Dimmer decoder with adjustable filter for use with led drivers
AssigneeNational Semiconductor Corporation
InventorSteven M. Barrow
Life of this patent
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Abstract
A method includes receiving a sense signal having multiple pulses, where the sense signal is based on an output of a dimmer. The method also includes, for each of multiple sampling periods, (i) identifying at least one pulse duty cycle for at least one pulse in the sense signal during that sampling period and (ii) generating an output value identifying a duty cycle for driving one or more light emitting diodes (LEDs). The output value is based on the at least one pulse duty cycle. The method further includes filtering the output values using a filter and adjusting the filter based on a rate at which the output of the dimmer changes. The filter could be adjusted by controlling whether an additional resistor forms part of an RC filter based on a sampling state.
Claims20
A method comprising:
- receiving a sense signal comprised of multiple pulses, the sense signal based on an output of a dimmer;
- for each of multiple sampling periods:
- identifying at least one pulse duty cycle for at least one pulse in the sense signal during that sampling period;
- and
- generating an output value identifying a duty cycle for driving one or more light emitting diodes (LEDs), the output value based on the at least one pulse duty cycle;
- filtering the output values using a filter;
- and
- adjusting the filter based on a rate at which the output of the dimmer changes.
A system comprising:
- a driver configured to generate a drive signal for controlling illumination from one or more light emitting diode (LEDs);
- a dimmer decoder configured to:
- receive a sense signal comprised of multiple pulses, the sense signal based on an output of a dimmer;
- for each of multiple sampling periods:
- identify at least one pulse duty cycle for at least one pulse in the sense signal during that sampling period;
- and
- generate an output value identifying a duty cycle for driving the one or more LEDs, the output value based on the at least one pulse duty cycle;
- and
- a filter configured to filter the output values;
- wherein the dimmer decoder is further configured to adjust the filter based on a rate at which the output of the dimmer changes.
An apparatus comprising:
- an output configured to be coupled to a filter;
- and
- a digital block configured to:
- receive a sense signal comprised of multiple pulses, the sense signal based on an output of a dimmer;
- for each of multiple sampling periods:
- identify at least one pulse duty cycle for at least one pulse in the sense signal during that sampling period;
- generate an output value identifying a duty cycle for driving one or more light emitting diodes (LEDs), the output value based on the at least one pulse duty cycle;
- provide the output value to the filter for filtering;
- and
- adjust the filter based on a rate at which the output of the dimmer changes.
Dependencies are inferred from the claim text.