Patent ID: 7919928

Claim:
A light emitting diode (LED) driver for driving a plurality of LEDs connected in series, the driver comprising: a current regulator configured to boost an input voltage to drive the plurality of LEDs with a boosted output voltage, the current regulator comprising: a feedback circuit comprising a first resistor and first capacitor connected in series, a first terminal of the first resistor being connected to receive a signal corresponding to a pulsed current through the plurality of LEDs, a second terminal of the first resistor being connected to a first terminal of the first capacitor, the first terminal of the capacitor providing a feedback voltage; an error amplifier having inputs comprising the feedback voltage and a reference voltage, an output of the error amplifier determining a control voltage; a switching transistor connected to be switched at a duty cycle corresponding to a magnitude of the control voltage, the duty cycle corresponding to a peak current generated by the current regulator; an inductor connected to a first terminal of the switching transistor and to the input voltage for providing a varying current as the switching transistor is turned on and off; and a first terminal of the switching transistor being connected to an anode of an LED in the plurality of LEDs connected in series, with no smoothing capacitor connected to the anode, such that pulses of current are conducted through the LEDs as the switching transistor turns on and off, wherein a magnitude of the feedback voltage from the first capacitor is controlled by the current regulator to be approximately equal to the reference voltage by the current regulator controlling the duty cycle of the switching transistor.