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US 2017/0290115 A1Published application
Arbitrary pulse alignment to reduce led flicker
AssigneeDialog Semiconductor GmbH
InventorsLingxin Kong, Nailong Wang, Ze Han
Life of this patent
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Abstract
An arbitrary alignment is provided for a series of pulses controlling a switch that in turn controls a current in an LED. Each pulse is generated according to a target time responsive to a reference time in a corresponding cycle of a synchronization clock. Each pulse has a leading portion that precedes its target time and a trailing portion subsequent to its target time. The arbitrary alignment defines the relative size of the leading portion to the trailing portion such that these relative sizes are incrementally changed across successive ones of the pulses.
Claims20
A system, comprising:
- a light-emitting diode (LED);
- a switch configured to control a current through the LED responsive to the switch cycling on and off;
- and
- a pulse width modulation (PWM) controller configured to generate a plurality of pulses responsive to a corresponding plurality of cycles of a synchronization clock to control the cycling of the switch, each pulse having a pulse width, wherein the PWM controller is further configured to generate each pulse responsive to a target time defined with regard to a reference time in the corresponding cycle of the synchronization clock such that the pulse has a leading portion of the pulse width that precedes its target time and such that the pulse has a trailing portion of the pulse width subsequent to its target time, and wherein the PWM controller is further configured to change the leading portion by a percentage of the pulse width across successive pulses in a first subset of the plurality of pulses.
1 more element
A method, comprising:
- generating a plurality of pulses responsive to a corresponding plurality of cycles of a synchronization clock, wherein each pulse is generated with regard to a target time defined by a reference time established by the corresponding cycle of the synchronization clock such that each pulse has a leading portion of the pulse width preceding its target time and a remaining trailing portion of the pulse width following its target time;
- cycling a switch on and off responsive to a series of pulses to control a current through a light-emitting diode (LED);
- and
- varying the leading portion by a percentage of the pulse width across successive pulses in a first subset of the plurality of pulses.
1 more element
Dependencies are inferred from the claim text.