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US 5,703,473 AGranted
Programmable PWM output voltage independent of supply
AssigneeCherry Semiconductor Corporation
InventorsTimothy A. Phillips, J. Eric Lindberg
Life of this patent
Estimating the term…
Abstract
A pulse width modulator that provides a square wave signal whose duty cycle is proportional to a control voltage and inversely related to the power supply voltage applied to the circuit. The pulse width modulator compensates the output voltage applied across a load for variations in the power supply voltage.
Claims35
A pulse width modulator comprising:
- a supply means for receiving a power supply voltage;
- a comparator having a first input and a second input for providing a square wave output;
- an oscillator, coupled to the first input of the comparator, for supplying a periodic ramp voltage having a peak proportional to the power supply voltage;
- an operational amplifier coupled to the supply means and having a feedback loop;
- a transistor included in the feedback loop so that the operational amplifier and the transistor provide a signal proportional to the power supply voltage;
- and
- a summing means, connected to receive the signal proportional to the power supply voltage and a control signal, for supplying a linear combination of the control signal and the power supply voltage to the second input of the comparator.
4 more elements
A pulse width modulator comprising:
- a supply means for receiving a power supply voltage;
- a comparator having a first input and a second input for providing a square wave output;
- an oscillator, coupled to the first input of the comparator, for supplying a periodic ramp voltage having a peak proportional to the power supply voltage;
- and
- an op amp circuit having a first input connected to receive a control signal, a second input connected to receive a signal proportional to the power supply voltage and an output for supplying a linear combination of the control signal and the power supply voltage to the second input of the comparator.
2 more elements
A method for regulating the fraction of time a power supply voltage is connected to a load, comprising the steps of:
- (a) providing a cyclical ramp voltage having an oscillation period and a peak proportional to the power supply voltage;
- (b) creating a linear combination of a control signal and the power supply voltage;
- and
- (c) switching a power device on to connect the load to the power supply voltage during a fraction of the oscillation period dependent upon a comparison between the cyclical ramp voltage and the linear combination of the control signal and the power supply voltage.
1 more element
A pulse width modulated power circuit comprising:
- a supply means for receiving a power supply voltage;
- a power device coupled to said supply means for selectively sourcing output current from the power supply voltage;
- a comparator having a first input and a second input for providing a square wave to control said power device;
- an oscillator, coupled to the first input of the comparator, for supplying a periodic ramp voltage having a peak proportional to the power supply voltage;
- a circuit means for providing a signal proportional to the power supply voltage;
- and
- a summing means, connected to receive the signal proportional to the power supply voltage and a control signal, for supplying a linear combination of the control signal and power supply voltage to the second input of the comparator.
4 more elements
A pulse width modulator comprising:
- a supply means for receiving a power supply voltage;
- a comparator having a first input and a second input for providing a square wave output;
- an oscillator, coupled to the first input of the comparator, for supplying a periodic ramp voltage having a peak proportional to the power supply voltage;
- a voltage divider connected to the supply means so as to provide a signal proportional to the power supply voltage;
- and
- a summing means, connected to receive the signal proportional to the power supply voltage and a control signal, for supplying a linear combination of the control signal and the power supply voltage to the second input of the comparator.
3 more elements
A pulse width modulator comprising:
- a supply means for receiving a power supply voltage;
- a comparator having a first input and a second input for providing a square wave output;
- an oscillator, coupled to the first input of the comparator, for supplying a periodic ramp voltage having a peak proportional to the power supply voltage;
- a current source connected to the supply means to provide a signal proportional to the power supply voltage;
- and
- a summing means, connected to receive the signal proportional to the power supply voltage and a control signal, for supplying a linear combination of the control signal and the power supply voltage to the second input of the comparator.
3 more elements
Dependencies are inferred from the claim text.