US 2016/0098047 A1Published application

Voltage monitoring system

AssigneeFreescale Semiconductor, Inc.

InventorsKumar Abhishek, Aniruddha Gupta, Sunny Gupta, Nitin Pant

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Abstract

An integrated circuit (IC) includes a digital-to-analog converter (DAC), a voltage monitoring circuit, and a controller. The voltage monitoring circuit includes low voltage detect (LVD) and low voltage warning (LVW) circuits that generate LVD and LVW reference voltage signals. The controller generates and stores a voltage margin word (a difference between first and second DAC words that correspond to the LVD and LVW reference voltage signals, respectively). The controller compares the voltage margin word with predetermined maximum and minimum voltage margin words. If the voltage margin word does not lie between the predetermined maximum and minimum voltage margin words, the controller generates a voltage trimming signal that scales the LVW reference voltage signal. After scaling, if the voltage margin word lies between the predetermined maximum and minimum voltage margin words, the controller generates a calibration pass signal, otherwise the controller generates a calibration fail signal.

Claims20

Dependent claims

A system for calibrating a reference voltage signal in an integrated circuit, comprising:

a digital-to-analog converter (DAC) that receives first and second sets of digital control words and generates corresponding first and second sets of control voltage signals during first and second calibration cycles, respectively;
a voltage monitoring circuit, comprising:
a reference voltage generator that generates first and second reference voltage signals;
a first comparator having a first input terminal connected to the DAC for receiving the first set of control voltage signals, a second input terminal connected to the reference voltage generator for receiving the first reference voltage signal, and an output terminal for outputting a first monitor voltage signal during the first calibration cycle;
and
a second comparator having a first input terminal connected to the DAC for receiving the second set of control voltage signals, a second input terminal connected to the reference voltage generator for receiving the second reference voltage signal, and an output terminal for outputting a second monitor voltage signal during the second calibration cycle;
and
a digital controller, connected to the voltage monitoring circuit and the DAC, that receives the first and second monitor voltage signals and generates the first and second sets of digital control words in the first and second calibration cycles, respectively, such that a first reference voltage digital control word of the first set of digital control words corresponds to the first reference voltage signal at the end of the first calibration cycle and a second reference voltage digital control word corresponds to the second reference voltage signal at the end of the second calibration cycle, generates a voltage margin word that corresponds to a difference between the first and second reference voltage digital control words at the end of the first and second calibration cycles, generates a voltage trimming signal based on a comparison between the voltage margin word and at least one of predetermined maximum and minimum reference voltage words and calibrates the second reference voltage signal based on the voltage trimming signal.

5 more elements

A method of calibrating a reference voltage signal of an integrated circuit that includes a digital-to-analog converter (DAC), a voltage monitoring circuit, and a digital controller, comprising:

generating first and second monitor voltage signals based on first and second sets of control voltage signals and first and second reference voltage signals, during first and second calibration cycles, respectively;
generating first and second sets of digital control words corresponding to the first and second sets of control voltage signals during the first and second calibration cycles, respectively, such that a first reference voltage word of the first set of words corresponds to the first reference voltage signal at the end of the first calibration cycle and a second reference voltage digital control word corresponds to the second reference voltage signal at the end of the second calibration cycle;
generating a voltage margin word that corresponds to a difference between the first and second reference voltage digital control words at the end of the first and second calibration cycles;
generating a voltage trimming signal based on a comparison between the voltage margin word with at least one of predetermined maximum and minimum reference voltage words;
and
calibrating the second reference voltage signal based on the voltage trimming signal.

3 more elements

Dependencies are inferred from the claim text.