Voltage and current protection in isolated switched-mode power converters with secondary-side rectified voltage sensing

An electronic system comprising:

• an input power source;
• an output load;
• a switched-mode power converter using an isolated topology for converting power from the input power source into power for the output load, the switched-mode power converter comprising:
• a power stage coupled to the input source and comprising one or more power switches;
• a transformer comprising a primary winding coupled to the power stage, and a secondary winding;
• a rectifier circuit coupled to the secondary winding and configured to provide a first rectified voltage at a first rectified voltage node;
• a filter circuit interposed between the first rectified voltage node and an output of the switched-mode power converter, and configured to filter the first rectified voltage, thereby providing a filtered voltage at the output;
• and
• a secondary-side controller configured to:
• generate control signals to control the power stage during a steady-state operational mode, so as to regulate the filtered voltage at the output;
• sense the first rectified voltage;
• detect, during the steady-state operational mode, a fault condition within the switched-mode power converter based upon the sensed first rectified voltage;
• and
• generate a fault indication responsive to said detection;
• and
• a secondary-side system manager configured to:
• input the fault indication;
• and
• responsive to determining that the fault indication indicates an unsafe operating condition or a condition likely to damage the electronic system, shut down the switched-mode power converter.

A method within an isolated switched-mode power converter for converting power from an input source into power for an output load, wherein the power converter comprises a primary side including a power stage coupled to the input source and comprising one or more power switches, a transformer comprising a primary winding coupled to the power stage and a secondary winding, and a secondary side including a rectifier circuit coupled to the secondary winding and configured to provide a first rectified voltage at a first rectified voltage node, a filter circuit interposed between the first rectified voltage node and an output of the switched-mode power converter, the method comprising:

• generating control signals to control the power stage during a steady-state operational mode, so as to regulate the filtered voltage at the output;
• sensing the first rectified voltage;
• detecting, during the steady-state operational mode, a fault condition of the primary side, based upon the first rectified voltage sensed on the secondary side;
• and
• generating a fault indication and/or modifying operation of the switched-mode power converter responsive to said detecting.