Noise reduced PWM driver
AssigneeDenso Corporation
InventorHideo Watanabe
Life of this patent
Estimating the term…
Abstract
A PWM driver for driving an electric device by a PWM signal includes an ECU that provides a command signal, first circuit that provides a carrier signal of a triangular shape having a preset frequency, a second circuit that forms a PWM signal having a duty ratio formed based on the carrier signal and the command signal and an output circuit that drives an output device. The second circuit includes a duty ratio limiting circuit that limits the duty ratio of the PWM signal to a range between a first duty ratio and a second duty ratio to prevent the wave shape of the PWM signal from becoming a shape of an impulse.
Claims14
A load driving device, that drives operation of a load, comprising a Pulse Width Modulation (PWM) driver circuit that outputs a PWM signal, the PWM driver circuit:
- having a set lower limit value and a set upper limit value,
- having a duty ratio of the PWM signal set to 0% when an input signal to the PWM driver circuit is equal to or lower than the lower limit value, and
- having the duty ratio of the PWM signal set to 100% when the input signal to the PWM driver circuit is equal to or higher than the upper limit value.
A load driving method in a load driving device, including a Pulse Width Modulation (PWM) driver circuit that outputs a PWM signal, the method comprising:
- setting a lower limit value and an upper limit value;
- the PWM driver circuit outputting a PWM signal with a duty ratio set to 0% when an input signal to the PWM driver circuit is equal to or lower than the lower limit value;
- and
- the PWM driver circuit outputting a PWM signal with a duty ratio set to 100% when the input signal to the PWM driver circuit is equal to or higher than the upper limit value.
A load driving device, that drives operation of a load, comprising a Pulse Width Modulation (PWM) driver circuit that outputs a PWM signal, the PWM driver circuit:
- having a set lower limit value and a set upper limit value,
- having a duty ratio of the PWM signal set to 0% when an input signal to the PWM driver circuit is equal to or lower than the lower limit value,
- having the duty ratio of the PWM signal set to 100% when the input signal to the PWM driver circuit is equal to or higher than the upper limit value and when a first conditions is satisfied, and
- having the duty ratio of the PWM signal set to 0% when the input signal to the PWM driver circuit is equal to or higher than the upper limit value and when the first condition is not satisfied.
A load driving method in a load driving device, including a Pulse Width Modulation (PWM) driver circuit that outputs a PWM signal, the method comprising:
- setting a lower limit value and an upper limit value;
- the PWM driver circuit outputting a PWM signal with a duty ratio set to 0% when an input signal to the PWM driver circuit is equal to or lower than the lower limit value;
- the PWM driver circuit outputting a PWM signal with a duty ratio set to 100% when the input signal to the PWM driver circuit is equal to or higher than the upper limit value and when a first condition is satisfied;
- and
- the PWM driver circuit outputting a PWM signal with a duty ratio set to 0% when the input signal to the PWM driver circuit is equal to or higher than the upper limit value and when the first condition is not satisfied.
Dependencies are inferred from the claim text.