Stacked power supply monitor with sense-replica loop

A system operable to monitor a voltage of power sources in a stacked power supply, comprising:

• a plurality of power sources coupled in series in a stacked arrangement;
• and
• a power monitor configured to measure a voltage across at least one of the power sources, the power monitor comprising:
• a sense module coupled to at least one power source, the sense module configured to convert an input sense voltage VIN across the power source into a corresponding sense current;
• a replica module configured as a replica of the sense module, and referenced to ground, and configured to generate at a replica module output an output sense voltage VOUT based on a mirrored sense current;
• a current mirror configured to mirror the sense current from the sense module into the replica module as the mirrored sense current that generates the output sense voltage VOUT;
• and
• an amplifier with an inverting input coupled to receive a voltage corresponding to the replica sense current, and a noninverting input coupled to a reference voltage referenced to ground, and an output coupled to the replica module output;
• the amplifier establishing a feedback loop configured to cause the output sense voltage VOUT to at least substantially equal the input sense voltage VIN.

A method useable in a stacked power supply to monitor respective voltages of multiple stacked power sources, comprising:

• generating a sense current in a sense cell based on an input sense voltage VIN across a selected power source;
• mirroring the sense current as a mirrored sense current;
• generating from the output of a replica cell referenced to ground an output sense voltage VOUT based on the mirrored sense current;
• establishing a feedback loop to cause the sense current and the mirrored sense current used to generate the output sense voltage VOUT to be substantially equal, such that output sense voltage VOUT is substantially equal to the input sense voltage VIN.