Patent ID: 8604710
Filing Date: 2013-12-10
Classification: H05B,Y02B

Abstract:
1. A multi-mode dimming circuit configurable to operate in a first dimming mode, a second dimming mode or a third dimming mode, comprising: a first input terminal; a second input terminal; a third input terminal; an output terminal; a first resistive device having a first terminal coupled to the first input terminal, and a second terminal coupled to the second input terminal; an oscillation circuit having an oscillation input terminal coupled to the third input terminal, and an oscillation output terminal configured to provide an oscillation output signal; and a PWM circuit having a first PWM input terminal coupled to the second input terminal, a second PWM input terminal coupled to the oscillation output terminal, and a PWM output terminal coupled to the output terminal, wherein the PWM circuit is configured to compare a signal at the first PWM input terminal with the oscillation output signal to generate a PWM dimming signal having a first duty cycle and a first frequency; and wherein the multi-mode dimming circuit operates in the first dimming mode when the first input terminal is configured to receive a PWM input signal having a second duty cycle and a second frequency, the second input terminal is coupled to a first capacitive device, and the third input terminal is coupled to a second capacitive device such that the oscillation output signal comprises a first triangle signal; and wherein the multi-mode dimming circuit operates in the second dimming mode when the first input terminal is configured to receive the PWM input signal, the second input terminal is idled, and the third input terminal is coupled to a second resistive device such that the oscillation output signal comprises a DC reference signal; and wherein the multi-mode dimming circuit operates in the third dimming mode when the first input terminal is idled, the second input terminal is configured to receive a DC analog signal, and the third input terminal is coupled to a third capacitive device such that the oscillation output signal comprises a second triangle signal.