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US 7,029,239 B2Granted
Piecewise linear control of the duty cycle of a pulse width modulated signal
AssigneeStandard Microsystems Corporation
InventorsEileen M. Marando, Robert W. Schoepflin
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Abstract
A system may include a PWM generator and control logic. The PWM generator is configured to generate a PWM signal having a duty cycle dependent on a duty cycle value generated by the control logic. The control logic is configured to generate the duty cycle value to have a piecewise linear relationship with temperature such that at least two of a plurality of linear segments defined by the piecewise linear relationship have different slopes. In some embodiments, the piecewise linear relationship may be continuous.
Claims21
A system, comprising:
- a PWM generator configured to generate a PWM (Pulse Width Modulated) signal having a duty cycle dependent on a duty cycle value;
- and
- control logic coupled to the PWM generator and configured to generate the duty cycle value to have a piecewise linear relationship with temperature, wherein the piecewise linear relationship is defined by a plurality of linear equations, wherein at least two of a plurality of linear segments defined by the piecewise linear relationship have different slopes;
- wherein the control logic is further configured to receive a temperature value representing a current temperature and to select one of the plurality of linear equations dependent on which one of a plurality of portions of a temperature range includes the temperature value, wherein the selected one of the plurality of linear equations is associated with the one of the plurality of portions of the temperature range that includes the temperature value;
- wherein the control logic is further configured to process the temperature value according to the selected one of the plurality of linear equations to generate the duty cycle value;
- wherein a slope of each of the plurality of linear equations relates a range of PWM duty cycle values generated by that one of the plurality of linear equations to the one of the plurality of portions of the temperature range associated with that one of the plurality of linear equations;
- and
- wherein a slope of one of the plurality of linear equations associated with a lower one of the plurality of portions of the temperature range is less than a slope of another one of the plurality of linear equations associated with a higher one of the plurality of portions of the temperature range.
5 more elements
A method, comprising:
- powering a fan according to a PWM (pulse width modulated) signal;
- and
- generating a duty cycle of the PWM signal to have a piecewise linear relationship with temperature, wherein at least two of a plurality of linear segments defined by the piecewise linear relationship have different slopes, wherein the piecewise linear relationship is defined by a plurality of linear equations, wherein each of the plurality of linear equations corresponds to one of a plurality of portions of a temperature range, wherein said generating comprises:
- receiving a temperature value representing a current temperature and selecting one of the plurality of linear equations corresponding to one of the plurality of portions of the temperature range that includes the temperature value;
- and
- processing the temperature value according to the selected one of the plurality of linear equations to determine the duty cycle of the PWM signal;
- wherein a slope of each of the plurality of linear equations relates a range of PWM duty cycle values generated by that one of the plurality of linear equations to the one of the plurality of portions of the temperature range associated with that one of the plurality of linear equations;
- and
- wherein a slope of one of the plurality of linear equations associated with a lower portion of the temperature range is less than a slope of another one of the plurality of linear equations associated with a higher portion of the temperature range.
6 more elements
A system, comprising:
- means for powering a fan according to a PWM (pulse width modulated) signal having a duty cycle dependent on a duty cycle value;
- and
- means for generating the duty cycle value having a piecewise linear relationship with temperature, wherein at least two of a plurality of linear segments defined by the piecewise linear relationship have different slopes, wherein the piecewise linear relationship is defined by a plurality of linear equations;
- wherein the control logic is further configured to receive a temperature value representing a current temperature and to select one of the plurality of linear equations dependent on which one of a plurality of portions of a temperature range includes the temperature value, wherein the selected one of the plurality of linear equations is associated with the one of the plurality of portions of the temperature range that includes the temperature value;
- wherein the control logic is further configured to process the temperature value according to the selected one of the plurality of linear equations to generate the duty cycle value;
- wherein a slope of each of the plurality of linear equations relates a range of PWM duty cycle values generated by that one of the plurality of linear equations to the one of the plurality of portions of the temperature range associated with that one of the plurality of linear equations;
- and
- wherein a slope of one of the plurality of linear equations associated with a lower one of the plurality of portions of the temperature range is less than a slope of another one of the plurality of linear equations associated with a higher one of the plurality of portions of the temperature range.
5 more elements
A system, comprising:
- a PWM generator configured to generate a PWM (Pulse Width Modulated) signal having a duty cycle dependent on a duty cycle value;
- and
- control logic coupled to the PWM generator and configured to generate the duty cycle value to have a piecewise linear relationship with temperature, wherein at least two of a plurality of linear segments defined by the piecewise linear relationship have different slopes, wherein the piecewise linear relationship is defined by a plurality of linear equations that approximate a parabola, wherein a respective slope of each successive one of the plurality of linear equations is higher than a respective slope of any preceding one of the plurality of linear equations;
- wherein the control logic is further configured to receive a temperature value representing a current temperature and to select one of the plurality of linear equations dependent on which one of a plurality of portions of a temperature range includes the temperature value, wherein the selected one of plurality of linear equations is associated with the one of the plurality of portions of the temperature range that includes the temperature value.
1 more element
A method, comprising:
- powering a fan according to a PWM (pulse width modulated) signal;
- and
- generating a duty cycle of the PWM signal to have a piecewise linear relationship with temperature, wherein at least two of a plurality of linear segments defined by the piecewise linear relationship have different slopes, wherein the piecewise linear relationship is defined by a plurality of linear equations that approximate a parabola, wherein each of the plurality of linear equations corresponds to one of a plurality of portions of a temperature range, wherein a slope of one of the plurality of linear equations associated with a lower one of the plurality of portions of the temperature range is less than a slope of another one of the plurality of linear equations associated with a higher one of the plurality of portions of the temperature range, wherein said generating comprises:
- receiving a temperature value representing a current temperature and selecting one of the plurality of linear equations corresponding to one of the plurality of portions of the temperature range that includes the temperature value;
- and
- processing the temperature value according to the selected one of the plurality of linear equations to determine the duty cycle of the PWM signal.
3 more elements
A system, comprising:
- means for powering a fan according to a PWM (pulse width modulated) signal having a duty cycle dependent on a duty cycle value;
- and
- means for generating the duty cycle value having a piecewise linear relationship with temperature, wherein at least two of a plurality of linear segments defined by the piecewise linear relationship have different slopes, wherein the piecewise linear relationship is defined by a plurality of linear equations that approximate a parabola, wherein a respective slope of each successive one of the plurality of linear equations is higher than a respective slope of any preceding one of the plurality of linear equations;
- wherein the control logic is further configured to receive a temperature value representing a current temperature and to select one of the plurality of linear equations dependent on which one of a plurality of portions of a temperature range includes the temperature value, wherein the selected one of plurality of linear equations is associated with the one of the plurality of portions of the temperature range that includes the temperature value.
1 more element
Dependencies are inferred from the claim text.