signal which also may be derived from t duty that closes switch 260 at this point a voltage representative of i lpeak est is present at node 250 thus by discharging capacitor 220 at a known rate and then interrupting the discharge at a point in time proportional to the switching period of the voltage regulator an estimate of peak current threshold i lpeak est may be obtained in the form of a voltage remaining across capacitor 220 as noted above this value may be used as a threshold value that determines when to turn the regulator 39 s switching element on or off if desired additional processing may be performed on the i lpeak est signal to obtain a particular transfer characteristic for system 100 this may be accomplished by adding transfer function circuit 120 for example if an average of the peak inductor current i lpeak avg is desired the transfer function circuit 120 shown in fig3 may be used as shown in fig3 transfer function circuit 120 may include capacitor 270 and resistor 280 when switch 260 is closed capacitor 270 and resistor 280 become electrically active and form a capacitor divider arrangement with capacitor 220 this causes the voltage difference between node 250 and node 290 to be distributed across capacitors 220 and 270 a fraction of the voltage at node 250 representing a time sample of i lpeak est is transferred to node 290 and combined with a pre existing voltage obtained from previous samples in this manner the value of i lpeak.