12.5 A 2MHz 12 to 100V 90% efficiency self balancing ZVS three level DC DC regulator with constant frequency AOT V2 control and 5ns ZVS turn on delay
Wide input rails (12V to 100V) are common in today's automotive and industrial systems. Miniaturized DC DC voltage regulators (VRs) which can provide a low voltage regulated output from a wide input range and deliver a few Watts, are essential in these systems. Wide input range integrated VRs, however have difficulty to simultaneously achieve high frequency (HF) operation and high power efficiency. Previous hard switching (HS) high input voltage (HV) buck regulators can only operate at a low frequency of 100s of kHz in order to limit the dominant switching power loss PSW, that occurs at the converter switching node [1,2] Low frequency operation however results in using bulky inductors of 100s of mH, significantly increasing the bill of material cost and the converter volume. Three level converters (TLCs) are effective to reduce the required inductance by doubling the frequency at the switching node and allow using lower voltage rating power transistors in HV conditions. However, the concern of large PSW in HV conditions would still limit the HS TLC converter to operate in the MHz range. Moreover, the TLC needs the voltage across its flying capacitor to be balanced at half the input voltage; otherwise power transistors could be damaged during operation. In HF HV conditions, the capability of high speed flying capacitor self balancing is even more crucial, but it is not addressed in prior 3 level DC DC regulators [3,4] This paper reports a ZVS based 3 level voltage regulator (TL VR) to remove PSW in HF and HV conditions, thereby improving the converter power efficiency. A constant frequency adaptive on time (CF AOT) V2 control is developed to offer the flying capacitor self balancing in the MHz range, ensuring reliable regulator operation with a wide input range. A body diode based floating ZVS detection is also proposed to provide nanosecond scale ZVS turn on delay and thus enable full ZVS operation in HF low duty ratio conditions.
2016 IEEE International Solid State Circuits Conference (ISSCC)