Synchronous buck-boost DC-DC conversion circuit with wide output range

Abstract

The invention discloses a synchronous buck-boost DC-DC conversion circuit with a wide output range, so that a problem of small dynamic output range in the prior art can be solved. The circuit consists of a switch power tube M1, a freewheeling power tube M2, a PMOS drive circuit, an NMOS drive circuit, a level shift circuit, an energy storage inductor L and an output filter capacitor Cout. The PMOS drive circuit and the NMOS drive circuit are respectively connected with grids of the switch power tube M1 and the freewheeling power tube M2 as well as are used for driving the M1 and the M2 to be conducted and cut off. The output of the level shift circuit is connected to a power input terminal of the NMOS drive circuit, so that the grid voltage of the freewheeling power tube M2 can be changed with differences of outputs Vouts of the buck-boost DC-DC; when the M2 is conducted, a difference value between the grid voltage and a source voltage can be always maintained to be constant. According to the invention, an output dynamic range of a converter can be effectively increased and a power supply rejection ratio output by the converter can be improved; and the synchronous buck-boost DC-DC conversion circuit can be applied to equipment employing a DC-DC switch power supply.

Description

technical field [0001] The invention belongs to the technical field of electronic circuits, and relates to an analog integrated circuit, in particular to a synchronous step-down-boost DC-DC conversion circuit with a wide output range. Background technique [0002] In the typical topology of buck-boost DC-DC, Schottky diodes are usually used as freewheeling power transistors. However, due to the large forward voltage drop of the Schottky diode, the loss generated during operation is also large, which limits the improvement of the efficiency of the converter, so the synchronous rectification technology came into being. [0003] Synchronous rectification technology uses metal oxide MOS transistors instead of Schottky diodes. Since the conduction voltage drop of freewheeling power MOS transistors is much smaller than the forward conduction voltage drop of Schottky diodes, it reduces the time required for freewheeling power transistors during operation. The resulting loss greatl...

AI Technical Summary

Problems solved by technology

However, the devices in the drive circuit usually use low-voltage technology. In order to prevent the devices in the drive circuit and the freewheeling power MOS tube from high-voltage breakdown, the output voltage must be designed within a certain range, resulting in the range of output voltage change, that is, the output dynamic range. reduced, limiting the application of the converter

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