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US 8,148,914 B2Granted
Dynamic power saving pulse width modulated LED driver circuit
AssigneeTexas Instruments Incorporated
InventorsJonne J. Sebastian Lindeberg, Tri Cao Nguyen, Suribhotla Rajasekhar
Life of this patent
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Abstract
In accordance with an aspect of the present invention, an LED driving circuit includes a digital-to-analog converter and a driving portion. The circuit is operable to turn off the digital-to-analog converter at times when the driving portion is not providing a high signal. As such the digital-to-analog converter will waste less energy.
Claims20
A circuit for driving a light source, said circuit comprising:
- an input signal provider portion operable to provide a DACzero input signal having a frequency and a DACzero input signal duty cycle including a DACzero input signal high portion and a DACzero input signal low portion;
- an enabling signal providing portion operable to provide an enabling signal having the frequency and an enabling signal duty cycle including an enabling signal high portion and an enabling signal low portion, the enabling signal duty cycle being larger than the DACzero input signal duty cycle;
- a digital-to-analog converter operable to receive a digital input signal and to generate an analog signal based on the DACzero input signal, the enabling signal and the digital input signal;
- and
- a driving portion operable to generate a driving signal to drive the light source, the driving signal being based on the analog signal.
2 more elements
A circuit for driving a light source, said circuit comprising:
- a DACzero input signal provider portion operable to provide a DACzero input signal having a frequency and a DACzero input signal duty cycle including a DACzero input signal high portion and a DACzero input signal low portion;
- an enabling signal providing portion operable to provide an enabling signal having the frequency and an enabling signal duty cycle including an enabling signal high portion and an enabling signal low portion, the enabling signal duty cycle being larger than the DACzero input signal duty cycle;
- a digital-to-analog converter operable to receive a digital input signal and to generate an analog signal based on the digital input signal and a Boolean AND of the input signal high portion and the enabling signal high portion;
- and
- a driving portion comprising a current mirror and a current control feedback portion including a cascade amplifier and a FET, said driving portion being operable to generate a driving signal based on the analog signal, said cascade amplifier having a first input, a second input and an output, said first input being arranged to receive the driving signal, said second input being arranged to receive an analog-based signal that is based on the analog signal, said cascade amplifier being operable to output, from said output, an amplified output signal based on a difference between the driving signal and the analog-based signal, said FET comprising a source, a gate and a drain, said gate being arranged to receive the amplified output signal.
2 more elements
A method of driving a light source, said method comprising:
- providing a DACzero input signal having a frequency and a DACzero input signal duty cycle including a DACzero input signal high portion and a DACzero input signal low portion;
- providing an enabling signal having the frequency and an enabling signal duty cycle including an enabling signal high portion and an enabling signal low portion, the enabling signal duty cycle being larger than the DACzero input signal duty cycle;
- providing a digital input signal;
- generating an analog signal based on the digital input signal, the DACzero input signal and the enabling signal;
- and
- generating the driving signal based on the analog signal.
3 more elements
Dependencies are inferred from the claim text.