Methods and Apparatus for Resistive Voltage Sensing in an Isolated Power Distribution Unit

Abstract

Methods and apparatus provide for a primary side circuit including one or more voltage nodes; and a monitoring circuit operating to monitor one or more parameters of the primary side circuit, and including at least one sensing circuit and at least one processing circuit within a secondary side circuit, where the sensing circuit includes a resistor network having an input for receiving a first sensed voltage from a first of the voltage nodes of the primary side circuit, traversing an isolation boundary between the primary side circuit and the secondary side circuit while adhering to a safety specification, which includes a primary-secondary isolation requirement, and having an output for providing a first modified sensed voltage to the processing circuit.

What is claimed is: 
     
         1 . An apparatus, comprising:
 a primary side circuit including one or more voltage nodes;   a secondary side circuit including at least one processing circuit; and   a resistor network having an input for receiving a first sensed voltage from a first of the one or more voltage nodes of the primary side circuit, traversing an isolation boundary between the primary side circuit and the secondary side circuit while adhering to a safety specification which includes a primary-secondary isolation requirement, and having an output for providing a first modified sensed voltage to the processing circuit; and   wherein said resistor network does not bridge any isolation circuit.   
     
     
         2 . The apparatus of  claim 1 , wherein the resistor network includes:
 a plurality of series-coupled resistors, which are connected at one end to the first voltage node of the primary side circuit, and are connected at an opposite end to a junction node; a shunt resistance coupled from the junction node to a reference potential; and   the output providing the first modified sensed voltage to the processing circuit is at least one of taken from, and derived from, a voltage at the junction node.   
     
     
         3 . The apparatus of  claim 2 , wherein:
 the first voltage node of the primary side circuit exhibits a single ended voltage potential with respect to the reference potential; and   the output providing the first modified sensed voltage to the processing circuit is a single ended voltage taken from the junction node with respect to the reference potential.   
     
     
         4 . The apparatus of  claim 2 , wherein:
 the first voltage node of the primary side circuit exhibits a single ended alternating current (AC) voltage potential with respect to the reference potential;   the apparatus further includes a switching circuit including an input terminal coupled to the junction node and an output terminal, which pulses in response to the AC potential at the input terminal; and   the output providing the first modified sensed voltage to the processing circuit is a single ended pulsed voltage taken from the output terminal of the switching circuit with respect to the reference potential.   
     
     
         5 . The apparatus of  claim 2 , wherein:
 first and second voltage nodes of the primary side circuit produce a differential voltage; the plurality of series-coupled resistors includes first and second pluralities of series-coupled resistors;   the first plurality of series-coupled resistors are connected at one end to the first voltage node of the primary side circuit, and are connected at an opposite end to a first junction node; and   the second plurality of series-coupled resistors are connected at one end to the second voltage node of the primary side circuit, and are connected at an opposite end to a second junction node.   
     
     
         6 . An apparatus, comprising:
 a primary side circuit including one or more input terminals for operative connection to a source of power;   a secondary side circuit including at least one processing circuit; and   a monitoring circuit receiving a first sensed voltage from one of the input terminals of the primary side circuit, traversing an isolation boundary between the primary side circuit and the secondary side circuit while adhering to at least a safety-extra-low-voltage (SELV) specification, and providing a first modified sensed voltage to the processing circuit, wherein the monitoring circuit does not bridge any isolation circuit.   
     
     
         7 . An apparatus, comprising:
 at least one primary side circuit including one or more input terminals for operative connection to a source of power;   at least one secondary side circuit including at least one processing circuit;   a boundary providing isolation between the at least one primary side circuit and said at least one secondary side circuit, where the boundary adheres to at least a safety-extra-low-voltage (SELV) specification; and   at least one monitoring circuit receiving a first sensed voltage from one of the input terminals of the primary side circuit, traversing the boundary while adhering to the SELV specification, and providing a first modified sensed voltage to the processing circuit of the secondary side circuit,   wherein the monitoring circuit does not bridge any isolation circuit.