Abstract: An apparatus includes a constant on-time or constant off-time (COT) switching regulator configured to generate an output signal. The switching regulator includes a switch that is turned on or off for a specified amount of time during each of multiple switching cycles. The apparatus also includes a modulator configured to modulate the specified amount of time that the switch is turned on or off during at least some of the switching cycles. The specified amount of time that the switch is turned on or off during each of the switching cycles could be equal to tON/OFF+?tMODF(?MOD), where tON/OFF denotes a constant amount of time, ?tMOD denotes an amplitude of the second signal, ?MOD denotes a frequency of the second signal, and F( ) denotes a modulation function. This could help to modulate switching noise over a range of frequencies and spread electro-magnetic interference generated by the switching regulator.

Abstract: A method includes receiving a control signal associated with a load, where the control signal is to cause a load change from a perspective of a switching-mode power supply. The method also includes causing the power supply to adjust a current through an inductor of the power supply in response to the control signal. The method further includes delaying delivery of the control signal in order to delay a time of the load change, where the current through the inductor increases during the delay. The control signal could include a request to turn on one or more LEDs. The load could include a current regulator. The method could further include providing the request to the current regulator after the delay, such as after the current through the inductor reaches a specified level. Voltage spikes and audible noise in a capacitor coupled to an output of the power supply can be minimized.

Abstract: A method includes receiving a control signal associated with a load, where the control signal is to cause a load change from a perspective of a switching-mode power supply. The method also includes causing the power supply to adjust a current through an inductor of the power supply in response to the control signal. The method further includes delaying delivery of the control signal in order to delay a time of the load change, where the current through the inductor increases during the delay. The control signal could include a request to turn on one or more LEDs. The load could include a current regulator. The method could further include providing the request to the current regulator after the delay, such as after the current through the inductor reaches a specified level. Voltage spikes and audible noise in a capacitor coupled to an output of the power supply can be minimized.

Abstract: A circuit includes a driver configured to generate an output for driving one or more light emitting diodes. The circuit also includes a voltage booster configured to boost an input voltage provided to the driver when the voltage booster is coupled to a high-frequency pulsating alternating current (AC) voltage source that provides the input voltage. The voltage booster may include two first diodes coupled in series, two second diodes coupled in series, and first and second capacitors coupled in series. A first input voltage terminal may be coupled between the first diodes, and a second input voltage terminal may be coupled between the second diodes and between the capacitors. The voltage booster may be further configured to provide the input voltage to the driver without boosting when the voltage booster is coupled to a direct current (DC) or low-frequency AC voltage source that provides the input voltage.

Abstract: A method includes generating an output voltage using a constant on-time or constant off-time (COT) switching regulator. The switching regulator includes a switch and an output capacitor. The method also includes sensing a first current flowing through a sensing capacitor, where the first current is proportional to a second current flowing through the output capacitor. The method further includes controlling the switch based on the sensed first current. Controlling the switch could include generating a feedback voltage using the sensed first current, combining the feedback and output voltages to generate a combined voltage, comparing a scaled version of the combined voltage and a reference voltage, and triggering a one-shot timer based on the comparison. A capacitance of the output capacitor may be greater than a capacitance of the sensing capacitor by a factor of N, and a transimpedance amplifier having a gain based on N could generate the feedback voltage.

Abstract: A method for controlling average current. The method enables control of average current independent of instantaneous current. The average current is controlled by changing the number of unit pulses provided during a time interval. The unit pulses are used to switch the delivery of current to the load.

Abstract: A circuit includes a power converter configured to receive an input voltage and generate a regulated output voltage. The power converter includes an inductor. The circuit also includes a control loop configured to dynamically adjust a valley current limit of the power converter. The valley current limit identifies a minimum current through the inductor during a current-limited mode of operation. The regulated output voltage could be provided to a load configured to operate using the regulated output voltage. The control loop could be configured to dynamically adjust the valley current limit based on an average current through the inductor. The control loop could also be configured to dynamically adjust the valley current limit so that an output current reaches a desired average value during the current-limited mode of operation. The power converter could represent a buck converter, a boost converter, a buck-boost converter, or a hysteretic control power converter.

Abstract: The invention relates to a method and an apparatus for maintaining a substantially constant switching frequency in a relatively fast transient response switching regulator. The apparatus includes a comparison circuit, a one-shot circuit, and a pulse duration controller. The comparison circuit provides a comparison signal to the one-shot circuit based on a comparison of a feedback signal and a reference signal. The one-shot circuit provides a configured duration switch control pulse when the comparison signal is asserted. The pulse duration controller controls the configured duration of the switch control pulse (e.g., duration of a pulse on-time or off-time) to affect the switching frequency of the regulator. In addition, frequency jittering and frequency scaling circuitry may be included.

Abstract: A power supply (10) has a first transistor (20) coupled for switching a coil current (I19) in response to a first control signal (VC1). A second transistor (30) has a body diode (32) for discharging the coil current to produce a power factor corrected signal (VPFC) . A conduction channel (31) of the second transistor is responsive to a second control signal (VC3) for developing a second coil current (I61) from the power factor corrected signal to adjust an output signal of the power supply, where the second control signal commences a time interval (TD2) after the first control signal terminates.

Abstract: A power supply (10) has a first transistor (20) coupled for switching a coil current (Il9) in response to a first control signal (VC1). A second transistor (30) has a body diode (32) for discharging the coil current to produce a power factor corrected signal (VPFC). A conduction channel (31) of the second transistor is responsive to a second control signal (VC3) for developing a second coil current (I61) from the power factor corrected signal to adjust an output signal of the power supply, where the second control signal commences a time interval (TD2) after the first control signal terminates.