Circuit for voltage to linear duty cycle conversion
AssigneeHoneywell International Inc.
InventorsChristopher M. Lange, Greg T. Mrozek
Life of this patent
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Abstract
A linear voltage-to-duty cycle converter is disclosed in which an input voltage to be converted is transformed to a triangle wave signal which has up and down ramps whose slopes are variable with the input voltage. A hysteresis comparator receives the triangle wave signal and produces a resulting output signal that has either a high value or a low value depending on the triangle wave signal condition. The time the resultant output signal is high or low compared to the overall time constitutes a duty cycle that is linear with respect to changes in the input voltage.
Claims20
A voltage-to-duty cycle converter comprising:
- a first circuit having a first input to receive the voltage, (Vin), having a second input to receive a second signal and operating to produce a first output in accordance with dV/dt=K1−K2(Vin) when the second signal has a first value and to produce a second output in accordance with dV/dt=K1−K2(Vin)−K3 when the second signal has a second value, where Vin is the input voltage to be converted, K1, K2 and K3 are constants in which K1>K2(Vin) and K3>K1−K2(Vin);
- a second circuit having an input to receive the first and second outputs and operating to produce a resultant output which has a first value when receiving the first output and a second value when receiving the second output, the resultant output having a duty cycle that is linear with Vin;
- and
- connecting means connecting the resultant output to supply the second input to the first circuit.
A voltage, Vin, to duty cycle converter comprising:
- an inverting integrating amplifier having an input which includes a voltage which varies with Vin, said inverting integrating amplifier being operable to produce a triangle wave output signal having up and down ramps whose slopes vary with the input;
- a hysteresis comparator connected to receive the triangle wave output signal and operable to produce a resultant output which is high or low depending on the triangle wave signal;
- and
- connecting means connecting the resultant output of the hysteresis comparator to the input of the inverting integrating amplifier to change the voltage of the input in accordance with the resultant output, the duty cycle of the high and low portions of the output varying with Vin.
A voltage, Vin, to duty cycle converter comprising:
- a first operational amplifier having inverting and non-inverting inputs and an output;
- a second operational amplifier having inverting and non-inverting inputs and an output;
- a source of reference voltage, Vs;
- a switch having “on” and “off” conditions, having an input connected to Vs and having an output to supply Vs when in the “on” condition;
- first means connecting the output of the first operational amplifier to the inverting input of the second operational amplifier;
- second means connecting the output of the second operational amplifier to control the switch to the “on” and “off” conditions;
- third means connecting the non-inverting inputs of the first and second operational amplifiers to Vs;
- fourth means connecting the output of the second operational amplifier to the non-inverting input of the second operational amplifier;
- a first resistor connected between Vin and the inverting input of the first operational amplifier;
- a second resistor connected between the output of the switch and the inverting input of the first operational amplifier;
- and,
- a capacitor connected between the output of the first operational amplifier and the inverting input of the first operational amplifier.
The method of converting an input voltage, Vin, to a pulse train, the duty cycle of which varies with Vin, comprising the steps of:
- A. connecting Vin to the input of an inverting integrating amplifier to produce a triangular wave output having slopes that vary with Vin;
- B. connecting the input of a hysteresis comparator to receive the triangular wave output and to produce a pulse train output of duty cycle which varies with the triangular wave output;
- C. connecting the pulse train output to control the “on” and “off” conditions of a switch to produce an additional voltage when in the “on” condition;
- and
- D. connecting the switch to the input of the inverting integrating amplifier to supply the additional voltage to the input thereof.
Dependencies are inferred from the claim text.