Abstract: In a method for controlling a current regulator for dimming an LED load, a dimming signal has a duty cycle that controls the LED ON-time and LED OFF time at a fixed frequency. The regulator is controlled by the dimming signal to only supply current to the LED load during the LED ON-time. The regulator includes an inductor. The inductor current at the end of an ON-time is detected and its value is stored. During the OFF-time, the inductor is pre-charged to the current level matching the stored value, while the regulator's feedback loop is frozen during the OFF-time to not change its feedback control signal. Upon the next ON-time, the regulator begins supplying current to the LED load with the pre-charged inductor current, so there is no initial decrease in the delivered LED current. Therefore, the current pulse magnitudes are constant even with very low duty cycles.

Abstract: In a method for controlling a current regulator for dimming an LED load, a dimming signal has a duty cycle that controls the LED ON-time and LED OFF time at a fixed frequency. The regulator is controlled by the dimming signal to only supply current to the LED load during the LED ON-time. The regulator includes an inductor. The inductor current at the end of an ON-time is detected and its value is stored. During the OFF-time, the inductor is pre-charged to the current level matching the stored value, while the regulator's feedback loop is frozen during the OFF-time to not change its feedback control signal. Upon the next ON-time, the regulator begins supplying current to the LED load with the pre-charged inductor current, so there is no initial decrease in the delivered LED current. Therefore, the current pulse magnitudes are constant even with very low duty cycles.

Abstract: A circuit for controlling pulsed current to a load, one application of which is in LED dimmer circuitry, comprises first and second reference nodes for receiving a supply voltage, an input node for receiving a timing signal such as a PWM signal, and a controlled switch coupled between the first and second reference voltage nodes for supplying current to the load. Pull-up circuitry may be coupled between a control electrode of the controlled switch and first reference voltage node, and a pull-down switch coupled between the control electrode and second reference voltage node. A control circuit coupled between the input node and control electrode of the controlled switch is configured to control the controlled switch in response to the timing signal. The circuit may further include a reference voltage source configured for producing a voltage of magnitude independent of supply voltage magnitude.