Patent ID: 8000073
Filing Date: 2011-08-16
Classification: H02H

Abstract:
1. An under voltage lockout (UVLO) circuit comprising: a voltage-to-current converter that generates a proportional current in response to a power supply voltage input to the voltage-to-current converter; a reference current generator that generates a reference current; and a comparator that compares the proportional current to the reference current and in response generates an output signal having a state selected from a first state that indicates that the power supply voltage is insufficient and a second state that indicates that the power supply voltage is sufficient, wherein the comparator includes a hysteretic voltage comparator having an input node connected to compare the reference current to the proportional current and to set the state of the output signal based on the comparison, wherein the comparator includes a first current mirror connected to mirror the reference current and to provide a first mirrored reference current to the input node of the hysteretic voltage comparator and a second current mirror connected to mirror the reference current and to provide a second mirrored reference current to the input node of the hysteretic voltage comparator, wherein the hysteretic voltage comparator provides positive feedback to the second current mirror that selectively prevents the second current mirror from providing the second mirrored reference current to the node connected to the input of the hysteretic voltage comparator based on the state of the output signal such that hysteresis is generated in the comparator.