US 2017/0251535 A1 · DIMMING CIRCUIT, CONTROL CIRCUIT AND DIMMING METHOD

Abstract

A dimming circuit for adjusting the brightness of an LED load, can include: a primary controlled flyback converter having a primary-side circuit, a first secondary-side circuit, and a second secondary-side circuit; a DC-DC converter coupled in a cascade arrangement with the second secondary-side circuit, where an output node of the DC-DC converter is coupled in series to an output node of the first secondary-side circuit; a control circuit configured to control, according to a dimming signal that represents an expected output current of the dimming circuit, a power switch of the primary controlled flyback converter to adjust output voltages of the first and second secondary-side circuits, to adjust a power that is provided to the LED load; and the control circuit being configured to control a power switch of the DC-DC converter according to the dimming signal, such that the DC-DC converter operates within a predetermined state range.

Claims18

Dependent claims

A dimming circuit for adjusting the brightness of an LED load, the dimming circuit comprising:

a) a primary controlled flyback converter having a primary-side circuit, a first secondary-side circuit, and a second secondary-side circuit;
b) a DC-DC converter coupled in a cascade arrangement with said second secondary-side circuit, wherein an output node of said DC-DC converter is coupled in series to an output node of said first secondary-side circuit;
c) a control circuit configured to control, according to a dimming signal that represents an expected output current of said dimming circuit, a power switch of said primary controlled flyback converter to adjust output voltages of said first and second secondary-side circuits, in order to adjust a power that is provided to said LED load;
and
d) said control circuit being configured to control a power switch of said DC-DC converter according to said dimming signal, such that said DC-DC converter operates within a predetermined state range.

2 more elements

A method of adjusting the brightness of an LED load, the method comprising:

a) controlling, by a control circuit, a power switch of a primary controlled flyback converter to adjust output voltages of first and second secondary-side circuits, in order to adjust a power that is provided to an LED load, wherein said controlling is according to a dimming signal that represents an expected output current of said dimming circuit;
b) controlling, by said control circuit, a power switch of a DC-DC converter according to said dimming signal, such that said DC-DC converter operates within a predetermined state range, wherein said DC-DC converter is coupled in a cascade arrangement with said second secondary-side circuit, and wherein an output node of said DC-DC converter is coupled in series to an output node of said first secondary-side circuit;
and
c) adjusting, by a reference voltage adjustment circuit, a reference voltage of said primary controlled flyback converter according to said dimming signal, wherein said reference voltage represents an expected output voltage of said primary controlled flyback converter.

1 more element

Dependencies are inferred from the claim text.

Dimming circuit, control circuit and dimming method

Life of this patent

Dimming circuit, control circuit and dimming method

Life of this patent

Abstract

Claims18