Abstract: Methods and circuits for controlling one or more LEDs are disclosed. In one embodiment, a light emitting diode (LED) driver for driving one or more serially connected LEDs includes a voltage regulator circuit configured to receive a rectified AC voltage, where the voltage regulator circuit includes a depletion device configured to generate an unregulated voltage using the rectified AC voltage, a band gap voltage reference circuit configured to generate one or more reference voltages using the unregulated voltage, and a current setting circuit configured to control the one or more serially connected LEDs using the one or more reference voltages, where the current setting circuit is connected to a circuit ground through a current setting resistor having a fixed resistance value.

Abstract: Methods and circuits for controlling LEDs are disclosed. In one embodiment, a multistage driver for driving a plurality of serially connected LEDs includes a voltage regulator circuit configured to receive a rectified AC voltage, where the voltage regulator circuit includes a depletion device configured to generate a unregulated voltage using the rectified AC voltage, a band gap voltage reference circuit configured to generate a plurality of reference voltages using the unregulated voltage, and a current setting circuit configured to control the plurality of serially connected LEDs using the plurality of reference voltages.

Abstract: Methods and circuits for controlling LEDs are disclosed. In one embodiment, the light emitting diode (LED) integrated circuit controller includes a voltage regulator circuit configured to operate with an alternating current (AC) power source, where the voltage regulator circuit includes a depletion device configured to receive a varying AC voltage and to generate a unregulated voltage, and a band gap voltage reference circuit configured to received the unregulated voltage and to generate a substantially constant direct current (DC) voltage. The LED integrated circuit controller further includes a current setting circuit configured to receive the substantially constant DC voltage and to provide a substantially constant direct current to drive a series of light emitting diodes, and a second depletion device configured to protect the LED integrated circuit controller from external high voltages.