System and method for power stage current-sense accuracy improvement in a power system

A method, comprising:

• receiving, by a power control module of a power system, a current level signal;
• providing, by the power control module, a pulse-width modulation (PWM) signal in response to the current level signal;
• receiving, by a driver circuit of a power stage of the power system, the PWM signal, wherein the power stage includes a switching power converter having a high-side switch and a low-side switch;
• driving, by the driver circuit, the switching power converter based upon the PWM signal;
• detecting, by a current sensing circuit of the power stage, a low-side current level on the low-side switch;
• providing, by the current sensing circuit, the current level signal, wherein the current level signal includes the low-side current level;
• turning on the low-side switch at a first time;
• and
• estimating the first low-side current level at the first time, wherein in estimating the low-side current level, the method further comprises:
• detecting a second low-side current level at a second time while the low-side switch is turned on, the second time being a first duration of time after the first time;
• detecting a third low-side current level at a third time while the low-side switch is turned on, wherein the third time is a second duration of time after the second time, and wherein the first low-side current level is estimated based upon the second and third low-side current levels;
• determining a current difference between the second low-side current level and the third low-side current level;
• and
• dividing the current difference by a second duration of time between the second time and the third time;
• wherein the first low-side current level is estimated as:
• I1=(k×ΔI)+I2, where I1 is the estimated first low-side current level, I2 is the second low-side current level, ΔI is the current difference, and:
• k=T1/T2, where T1 is the first duration of time, and T2 is the second duration of time.

A power stage comprising:

• a switching power converter having a high-side switch and a low-side switch;
• a driver circuit configured to receive a pulse-width modulated (PWM) signal and to drive the switching power converter based upon the PWM signal;
• and
• a current sensing circuit configured to detect a low-side current level on the low-side switch, and to provide the current level signal, wherein the current level signal includes the low-side current level;
• wherein the power stage is configured turn on the low-side switch at a first time, and to estimate a first low-side current level at the first time, wherein in estimating the first low-side current level, the power stage is further configured to detect a second low-side current level at a second time while the low-side switch is turned on, the second time being a first duration of time after the first time, and to detect a third low-side current level at a third time while the low-side switch is turned on, wherein the third time is a second duration of time after the second time, wherein the first low-side current level is estimated based upon the second and third low-side current levels, to determine a current difference between the second low-side current level and the third low-side current level, and to divide the current difference by the second duration of time;
• wherein the first low-side current level is estimated as:
• I1=(k×ΔI)+I2, where I1 is the estimated first low-side current level, I2 is the second low-side current level, ΔI is the current difference, and:
• k=T1/T2, where T1 is the first duration of time, and T2 is the second duration of time.