Digital control method for improving heavy-to-light (step down) load transient response of switch mode power supplies
AssigneeExar Corporation
InventorsAleksandar Prodic, Zhenyu Zhao
Life of this patent
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Abstract
A method for improving heavy-to-light load transient response in low-power switch-mode power supplies is described. It uses a negative voltage input power rail and a digital controller with an extended duty ratio control value to provide faster discharging current slew rate in the switched mode power supplies (SMPS) inductor.
Claims14
A controller for a DC-DC power supply producing a positive DC output voltage, the controller producing switching signals during a heavy-to-light load transient response such that a negative input voltage is used by the DC-DC power supply;
- and
- wherein the controller uses a duty cycle with a range that includes positive and negative values, positive duty cycle values indicating the portion of a cycle that a positive input voltage is provided rather than ground and negative duty cycle values indicating the portion of a cycle that the negative input voltage is provided rather than ground.
A DC-DC power supply that switches in a positive input voltage, ground and a negative input voltage into an LC circuit so as to produce a positive DC output voltage, the negative input voltage being used during a heavy-to-light load transient response.
A method for a DC-DC power supply comprising:
- during normal operation, switching between a positive input voltage and ground so as to produce a positive DC output voltage;
- and
- during a heavy-to-light load transient, switching between a negative input voltage and ground so as to adjust the positive DC output voltage;
- and
- creating a duty cycle signal with a range that includes positive and negative values;
- and
- wherein positive duty cycles values indicating the portion of a cycle that the positive input voltage is provided, rather than ground, and negative duty cycle values indicating the portion of a cycle that the negative input voltage is provided, rather than ground.
Dependencies are inferred from the claim text.