Abstract: Techniques are disclosed to adjust a current limit in a switching regulator. One example switching regulator includes a switch to be coupled to an energy transfer element of a power supply. A controller to generate a drive signal is coupled to control switching of the switch to regulate an output of the power supply. A current limiter is included in the controller to adjust the drive signal to limit a current though the switch to a variable current limit value. The variable current limit value is set by the current limiter in response to an input line voltage to be coupled to the energy transfer element.

Abstract: A switching regulator utilizing on/off control that reduces audio noise at light loads by adjusting the current limit of the switching regulator. In one embodiment, a switching regulator includes a state machine that adjusts the current limit of the switching regulator based on a pattern of feedback signal values from the output of the power supply for a preceding N cycles of the drive signal. The state machine adjusts the current limit lower at light loads such that cycles are not skipped to reduce the operating frequency of the switching regulator into the audio frequency range until the flux density through the transformer is sufficiently low to reduce the generation of audio noise.

Abstract: A regulator circuit maintaining an approximate constant current output characteristic. In one aspect, a disclosed regulator controls a switch that has a current limit threshold. A supply terminal and feedback terminal of the regulator are connected together as a control terminal such that a shunt regulator current is the control terminal current in excess of the internal supply current consumed by the regulator. The current limit threshold of the switch is changed as a function of the shunt regulator current. In another aspect, a control input of the regulator circuit receives a current that is the sum of the internal supply current consumed by the regulator circuit and a feedback current. The feedback current is a fraction of the consumption current of the regulator circuit and the current limit threshold of the switch is changed as a function of the feedback current.

Abstract: Techniques are disclosed to regulate an output of a power converter. One example power converter controller circuit includes a line sense input to be coupled to receive a signal representative of an input voltage of a power converter. A feedback input is included and is to be coupled to receive a feedback signal representative of an output of the power converter. A drive signal generator is included and is to generate a drive signal coupled to control switching of a switch to provide a regulated output parameter at the output of the power converter in response to the feedback signal. The drive signal generator is to latch the power converter into an off state in response to a detection of a loss of regulation of a power converter output parameter if the input voltage of the power converter is above a threshold level. The drive signal generator is to be unresponsive to the signal representative of the input voltage of the power converter while the power converter output parameter is in regulation.

Abstract: Various techniques directed to the digital control of a switching regulator are disclosed. In one aspect, a power supply regulator includes a compare circuit to be coupled to receive a feedback signal representative of an output level of a power supply. This causes a feedback state signal to be generated having a first feedback state that represents an output level of the power supply that is above a threshold level and a second feedback state that represents an output level of the power supply that is below the threshold level. An adjustment circuit is coupled to the compare circuit to adjust the feedback state signal in response to at least one of adjusting the threshold level or adjusting the feedback signal. The adjustment to the feedback state signal tends to cause the feedback state signal to revert from a state at the time of adjustment to a state immediately preceding the adjustment.

Abstract: A power supply including a regulation circuit that maintains an approximately constant load current with line voltage. In one embodiment, a regulation circuit includes a semiconductor switch and current sense circuitry to sense the current in the semiconductor switch. The current sense circuitry has a current limit threshold. The regulation circuit current limit threshold is varied from a first level to a second level during the time when the semiconductor switch is on. One embodiment of the regulation circuit is used in a power supply having an output characteristic having an approximately constant output voltage below an output current threshold and an approximately constant output current below an output voltage threshold.

Abstract: Techniques are disclosed to adjust a current limit in a switching regulator. One example switching regulator includes a switch to be coupled to an energy transfer element of a power supply. A controller to generate a drive signal is coupled to control switching of the switch to regulate an output of the power supply. A current limiter is included in the controller to adjust the drive signal to limit a current though the switch to a variable current limit value. The variable current limit value is set by the current limiter in response to an input line voltage to be coupled to the energy transfer element.

Abstract: Techniques are disclosed to regulate an output of a power converter. One example power converter includes an energy transfer element coupled between an input and an output of the power converter. A switch included in the power converter is coupled to the input of the energy transfer element. The power converter also includes a controller circuit coupled to the switch. The controller circuit is also coupled to receive a feedback signal representative of the output of the power converter and coupled to receive a signal representative of the power converter input voltage. The controller circuit is coupled to control switching of the switch to provide a regulated output parameter at the output of the power converter in response to the feedback signal. The controller circuit is coupled to latch the power converter into an off state in response to a detection of a loss of regulation of a power converter output parameter if the power converter input voltage is above a threshold level.

Abstract: Various techniques directed to the digital control of a switching regulator are disclosed. In one aspect, a method for regulating an output level at a power converter output includes receiving a feedback signal representative of the output level at the power converter output. In response to a state of the power converter, at least one of the feedback signal or a threshold level is adjusted. A feedback state signal is generated having a first feedback state that represents that the output level is above the threshold level and a second feedback state that represents that the output level is below the threshold level. A duty cycle signal that cycles is generated. In response to a control signal, energy from a power converter input is enabled or disabled to flow to the power converter output. The control signal is responsive to the duty cycle signal and to a change between the first and second feedback states. The control signal is also responsive to a change between the first and second feedback states.

Abstract: Techniques are disclosed to adjust a current limit in a switching regulator. One example switching regulator includes a switch to be coupled to an energy transfer element of a power supply. A controller to generate a drive signal is coupled to control switching of the switch to regulate an output of the power supply. A current limiter is included in the controller to adjust the drive signal to limit a current though the switch to a variable current limit value. The variable current limit value is set by the current limiter in response to an input line voltage to be coupled to the energy transfer element.

Abstract: A power supply including a regulation circuit that maintains an approximately constant load current with line voltage. An example circuit includes a switch including first, second and third terminals. The first terminal is coupled or decoupled to the second terminal in response to a control signal received at the third terminal. Voltage sense circuitry is included and is coupled to sense a voltage drop across the switch. The voltage drop is representative of a current in the switch during an on time of the switch. The voltage sense circuitry has a variable current limit threshold that increases between a first level and a second level during the on time of the switch. The control signal is responsive to the variable current limit threshold to regulate a power supply with an output characteristic having an approximately constant output voltage below an output current threshold and an approximately constant output current below an output voltage threshold.

Abstract: A switching regulator utilizing on/off control that reduces audio noise at light loads by adjusting the current limit of the switching regulator. In one embodiment, a switching regulator includes a state machine that adjusts the current limit of the switching regulator based on a pattern of feedback signal values from the output of the power supply for a preceding N cycles of the drive signal. The state machine adjusts the current limit lower at light loads such that cycles are not skipped to reduce the operating frequency of the switching regulator into the audio frequency range until the flux density through the transformer is sufficiently low to reduce the generation of audio noise.

Abstract: Various techniques directed to the digital control of a switching regulator are disclosed. In one aspect, a method for regulating an output level at a power converter output includes receiving a feedback signal representative of the output level at the power converter output. In response to a state of the power converter, at least one of the feedback signal or a threshold level is adjusted. A feedback state signal is generated having a first feedback state that represents that the output level is above the threshold level and a second feedback state that represents that the output level is below the threshold level. A duty cycle signal that cycles is generated. In response to a control signal, energy from a power converter input is enabled or disabled to flow to the power converter output. The control signal is responsive to the duty cycle signal and to a change between the first and second feedback states. The control signal is also responsive to a change between the first and second feedback states.

Abstract: Techniques are disclosed to select functional parameters and/or operating modes of a circuit based on a time measurement are disclosed. One example integrated circuit includes a threshold detection and timing circuit that is coupled to measure a signal during an initialization period of the integrated circuit from a multifunction capacitor that is to be coupled to a first terminal of the integrated circuit. A selection circuit is coupled to the threshold detection and timing circuit to select a parameter/mode of the integrated circuit in response to the measured signal from the multifunction capacitor during the initialization period of the integrated circuit. The multifunction capacitor is coupled to provide an additional function for the integrated circuit after the initialization period of the integrated circuit is complete.

Abstract: A regulator circuit maintaining an approximate constant current output characteristic. In one aspect, a disclosed regulator controls a switch that has a current limit threshold. A supply terminal and feedback terminal of the regulator are connected together as a control terminal such that a shunt regulator current is the control terminal current in excess of the internal supply current consumed by the regulator. The current limit threshold of the switch is changed as a function of the shunt regulator current. In another aspect, a control input of the regulator circuit receives a current that is the sum of the internal supply current consumed by the regulator circuit and a feedback current. The feedback current is a fraction of the consumption current of the regulator circuit and the current limit threshold of the switch is changed as a function of the feedback current.

Abstract: A method is disclosed to add functionality to a terminal of a high voltage integrated circuit without the penalty of additional high voltage circuitry. The benefit is that alternative modes of operation can be selected for testing, trimming parameters of the integrated circuit, or any other purpose without the cost of an additional terminal. In one embodiment, ordinary low voltage circuitry monitors the voltage on the terminal that normally is exposed to high voltage. The configuration of a simple voltage detector and an ordinary latch allows easy entry into the test and trimming mode when the integrated circuit is not in the intended application, but prohibits entry into the test and trimming mode when the integrated circuit operates in the intended application.

Abstract: Techniques are disclosed to regulate an output of a power converter. One example power converter includes an energy transfer element coupled between an input and an output of the power converter. A switch included in the power converter is coupled to the input of the energy transfer element. The power converter also includes a controller circuit coupled to the switch. The controller circuit is also coupled to receive a feedback signal representative of the output of the power converter and coupled to receive a signal representative of the power converter input voltage. The controller circuit is coupled to control switching of the switch to provide a regulated output parameter at the output of the power converter in response to the feedback signal. The controller circuit is coupled to latch the power converter into an off state in response to a detection of a loss of regulation of a power converter output parameter if the power converter input voltage is above a threshold level.

Abstract: Techniques are disclosed to adjust a current limit in a switching regulator. One example switching regulator includes a switch to be coupled to an energy transfer element of a power supply. A controller to generate a drive signal is coupled to control switching of the switch to regulate an output of the power supply. A current limiter is included in the controller to adjust the drive signal to limit a current though the switch to a variable current limit value. The variable current limit value is set by the current limiter in response to an input line voltage to be coupled to the energy transfer element.

Abstract: Techniques are disclosed to extend an on time period of switch to regulate a transfer of energy from an input of a power supply to an output of a power supply. One example integrated circuit includes an energy transfer element coupled between an input and an output of the power supply. A switch is coupled to the input of the energy transfer element. A controller is coupled to the switch to control switching of the switch to regulate a transfer of energy from the input of the power supply to the output of the power supply in response to a feedback signal received from the output of the power supply. The controller is coupled to limit a maximum on time period of the switch a first maximum on time period in response to a first range of power supply operating conditions and to a second maximum on time period for a second range of power supply operating conditions.

Abstract: A method is disclosed to add functionality to a terminal of a high voltage integrated circuit without the penalty of additional high voltage circuitry. The benefit is that alternative modes of operation can be selected for testing, trimming parameters of the integrated circuit, or any other purpose without the cost of an additional terminal. In one embodiment, ordinary low voltage circuitry monitors the voltage on the terminal that normally is exposed to high voltage. The configuration of a simple voltage detector and an ordinary latch allows easy entry into the test and trimming mode when the integrated circuit is not in the intended application, but prohibits entry into the test and trimming mode when the integrated circuit operates in the intended application.