BUCK-BOOST CONVERTER WITH BUCK-BOOST TRANSITION SWITCHING CONTROL

摘要

A buck-boost regulation methodology operable, in one embodiment, with a single inductor, four-switch (S1-S4) buck-boost regulator configured for DCM. Buck-boost transition switching control is operable when inductor charge time exceeds a max charge time, and inductor discharge time exceeds a max discharge time, and includes: (a) during charge transition cycles, at the end of the max charge time, if IL is less than a predetermined peak current ILMAX, switching S2 on (grounding the output side of the inductor) and S4 off, causing IL to increase (a rapid S1S2 charging current ramp), until IL reaches ILMAX, and (b) during discharge transition cycles, at the end of the max charge time, if IL is greater than zero, switching S1 off and S3 on (grounding the input side of the inductor), causing IL to increase (a rapid S3S4 IL discharging current ramp), until IL reaches zero.