Measuring a change in voltage

A circuit for measuring a voltage drop at a node, the circuit comprising:

• an analog-to-digital converter (ADC) coupled to the node;
• a current sink coupled to the node and an input of the analog-to-digital converter, the current sink configured to be adjusted via a control signal to selectively adjust an amount of current sunk through the current sink;
• and
• a controller coupled to an output of the analog-to-digital converter and a control input of the current sink, the controller configured to:
• determine a set point for the current sink;
• sample an output of the analog-to-digital converter during the voltage drop;
• and
• compute a relative voltage drop value comprising subtracting the sampled output of the analog-to-digital converter during the voltage drop from a sampled output of the analog-to-digital converter during a steady-state condition, the current sink operating at the set point during the steady-state condition and during the voltage drop.

A system, comprising:

• a capacitor having a first node;
• an analog-to-digital converter (ADC) coupled to the first node;
• a current sink coupled to the first node and an input of the analog-to-digital converter, the current sink configured to be adjusted via a control signal to selectively adjust an amount of current sunk through the current sink;
• and
• a controller coupled to an output of the analog-to-digital converter and a control input of the current sink, the controller configured to:
• determine a set point for the current sink;
• sample an output of the analog-to-digital converter during a voltage drop at the first node;
• and
• compute a relative voltage drop value comprising subtracting the sampled output of the analog-to-digital converter during the voltage drop from a sampled output of the analog-to-digital converter during a steady-state condition, the current sink operating at the set point during the steady-state condition and during the voltage drop.