Methods and apparatus for monitoring a level of a regulated source

A method for monitoring a voltage level of a first regulated voltage and a second regulated voltage, comprising:

• providing a first voltage source configured to generate the first regulated voltage to power a first circuit;
• providing a second voltage source configured to generate the second regulated voltage to power a second circuit;
• comparing the first regulated voltage to the second regulated voltage using a first comparator to generate a first error signal indicative of at least one of an overvoltage condition of the first regulated voltage and an undervoltage condition of the second regulated voltage, the first comparator having a first input coupled to the first regulated voltage and a second input coupled to the second regulated voltage, wherein a first resistor divider is coupled to the first regulated voltage, and wherein the first resistor divider is coupled to the first comparator and to a second comparator;
• and
• comparing the second regulated voltage to the first regulated voltage using a second comparator to generate a second error signal indicative of at least one of an undervoltage condition of the first regulated voltage and an overvoltage condition of the second regulated voltage, the second comparator having a first input coupled to the first regulated voltage and a second input coupled to the second regulated voltage, wherein a second resistor divider is coupled to the second regulated voltage, and wherein the second resistor divider is coupled to the first comparator and to the second comparator.

A monitor circuit for monitoring a voltage level of a first regulated voltage to power a first circuit and a second regulated voltage to power a second circuit, a monitor circuit comprising:

• a first comparator powered by the first regulated voltage and having a first input coupled to a divided version of the first regulated voltage and a second input coupled to a divided version of the second regulated voltage to generate a first error signal indicative of at least one of an overvoltage condition of the first regulated voltage and an undervoltage condition of the second regulated voltage;
• a second comparator powered by the second regulated voltage and having a first input coupled to a divided version of the first regulated voltage and a second input coupled to a divided version of the second regulated voltage to generate a second error signal indicative of at least one of an undervoltage condition of the first regulated voltage and an overvoltage condition of the second regulated voltages;
• a first resistor divider coupled to the first regulated voltage to generate a first voltage, wherein the first input of the first comparator is coupled to the first voltage, wherein the first resistor divider is coupled to the first comparator and to the second comparator, and
• a second resistor divider coupled to the second regulated voltage to generate a second voltage, wherein the second input of the second comparator is coupled to the second voltage, wherein the second resistor divider is coupled to the first comparator and to the second comparator.

A monitor circuit for monitoring a voltage level of a first regulated voltage generated by a first regulator and a second regulated voltage generated by a second, different regulator, the monitor circuit comprising:

• a first circuit comprising a first comparator powered by the first regulated voltage, the first comparator having a first input responsive to the first regulated voltage and a second input responsive to the second regulated voltage to generate a first error signal indicative of at least one of an overvoltage condition of the first regulated voltage and an undervoltage condition of the second regulated voltage;
• a second circuit comprising a second comparator powered by the second regulated voltage, the second comparator having a first input responsive to the first regulated voltage and a second input responsive to the second regulated voltage to generate a second error signal indicative of at least one of an undervoltage condition of the first regulated voltage and an overvoltage condition of the second regulated voltage;
• and
• wherein the first regulated voltage is provided at an output of the first regulator and the second regulated voltage is provided at an output of the second regulator and wherein the first regulated voltage has a voltage level that is substantially the same as the second regulated voltage.

A monitor circuit for monitoring a voltage level of a first regulated voltage and a second regulated voltage, the monitor circuit comprising:

• a first circuit comprising a first comparator powered by the first regulated voltage, the first comparator having a first input responsive to the first regulated voltage and a second input responsive to the second regulated voltage to generate a first error signal indicative of at least one of an overvoltage condition of the first regulated voltage and an undervoltage condition of the second regulated voltage;
• a second circuit comprising a second comparator powered by the second regulated voltage, the second comparator having a first input responsive to the first regulated voltage and a second input responsive to the second regulated voltage to generate a second error signal indicative of at least one of an undervoltage condition of the first regulated voltage and an overvoltage condition of the second regulated voltage;
• and
• wherein at least one of the first and second comparators has hysteresis.