Current control for power converter

A controller for a power converter, comprising:

• a duty generation circuit configured to generate a pulse width modulated signal (PWM signal) that includes a compensation period;
• a current-sense circuit configured to generate a current-sense signal corresponding to a current through a transistor of the power converter;
• a current-sense comparator configured to generate a first trigger signal when the current-sense signal equals a first threshold and a second trigger signal when the current-sense signal equals a second threshold;
• a counter that is configured by the PWM signal to begin timing at a start of the ON portion of the PWM signal and to output a first ON-time upon receiving the first trigger signal and a second ON-time upon receiving the second trigger signal;
• and
• a subtractor to compute the compensation period based on a difference between the first ON-time and the second ON-time.

A controller for a power converter, the controller including circuitry configured to:

• detect a pulse width modulated (PWM) signal including PWM cycles, each PWM cycle including an ON portion and an OFF portion;
• detect, during the ON portion, a current-sense signal corresponding to a load current, the current-sense signal increasing during the ON portion;
• determine a compensation time related to an offset between a start time of the ON portion of the PWM cycle and a time at which the current-sense signal increases above zero;
• determine a half-peak current-sense voltage by sampling the current-sense signal at a time that is adjusted by the compensation time;
• detect, during the OFF portion, a drain voltage corresponding to the load current, the drain voltage decreasing during the OFF portion;
• determine a discharge time related to a period between a start time of the OFF portion of the PWM cycle and a time at which the drain voltage decreases to zero;
• determine a conduction time of a load based on a time of the ON portion, the discharge time, and the compensation time;
• multiply the half-peak current-sense voltage and the conduction time to determine a load-level;
• compare the load-level to a reference level;
• adjust a duty cycle of the PWM signal;
• and
• apply the PWM signal to the power converter.