Method and apparatus for sensing multiple voltage values from a single terminal of a power converter controller
A method for regulating an output of a power converter includes receiving a signal from an auxiliary winding of an energy transfer element of the power converter. The energy transfer element includes an input winding coupled to an input of the power converter, an output winding coupled to the output of the power converter, and the auxiliary winding. The signal represents a line input voltage of the power converter during at least a portion of an on time of a power switch coupled to the input winding. The signal represents an output voltage of the power converter during at least a portion of an off time of the power switch. The power switch is switched in response to the signal to regulate the output of the power converter.
1. A method for regulating an output of a power converter, comprising:
receiving a signal from an auxiliary winding of an energy transfer element of the power converter, wherein the energy transfer element includes an input winding coupled to an input of the power converter, an output winding coupled to the output of the power converter, and the auxiliary winding, wherein the signal represents a line input voltage of the power converter during at least a portion of an on time of a power switch coupled to the input winding, and wherein the signal represents an output voltage of the power converter during at least a portion of an off time of the power switch;
sampling the signal during the portion of the off time of the power switch;
generating a sample output voltage signal;
sampling the signal during the portion of the on time of the power switch;
generating a sample input line voltage signal; and
switching the power switch in response to the sample output voltage signal and the sample input line voltage signal to regulate the output of the power converter.
2. The method of claim 1 , further comprising clamping a voltage of the signal during at least the portion of the on time of the power switch.
3. The method of claim 1 , further comprising:
generating a power limit signal in response to the sample input line voltage signal; and
using the power limit signal to limit an input power of the power converter.
4. The method of claim 1 , further comprising responding to the sample output voltage signal by placing the controller into an auto restart mode.