Abstract: An example method of controlling a power supply to have a constant current output includes receiving an input current sense signal, an input voltage sense signal, and an output voltage sense signal. A control signal is then generated to control switching of a switch of the power supply to regulate an output current of the power supply. The generating of the control signal includes integrating the input current sense signal during a switching period of the control signal to generate an integrated signal representative of a charge taken from an input voltage source of the power supply. Generating the control signal also includes controlling the switching of the switch such that the integrated signal is proportional to a ratio of the output voltage sense signal to the input voltage sense signal.

Abstract: A time-differential analog comparator includes a variable frequency signal source, a timing circuit, a counting circuit, and an evaluation circuit. The variable frequency signal source provides a repeating signal having a frequency corresponding to a value of an analog input. The timing circuit defines a timing sequence including a first time interval and a second time interval and generates a mode select signal at a time between the first time interval and the second time interval to stimulate a change in the analog input. The counting circuit is coupled to the timing circuit to count the periods of the repeating signal. The evaluation circuit coupled generates a decision signal in response to a count of the periods of the repeating signal indicated by the counting circuit. The first time interval is not equal to the second time interval to generate an offset in the decision signal.

Abstract: A time-differential analog comparator includes a variable frequency signal source, a timing circuit, a counting circuit, and an evaluation circuit. The variable frequency signal source provides a repeating signal having a frequency corresponding to a value of an analog input. The timing circuit defines a timing sequence including a first time interval and a second time interval and generates a mode select signal at a time between the first time interval and the second time interval to stimulate a change in the analog input. The counting circuit is coupled to the timing circuit to count the periods of the repeating signal. The evaluation circuit coupled generates a decision signal in response to a count of the periods of the repeating signal indicated by the counting circuit. The first time interval is not equal to the second time interval to generate an offset in the decision signal.

Abstract: An example controller for a primary side control power converter includes a feedback circuit, a driver circuit, and an adjustable voltage reference circuit. The feedback circuit is coupled to compare a feedback signal representative of a bias winding voltage of the power converter with a voltage reference. The driver circuit is coupled to output a switching signal to control a switch of the power converter to regulate an output of the power converter in response the feedback circuit. The adjustable voltage reference circuit is coupled to adjust the voltage reference such that the bias winding voltage is adjusted nonlinearly in response to a load condition at the output of the power converter. The adjustable voltage reference circuit is further coupled to detect the load condition in response to the switching signal.

Abstract: An example power supply includes an energy transfer element, a switch and a controller. The controller includes a logic circuit and a constant current control circuit. The logic circuit generates a drive signal to control the switch in response to a control signal. The constant current control circuit generates the control signal in response to a received input current sense signal, input voltage sense signal, and output voltage sense signal. An integrator included in the constant current control circuit integrates the input current sense signal to generate an integrated signal representative of a charge taken from the input voltage source. The constant current control circuit is adapted to generate the control signal to provide a constant current at the output of the power supply such that the integrated signal is proportional to a ratio of the output voltage sense signal to the input voltage sense signal.

Abstract: A time-differential analog comparator is disclosed. An example apparatus according to aspects of the present invention includes a source of a variable frequency signal having a frequency responsive to an analog input. A counting circuit is coupled to count cycles of the variable frequency signal. The counting circuit is coupled to count in a first direction for a first time interval and is coupled to count in a second direction opposite to the first direction for a second time interval that occurs after an end of the first time interval. The counting circuit outputs a digital count signal and an evaluation circuit is coupled to generate a decision signal in response to the digital count signal after an end of the second time interval. The first time interval is not equal to the second time interval to generate an offset in the decision signal.

Abstract: A power supply controller is disclosed. An example power supply controller includes an input voltage sense input coupled to sense an input voltage sense signal representative of an input voltage of a power supply. An output voltage sense input is coupled to sense an output voltage sense signal representative of an output voltage of the power supply. A current limit circuit is coupled to generate a current limit signal. The current limit signal is varied relative to a first ratio representative of a ratio of a product of the input voltage and a scaled output voltage of the power supply, to a sum of the input voltage and the scaled output voltage of the power supply. A drive signal generator is coupled to generate a drive signal in response to the current limit signal to drive the power switch of the power supply to limit an output power of the power supply in response to the input voltage.

Abstract: A power supply includes an energy transfer element having first, second and third windings. An input of the first winding is coupled to an input of the power supply and an output of the second winding is coupled to an output of the power supply. A secondary control circuit is coupled across the second winding to switch a switched element coupled to the second winding in response to a difference between an actual output value and a desired output value to force a current in the third winding that is representative of the difference between the actual output value and the desired output value. A primary control circuit is coupled to a primary switch and to the third winding. The primary control circuit is coupled to switch the primary switch in response to the current forced in the third winding by the secondary control circuit.

Abstract: A controller that forces primary regulation is disclosed. An example controller includes a switched element to be coupled to a second winding of an energy transfer element of a power supply. A secondary control circuit is coupled to the switched element. The secondary control circuit is to be coupled across an output of the second winding to switch the switched element in response to a difference between an actual output value at the output of the second winding and a desired output value to force a current in a third winding of the energy transfer element that is representative of the difference between the actual output value at the output of the second winding and the desired output value. A primary switch is to be coupled to a first winding of the energy transfer element. A primary control circuit is coupled to the primary switch. The primary control circuit is to be coupled to receive the current forced in the third winding of the energy transfer element in response to the secondary control circuit.

Abstract: A time-differential analog comparator is disclosed. An example apparatus according to aspects of the present invention includes a source of a variable frequency signal having a frequency responsive to an analog input. A counting circuit is coupled to count cycles of the variable frequency signal. The counting circuit is coupled to count in a first direction for a first time interval and is coupled to count in a second direction opposite to the first direction for a second time interval that occurs after an end of the first time interval. The counting circuit outputs a digital count signal and an evaluation circuit is coupled to generate a decision signal in response to the digital count signal after an end of the second time interval. The first time interval is not equal to the second time interval to generate an offset in the decision signal.

Abstract: An example controller for a primary side control power converter includes a feedback circuit, a driver circuit, and an adjustable voltage reference circuit. The feedback circuit is coupled to compare a feedback signal representative of a bias winding voltage of the power converter with a voltage reference. The driver circuit is coupled to output a switching signal to control a switch of the power converter to regulate an output of the power converter in response the feedback circuit. The adjustable voltage reference circuit is coupled to adjust the voltage reference such that the bias winding voltage is adjusted nonlinearly in response to a load condition at the output of the power converter. The adjustable voltage reference circuit is further coupled to detect the load condition in response to the switching signal.

Abstract: An example power supply includes an energy transfer element, a switch and a controller. The controller includes a logic circuit and a constant current control circuit. The logic circuit generates a drive signal to control the switch in response to a control signal. The constant current control circuit generates the control signal in response to a received input current sense signal, input voltage sense signal, and output voltage sense signal. An integrator included in the constant current control circuit integrates the input current sense signal to generate an integrated signal representative of a charge taken from the input voltage source. The constant current control circuit is adapted to generate the control signal to provide a constant current at the output of the power supply such that the integrated signal is proportional to a ratio of the output voltage sense signal to the input voltage sense signal.

Abstract: An example apparatus to regulate an output voltage of a power converter at light/no load conditions includes a driver circuit, a feedback circuit, and an adjustable voltage reference circuit. The driver circuit is coupled to output a drive signal to switch a power switch between an ON state and an OFF state to regulate an output of the power converter. The feedback circuit is coupled to the driver circuit and is further coupled to output an enable signal to switch the power switch to an ON state in response to an output voltage signal. The adjustable voltage reference circuit is coupled to adjust a voltage reference such that a bias winding voltage of the power converter is adjusted nonlinearly in response to a load that is to be coupled to the output of the power converter.

Abstract: A time-differential analog comparator is disclosed. An example apparatus according to aspects of the present invention includes a source of a variable frequency signal having a frequency responsive to an analog input. A counting circuit is coupled to count cycles of the variable frequency signal. The counting circuit is coupled to count in a first direction for a first time interval and is coupled to count in a second direction opposite to the first direction for a second time interval that occurs after an end of the first time interval. An evaluation circuit is coupled to the counting circuit. The evaluation circuit is responsive to the count of the cycles of the variable frequency signal after an end of the second time interval.

Abstract: An example controller includes a constant current control circuit and an integrator included in the constant current control circuit. The constant current control circuit is to be coupled to receive an input current sense signal, an input voltage sense signal, and an output voltage sense signal. The control circuit is adapted to regulate an output current of a power supply by generating a control signal to control switching of a switch. The integrator is coupled to integrate the input current sense signal during a switching period of the control signal to generate an integrated signal representative of a charge taken from an input voltage source of the power supply. The constant current control circuit is adapted to control the switching of the switch such that the integrated signal is proportional to a ratio of the output voltage sense signal to the input voltage sense signal.

Abstract: A controller that forces primary regulation is disclosed. An example controller includes a switched element to be coupled to a second winding of an energy transfer element of a power supply. A secondary control circuit is coupled to the switched element. The secondary control circuit is to be coupled across an output of the second winding to switch the switched element in response to a difference between an actual output value at the output of the second winding and a desired output value to force a current in a third winding of the energy transfer element that is representative of the difference between the actual output value at the output of the second winding and the desired output value. A primary switch is to be coupled to a first winding of the energy transfer element. A primary control circuit is coupled to the primary switch. The primary control circuit is to be coupled to receive the current forced in the third winding of the energy transfer element in response to the secondary control circuit.

Abstract: A flyback converter controller with forced primary regulation is disclosed. An example flyback converter controller includes a secondary control circuit to be coupled to a switched element coupled to a second winding of a coupled inductor of a flyback converter. The secondary control circuit is to be coupled across an output of the second winding to switch the switched element in response to a difference between an actual output value at the output of the second winding and a desired output value to force a current in a third winding of the coupled inductor that is representative of the difference between the actual output value at the output of the second winding and the desired output value. A primary control circuit is also included and is to be coupled to a primary switch coupled to a first winding of the coupled inductor. The primary control circuit is to be coupled to receive the current forced in the third winding by the secondary control circuit.

Abstract: A power supply controller is disclosed. An example power supply controller includes an input voltage sense input coupled to sense an input voltage sense signal representative of an input voltage of a power supply. An output voltage sense input is coupled to sense an output voltage sense signal representative of an output voltage of the power supply. A current limit circuit is coupled to generate a current limit signal. The current limit signal is varied relative to a first ratio representative of a ratio of a product of the input voltage and a scaled output voltage of the power supply, to a sum of the input voltage and the scaled output voltage of the power supply. A drive signal generator is coupled to generate a drive signal in response to the current limit signal to drive the power switch of the power supply to limit an output power of the power supply in response to the input voltage.

Abstract: A flyback converter controller with forced primary regulation is disclosed. An example flyback converter controller includes a secondary control circuit to be coupled to a switched element coupled to a second winding of a coupled inductor of a flyback converter. The secondary control circuit is to be coupled across an output of the second winding to switch the switched element in response to a difference between an actual output value at the output of the second winding and a desired output value to force a current in a third winding of the coupled inductor that is representative of the difference between the actual output value at the output of the second winding and the desired output value. A primary control circuit is also included and is to be coupled to a primary switch coupled to a first winding of the coupled inductor. The primary control circuit is to be coupled to receive the current forced in the third winding by the secondary control circuit.

Abstract: A reduced cost energy transfer element for power converter circuits. In one embodiment, an energy transfer element according to an embodiment of the present invention includes a magnetic element having an external surface with at least a first winding and a second winding wound around the external surface of the magnetic element without a bobbin. As such, energy to be received from a power converter circuit input is to be transferred from the first winding to the second winding through a magnetic coupling provided by the magnetic element to a power converter circuit output.