Dimming circuit with reference control
AssigneeApogee Lighting Holdings, LLC
InventorsFrank Zarcone, James D. Chermak, Fred Katz
Life of this patent
Estimating the term…
Abstract
A balance circuit includes a node on which a reference voltage is generated to control current through a first component string and a first resistor connected to the first component string. A stage receives the reference voltage to generate a tracking current through a second component string and a second resistor connected to the second component string, wherein a current through the first component string is uniformly tracked by the tracking current through the second component string.
Claims20
A balance circuit, comprising:
- a node on which a reference voltage is generated to control current through a first component string and a first resistor connected to both the first component string and the node;
- and
- at least one stage which receives the reference voltage to generate a tracking current through a second component string and a second resistor connected to the second component string, wherein a current through the first component string is uniformly tracked by the tracking current through the second component string.
A balance circuit, comprising:
- a controllable current source;
- a stage having a node on which a reference voltage is generated, the stage including:
- a first component string coupled to the node;
- a first resistor connected to the first component string at the node;
- and
- at least one stage which receives the reference voltage, the at least one stage including:
- a second component string;
- a field effect transistor having a drain coupled to the second component string;
- an operational amplifier which receives the reference voltage at one of its inputs and has an output coupled to a gate of the field effect transistor;
- and
- a second resistor connected to a source of the field effect transistor, wherein a current through the first component string is uniformly tracked through the second component string.
A method for uniformly dimming and brightening light emitting diode strings comprising:
- generating a reference voltage in a balance circuit on a node using a control current of a first component string and a first resistor connected to both the first component string and the node, and at least one stage which receives the reference voltage to generate a tracking current through a second component string and a second resistor connected to the second component string, wherein the control current through the first component string is uniformly tracked by the tracking current through the second component string;
- and
- adjusting a dimmer switch to control the control current through the first component string to uniformly dim or brighten light emitting diode strings in the additional stages.
Dependencies are inferred from the claim text.