Apparatus and method for measuring load current with high resolution

An apparatus for measuring a load current provided to a load of a switching converter, the apparatus comprising:

• time extension circuitry configured to generate an extension signal that is activated during a time proportional to an on-time of at least one power switch of the switching converter;
• logic circuitry configured to generate a first control signal based on the on-time in response to a mode signal indicating a first mode, and the logic circuitry configured to generate the first control signal based on the extension signal in response to the mode signal indicating a second mode;
• switch circuitry configured to receive a first reference voltage defining a peak of an inductor current passing through an inductor of the switching converter and to generate a pulse based on the first control signal;
• a filter configured to generate an output signal by filtering the pulse;
• and
• a first comparator configured to generate the mode signal based on a voltage of the output signal and a second reference voltage,
• wherein the logic circuitry is configured to be in the second mode based on the mode signal in response to a value of the load current being less than a first threshold value.