Clamping current limit of a hysteretic power converter to a minimum value to ensure graceful shutdown at battery end of life

A method comprising, in a system including a power source and a power converter having an input coupled to the power source and an output for supplying electrical energy to a load:

• monitoring, with a first feedback control system, an output voltage present at the output of the power converter and regulating the output voltage at or about a predetermined regulated voltage level in a normal mode of operation of the power converter;
• monitoring, with a second feedback control subsystem, an input voltage present between the power source and the input of the power converter;
• and
• responsive to the input voltage decreasing below a predetermined minimum voltage level, causing, by the second feedback control subsystem, the power converter to operate in a protection mode of operation in order to maintain the input voltage at or about the predetermined minimum voltage level.

A mobile device comprising:

• a power source;
• a power converter having an input coupled to the power source and an output for supplying electrical energy;
• one or more components downstream of the power converter and configured to receive power from the electrical energy supplied by the power converter;
• and
• a control circuit for controlling operation of the power converter, the control circuit comprising:
• a first feedback control subsystem configured to monitor an output voltage present at the output of the power converter and regulate the output voltage at or about a predetermined regulated voltage level in a normal mode of operation of the power converter;
• and
• a second feedback control subsystem configured to:
• monitor an input voltage present between the power source and the input of the power converter;
• and
• responsive to the input voltage decreasing below a predetermined minimum voltage level, causing the power converter to operate in a protection mode of operation in order to maintain the input voltage at or about the predetermined minimum voltage level.