Adaptive pwm controller for multi-phase led driver
AssigneeIntersil Americas Inc.
InventorKI-CHAN LEE
Life of this patent
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Abstract
A multi channel LED driver comprises a plurality of LED strings. Each of the plurality of LED strings are associated with a separate channel. A voltage regulator generates an output voltage to the plurality of LED strings responsive to an input voltage and a PWM control signal. First control logic generates the PWM control signal responsive to a voltage at a bottom of each of the plurality of LED strings. A plurality of dimming circuitries, each connected to one of the bottoms of the plurality of LED strings, control a light intensity in each of the plurality of LED strings responsive to dimming control signals. Second control logic generates the dimming control signals responsive to forward currents monitored through each of the plurality of LED strings and dimming data.
Claims18
A multi channel LED driver, comprising:
- a plurality of LED strings, each associated with a separate channel;
- a voltage regulator for generating on output voltage to the plurality of LED strings responsive to an input voltage and a PWM control signal;
- first control logic for generating the PWM control signal responsive to a voltage at a bottom of each of the plurality of LED strings;
- a plurality of dimming circuitries each connected to one of the bottoms of the plurality of LED strings for controlling a light intensity in each of the plurality of LED strings responsive to dimming control signals;
- and
- second control logic for generating the dimming control signals responsive to forward currents monitored through each of the plurality of LED strings and dimming data.
A multi channel LED driver, comprising:
- a plurality of LED strings, each associated with a separate channel;
- a voltage regulator for generating on output voltage to the plurality of LED strings responsive to an input voltage and a PWM control signal;
- first control logic for generating the PWM control signal responsive to a voltage at a bottom of each of the plurality of LED strings;
- a plurality of dimming circuitries each connected to one of the bottoms of the plurality of LED strings for controlling a light intensity in each of the plurality of LED strings responsive to dimming control signals, each of the plurality of dimming circuitries further comprising:
- a switching transistor connected to a bottom of one of the plurality of LED strings;
- a switch for selectively connecting a reference voltage to a gate of the switching transistor responsive to the dimming control signals;
- second control logic connected to the switching transistor for sensing forward currents through each of the plurality of LED strings and generating a current ratio for each of the plurality of LED strings responsive to the sensed forward currents;
- and
- third control logic for determining a gamma curve for each of the plurality of LED strings responsive to the generated current ratios and for generating the dimming control signals responsive to the determined gamma curves and dimming data.
A method for providing dimming control for a multi channel LED driver, comprising the steps of:
- generating on output voltage to a plurality of LED strings responsive to an input voltage and a PWM control signal;
- generating the PWM control signal responsive to a voltage at a bottom of each of the plurality of LED strings;
- receiving dimming data;
- controlling a light intensity in each of the plurality of LED strings responsive to dimming control signals;
- and
- generating the dimming control signals responsive to forward currents monitored through each of the plurality of LED strings and the dimming data.
A current dimming circuit for use with a multi channel LED driver, comprising:
- a switching transistor connected to a bottom of one of a plurality of LED strings, each of the plurality of strings associated with a channel of the multi channel LED driver;
- a switch for selectively connecting a reference voltage to a gate of the switching transistor responsive to dimming control signals;
- first control logic connected to the switching transistor for sensing the forward currents through each of the plurality of LED strings and generating a current ratio for each of the plurality of LED strings responsive to the sensed forward currents;
- and
- second control logic for determining a gamma curve for each of the plurality of LED strings responsive to the generated current ratios and for generating the dimming control signals responsive to the determined gamma curves and dimming data.
Dependencies are inferred from the claim text.