Duty Cycle Brightness Control for Lighting Device

摘要

A brightness control circuit for a DC-powered LED light uses a PWM generator. The LED brightness is a function of the duty cycle of a drive signal to a transistor connected in series with the LED. In several embodiments the duty cycle signal generated by the PWM is controlled by at least one momentary SPST switch, or, in one alternative, by first and second SPST switches operable in a make-before-break sequence in a voltage divider circuit.

主权项

1. A brightness control circuit for an LED emitter, comprising:
an LED and a transistor connected in series across a DC voltage source having a source terminal and a return terminal; a microprocessor having a non-volatile memory, the microprocessor connected across the DC voltage source, and an output of the microprocessor connected to an input of the transistor; a switch actuator circuit coupled between at least one input of the microprocessor and the return terminal for entering user commands to select discrete brightness levels of the LED emitter; and a program stored in the non-volatile memory containing control instructions defining a sequence of pulse width modulated signals responsive to the operating state of the switch actuator circuit for controlling the brightness levels of the LED emitter.