is greater than the calculated value.
20. The power converter of claim 12 , wherein the output power control circuit further comprises:
a range decoder coupled to receive the update signal and output a first and second signal;
a first and second current source coupled to receive the first and second signal, wherein the adjust signal is generated by the first and second current source.