Control with hysteresis of an electronic device using a pulse-width modulated signal
AssigneesContinental Automotive France, Continental Automotive GmbH
InventorsFrédéric Le-Hung, Stéphane Saint-Macary
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Abstract
A device and switching method for a circuit for generating an output voltage (Vout) via a control signal (CTRL) with two pulse-width modulated states are described. The control signal (CTRL) frequency (Fq) is measured. In order to generate the control signal (CTRL), either a first hysteresis comparator (31) or a second hysteresis comparator (32) is enabled depending on the control signal (CTRL) measured frequency (Fq). Advantageously, the voltage thresholds of the hysteresis comparators and at least one frequency threshold can be chosen in such a manner as to avoid the control signal (CTRL) frequency (Fq) entering into forbidden frequency bands.
Claims20
An electronic device comprising:
- a switched circuit having an output designed to deliver an output voltage, and controlled by a control signal with two pulse-width modulated states;
- a first hysteresis comparator, with a first low-voltage threshold and a first high-voltage threshold higher than said first low-voltage threshold, designed to generate the control signal depending on a comparison between the output voltage and the first low-voltage threshold and the first high-voltage threshold;
- at least a second hysteresis comparator, with a second low-voltage threshold and a second high-voltage threshold higher than said second low-voltage threshold, designed to generate the control signal depending on a comparison between the output voltage and the second low-voltage threshold and the second high-voltage threshold, a difference between the second high-voltage threshold and the second low-voltage threshold being less than a difference between the first high-voltage threshold and the first low-voltage threshold;
- and
- a control unit (34) adapted to measure a control signal frequency, and for enabling either the first hysteresis comparator or the second hysteresis comparator depending on the control signal measured frequency, the first hysteresis comparator being enabled for relatively control signal low frequencies, and the second hysteresis comparator being enabled for relatively control signal high frequencies.
A switching method for a circuit designed to generate an output voltage starting from a control signal with two pulse-width modulated states, comprising:
- measuring control signal frequency;
- and,
- enabling a first hysteresis comparator or a second hysteresis comparator depending on the measured control signal frequency, in order to generate the control signal,
- in which:
- the first hysteresis comparator having a first low-voltage threshold and a first high-voltage threshold higher than said first low-voltage threshold, and being adapted to generate the control signal depending on a the comparison between the output voltage, the first low-voltage threshold and the first high-voltage threshold, is enabled for relatively low frequencies of the control signal;
- and,
- the second hysteresis comparator having a second low-voltage threshold and a second high-voltage threshold higher than said second low-voltage threshold, and being adapted to generate the control signal depending on comparison between the output voltage, the second low-voltage threshold and the second high-voltage threshold, is enabled for relatively high frequencies of the control signal,
- and in which:
- a difference between the second high-voltage threshold and the second low-voltage threshold is lower than a difference between the first high-voltage threshold and the first low-voltage threshold.
Dependencies are inferred from the claim text.