Dimming control for a switching power supply

A controller for a power supply having a dimmer circuit coupled to an input of the power supply, the controller comprising:

• a measurement block to be coupled to receive an input sense signal and to determine an amount of time that the dimmer circuit disconnects an ac input voltage from the input of the power supply based on the input sense signal;
• and
• a drive circuit coupled to the measurement block and coupled to control switching of a switch included in the power supply, wherein the drive circuit controls switching of the switch in response to a feedback signal when an output of the measurement block indicates that the amount of time is less than or equal to a threshold, and wherein the drive circuit controls switching of the switch independent of the feedback signal when the output of the measurement block indicates that the amount of time is greater than the threshold, wherein the feedback signal is representative of an output quantity of the power supply.

A controller for a power supply having a dimmer circuit coupled to an input of the power supply, the controller comprising:

• a measurement block to be coupled to receive an input sense signal and to generate a dimming control signal in response thereto, wherein the dimming control signal indicates whether an amount of time that the dimmer circuit disconnects an ac input voltage from the input of the power supply is greater than a threshold;
• and
• a drive circuit coupled to the measurement block and to be coupled to control switching of a switch included in the power supply, wherein the drive circuit controls switching of the switch in response to a feedback signal when the dimming control signal indicates that the amount of time is less than or equal to the threshold, and wherein the drive circuit controls switching of the switch independent of the feedback signal when the dimming control signal indicates that the amount of time is greater than the threshold, wherein the feedback signal is representative of an output quantity of the power supply.