April 2011 Patents

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SWITCH-MODE POWER SUPPLY (SMPS) WITH AUTO-TUNING USING LIMIT-CYCLE OSCILLATION RESPONSE EVALUATION

Issued November 24, 2009

United States Patent 7,622,820

A switch-mode power supply (SMPS) with auto-tuning using limit-cycle oscillation response evaluation provides optimized performance with reduced capacitance and inductance requirements for a given design. During operation of the SMPS, parameters of the converter are extracted, and the feedback and/or feed-forward compensation is adjusted to either hold the loop bandwidth of the converter near the critical bandwidth of the output capacitors, or maintain output voltage transients within a specified limit. The compensator response is either periodically updated, or is updated in response to an event, such as detection of a transient voltage spike having a characteristic that exceeds one or more predetermined thresholds.

Inventors: Prodic; Aleksandar (Toronto, Ontario, CA), Zhao; Zhenyu (Toronto, Ontario, CA), Schie; David Chalmers (Cupertino, CA)

Appl. No.: 12/107,832

Filed: April 23, 2008

-LIMIT-CYCLE OSCILLATION (LCO) BASED SWITCH-MODE POWER SUPPLY (SMPS) RESPONSE EVALUATION

Issued September 8, 2009

United States Patent 7,586,767

A limit-cycle oscillation (LCO) based switch-mode power supply (SMPS) response evaluation provides an effective mechanism for determining the characteristic response of an SMPS during normal operation of the SMPS. LCOs are induced in the SMPS loop by introducing a non-linearity in the loop, for example, decreasing the resolution of a pulse-width modulator that controls the SMPS switching circuit. The frequency and amplitude of the LCOs are determined and used to evaluate the characteristic response of the SMPS. In order to produce symmetric LCOs, which are more easily modeled, a zero-offset calibration circuit adjusts values provided to the pulse-width modulator, so that each value introduced during calibration is at the midpoint of a resolution cell. The frequency can be measured by counting between zero-crossings of the LCOs and the amplitude measured by capturing the LCO values immediately prior to each zero-crossing of a first difference of the LCO samples.

Inventors: Prodic; Aleksandar (Toronto, Ontario, CA), Zhao; Zhenyu (Toronto, Ontario, CA)

Appl. No.: 12/107,843

Filed: April 23, 2008

These are the patents employed by Maxim to configure its InTune auto-tuning system. The patents were purchased by Maxim from the inventors indicated in the patent disclosures. Fig. 1 is the schematic diagram of the auto-tuning process and Fig. 2 is the flow chart employed to tune the SMPS.

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