Multi-phase switching regulator

Abstract

An N-phase switching voltage regulator includes N current sensing elements which carry respective phase currents. The voltages present at the switch node sides of the sensing elements are summed and presented to an amplifier which also receives the regulator's output voltage, to produce an output which is proportional to the regulator's total output current Iout. The invention also provides a means for direct insertion of total inductor output current information into a regulator's voltage-mode control loop, to provide active voltage positioning (AVP) for the output voltage. A voltage based on total inductor output current is summed with the regulator's reference voltage; this sum and Vout are applied to the voltage control error amplifier, the output of which is processed to operate the regulator's switches. This enables the regulator's output to have a desired droop impedance and to provide AVP of Vout as a function of total filtered inductor output current Iout(fltr).

Description

REFERENCE TO EARLIER APPLICATIONS[0001]This application claims the benefit of provisional patent application No. 60 / 333,404 to Schiff et al., filed Nov. 26, 2001.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]This invention relates to the field of switching voltage regulators, and particularly to multi-phase switching voltage regulators.[0004]2. Description of the Related Art[0005]Switching voltage regulators provide a predetermined and substantially constant output voltage from a source voltage that may be fluctuating, or that may be at an inappropriate amplitude for the load. Such regulators typically employ one or more switching elements. The switching elements may be, for example, field-effect transistor (FET) switches. Control circuitry regulates the current supplied to the load by varying the ON-OFF times of the switching elements (i.e., the regulator's duty cycle, which is the percentage of time that a switch is ON during a cycle of operation). Inductors and ...

AI Technical Summary

Benefits of technology

[0013]The invention also provides a unique means for direct insertion of total inductor output current information into a switching regulator's voltage-mode control loop, to provide AVP for the output voltage. A desired output voltage is specified by providing a reference voltage Vref, and a current circuit—preferably the total current circuit described above—produces an output voltage Vdroop which varies with the the regulator's total filtered instantaneous output current Iout(fltr). A summation circuit produces an output voltage Vset which is given by:Vset=Vref+Vdroop.Vset and Vout are presented to the inputs of a voltage control error amplifier circuit, which produces an output Verr that varies with the difference between Vset and Vout. A control circuit operates the regulator's switches in response to Verr. The control circuit, total current circuit, summation circuit, and voltage control error amplifier circuit are arranged such that the regulator's output has a desired droop impedance Ro, to provide AVP of Vout as a function of the total filtered instantaneous inductor output current Iout(fltr). This serves to directly insert instantaneous inductor output current information into the reference voltage input of the regulator's voltage control error amplifier, which enables fast, accurate control of output voltage for dynamic changes in load.

Problems solved by technology

However, implementing any of the regulators cited above as a multi-phase regulator requires summing and / or sampling data in the controller IC, which can introduce unwanted complexity and processing delays into the IC design.

Another switching regulator issue concerns maintaining the output voltage within specified limits in response to load transients.

However, this approach can result in sluggish and imprecise control on the output voltage for dynamic changes in the load.

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