Patent ID: 7830124

Claim:
A battery monitor circuit having a circuit input, comprising: a control module configured to output a pulse signal; a resistive load having a resistive value between a first and a second terminals and a part of that resistive value between the first and an intermediate terminals; a switch configured to couple the full value of the resistive load between the circuit input and a common potential in response to the pulse signal; a first comparator having inputs coupled separately to a voltage reference and to the intermediate terminal; a second comparator having inputs coupled separately to the voltage reference and to the circuit input; a latch; a detection module having an input coupled to second comparator output, wherein the latch is configured to latch a value at output of the first comparator to another input of the detection module in response to the pulse signal; an alarm module, wherein detection module output is coupled to alarm module input and wherein value of the detection module output is configured to activate the alarm module if an input potential at the circuit input is less than a preselected magnitude; and a step-down module, wherein the second comparator input coupled to the voltage reference is first second-comparator input and the second comparator input coupled to the circuit input is second second-comparator input, wherein the second second-comparator input is coupled to the circuit input through the step-down module, and wherein the step-down module is configured to enable stepping down adjustment of the input potential coupled to the second second-comparator input.