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US 8,476,882 B2Granted
Reference voltage based equivalent series resistance (ESR) emulation for constant on-time (COT) control of buck regulators
AssigneeExar Corporation
InventorsJia Luo, Jon Cronk, Chuong Nguyen
Life of this patent
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Abstract
The present invention uses a reference voltage that varies within a Pulse Width Modulation (PWM) cycle to generate the PWM signal. This allows for stability in the feedback of Constant On-Time (COT) control for buck controllers when low Equivalent Series Resistance (ESR) capacitors are used as the output capacitor. The reference voltage is adjusted using features of a PWM cycle in a voltage mode without using external inductor current information.
Claims24
An integrated circuit including a buck regulator using Constant On-Time (COT) control comprising:
- reference voltage generating circuitry to produce a reference voltage;
- and
- comparison circuitry to produce a Pulse Width Modulation (PWM) signal, the comparison circuitry receiving the reference voltage from the reference voltage generating circuitry and a feedback voltage from a feedback pin of the integrated circuit;
- wherein the reference voltage generating circuitry produces a reference voltage that varies within a PWM cycle of the PWM signal;
- and
- wherein the reference voltage generating circuitry adjusts the reference voltage based on features of the PWM cycle.
3 more elements
A system comprising:
- comparison circuitry to produce a Pulse Width Modulation (PWM) output, the comparison circuitry receiving the reference voltage from the reference voltage generating circuitry and a feedback voltage from a feedback pin of the integrated circuit;
- wherein the reference voltage generating circuitry produces a reference voltage that varies within a PWM cycle of the PWM signal;
- wherein the reference voltage generating circuitry adjusts the reference voltage based on features of the PWM cycle;
- an external inductor and output capacitor forming a LC circuit for the output voltage and a voltage divider connected to the output voltage to create the feedback voltage for the feedback pin of the integrated circuit;
- and
- wherein the output capacitor is a ceramic capacitor with an Equivalent Series Resistance (ESR) of less than 15 milli-ohms, and the reference voltage generator circuitry adjusts the reference voltage so as to stabilize output voltage for constant on-time control.
3 more elements
Dependencies are inferred from the claim text.