Digital windowing current-mode controller for a DC-DC converter

摘要

A current-mode controlled power converter (1) comprises a controllable switch (S3) which is coupled to an inductor (L1) to obtain a periodical current (I1) through the inductor (L1). A current feedback loop (2, 3, 4, 5) generates a current-error signal (CE) which is a difference between a set current level (SC) and a level of a sensed current (SE) in the power converter (1). A driver (9) for switches off the controllable switch (S3) when the current error signal (CE) indicates that the level of the sensed current (SE) has reached the set current level (SC). A voltage feedback loop (10, 3, 7, 8, 5) influences the set current level (SC) in response to a level of an output voltage (Vout) of the power converter (1). The voltage feedback loop (10, 3, 7, 8, 5) comprises: a window circuit (10) to detect whether the output voltage (Vout) is (i) within a first window (WS) around a nominal value (Vr), (ii) outside the first window (WS) but within a second window (WL), larger than the first window (WS), (iii) outside the second window (WL). A controller (3) is coupled to the window circuit (10) to determine an adaptation of the set current level (SC), wherein the adaptation is larger when the output voltage (Vout) detected is outside the second window (WL) than when the output voltage (Vout) detected is within the second window (WL) but outside the first window (WS).

主权项

1. A current-mode controlled power converter comprising:
a controllable switch configured to be coupled to an inductor, a current feedback loop configured to generate a current-error signal determined by a difference between a set current level and a sensed current level of current in said inductor, a driver circuit configured to switch off the controllable switch when the current error signal indicates that the sensed current level has reached the set current level, and a voltage feedback loop configured to adjust the set current level in response to a level of an output voltage of the power converter, wherein the voltage feedback loop comprises:
a window comparator circuit configured to compare the output voltage to a plurality of reference voltages defining windows and generate: a first indication if the output voltage is within a first window around a nominal level, a second indication if the output voltage is outside the first window but within a second window that is larger than the first window, and a third indication if the output voltage is outside the second window, anda controller operative responsive to the first, second and third indications to generate the set current level as a function of an adaptive value, wherein the adaptive value has first level in response to the first indication, a second level greater than the first level in response to the second indication and a third level greater than the second level in response to the third indication;wherein the controller comprises a PI regulator operative to output the adaptive value comprising a proportional part and an integrating part, and wherein the proportional part and the integrating part each include first, second and third levels, the set-current level being dependent on a combination of both the proportional part and the integrating part.