Load current measurement

A metering circuit, comprising:

• scaling circuitry having a status input and a reference output, the status input adapted to be coupled to a DC-DC converter, and the scaling circuitry configured to provide a reference current at the reference output, in which the reference current is a first fraction of a peak current through an inductor of the DC-DC converter;
• a current source having a reference input and a current output, the reference input coupled to the reference output, and the current source configured to provide a fractional current at the current output, in which the fractional current is a second fraction of the reference current;
• a capacitor;
• switching circuitry coupled between the current output and the capacitor, the switching circuitry configured to control a flow of the fractional current from the current output to the capacitor;
• and
• a comparator having a comparator input and a comparator output, the comparator input coupled to the capacitor, and the comparator configured to indicate at the comparator output whether a voltage at the capacitor exceeds a threshold voltage.

A metering circuit, comprising:

• a current mirror adapted to be coupled to a DC-DC converter, the current mirror having a reference output, and the current mirror configured to provide a reference current at the reference output, in which the reference current is a first fraction of a peak current through an inductor of the DC-DC converter;
• a first current source having a first reference input and a first current output, the first reference input coupled to the reference output, and the first current source configured to provide a first fractional current at the first current output, in which the first fractional current is a second fraction of the reference current;
• a second current source having a second reference input and a second current output, the second reference input coupled to the reference output, and the second current source configured to provide a second fractional current at the second current output, in which the second fractional current is the second fraction of the reference current;
• a capacitor;
• switching circuitry coupled between the first current output and the capacitor, and coupled between the second current output and the capacitor, the switching circuitry configured to control a flow of:
• the first fractional current from the first current output to the capacitor;
• and the second fractional current from the second current output to the capacitor;
• and
• a comparator having a comparator input and a comparator output, the comparator input coupled to the capacitor, and the comparator configured to indicate at the comparator output whether a voltage at the capacitor exceeds a threshold voltage.