US 6,720,821 B2 · Methods and systems for generating interim voltage supplies

Abstract

Methods and systems for protecting integrated circuits (“ICs”) from power-on sequencing problems provide an interim voltages during power-on sequences in order to prevent over-voltage conditions across IC terminals. Voltages at first and second terminals of a circuit are monitored and an interim voltage to the second terminal is provided when the voltage at the first terminal exceeds a first threshold and a voltage at the second terminal is below a second threshold. The interim voltage protects the circuit from excessive voltage differences across the first and second terminals during power-on sequences, and is deactivated during normal operation so as not to draw excessive current. The method/system helps to insure that multi-supply dependent logic and/or other circuitry does not receive inappropriate voltage levels, and thus helps to insure that lower voltage level based circuitry is not damaged during power-up, transients, and/or glitches.

Claims24

Dependent claims

A method for protecting a circuit from excessive voltage across first and second terminals of said circuit, comprising the steps of:

(1) sensing first and second voltage amplitudes at said first and second terminals, respectively;
(2) generating an interim voltage amplitude;
(3) coupling said interim voltage amplitude to said second terminal when said first voltage amplitude exceeds a first threshold and said second voltage amplitude is below a second threshold, wherein said interim voltage amplitude is less than said second threshold;
(4) de-coupling said interim voltage amplitude from said second terminal when said second voltage amplitude exceeds said second threshold;
and
(5) de-coupling said interim voltage amplitude from said second terminal when said first voltage amplitude is below said first threshold.

3 more elements

An interim voltage generator for protecting a circuit from excessive voltage differences across first and second inputs of said circuit when a first voltage amplitude is applied to said first input before a second voltage amplitude is applied to said second input, comprising:

said first and second terminals coupled to first and second power supplies, respectively;
a voltage sensor coupled between said first and second terminals, said voltage sensor including first and second thresholds;
a switch having a first contact coupled to said second terminal and a control input coupled to an output of said voltage sensor;
an interim voltage supply coupled to a second contact of said switch, said interim voltage supply providing an interim voltage amplitude that is below said second threshold;
whereby said voltage sensor senses voltage amplitudes at said first and second terminals and controls said switch to couple said interim voltage supply to said second terminal when said voltage amplitude at said first terminal exceeds said first threshold as a result of said first power supply being powered-on, and said voltage amplitude at said second terminal is below said second threshold;
whereby said voltage sensor controls said switch to de-couple said interim voltage supply from said second terminal when said voltage amplitude at said second terminal exceeds said second threshold as a result of said second power supply being powered-on.

3 more elements

Dependencies are inferred from the claim text.

Methods and systems for generating interim voltage supplies

Life of this patent

Methods and systems for generating interim voltage supplies

Life of this patent

Abstract

Claims24