Smooth brightness adjustment for color-tunable light source module

摘要

A first sequence of pulses having a high frequency can be modulated using a second sequence of pulses having a lower frequency. The pulse width of the second sequence of pulses can be perturbed from a nominal pulse width on a per-pulse basis, within a perturbation range corresponding to the pulse period of the first sequence of pulses. In one application, the resulting output can be used to drive LEDs. In some instances, two or more channels of LEDs of different colors can be supported, with the pulse width of the first pulse sequence being selected per-channel based on a desired light color and the nominal pulse width of the second pulse sequence being selected for all channels based on a desired brightness.

主权项

1. A method comprising:
generating a first pulse sequence using a first pulse-width modulator, the first pulse sequence having a first pulse period corresponding to a high frequency; generating a modulating pulse sequence using a second pulse-width modulator, the modulating pulse sequence having a second pulse period corresponding to a low frequency, wherein generating each modulating pulse in the modulating pulse sequence includes perturbing a width of the modulating pulse by a perturbation amount, the perturbation amount being in a range corresponding to the first pulse period, and wherein different modulating pulses in the sequence are perturbed by different amounts; and modulating the pulse train using the sequence of modulating pulses to produce an output electrical signal.