Integrated Half-Bridge Power Circuit

Abstract

A down converter includes an integrated circuit, which includes a control FET (CF) and a synchronous rectifier FET (SF). The control FET is a lateral double-diffused (LDMOS) FET, and the conductivity-type of the LDMOS FET and the conductivity-type of the substrate are of the same type.

Description

BACKGROUND OF THE INVENTIONField of the Invention[0001]The present invention relates generally to integrated power conversion circuits using a half bridge, and particularly, to integrated power-transistors for a down-converter power supply having improved switching characteristics.SUMMARY OF THE INVENTION[0002]Power-converters are often used in power supplies, power amplifiers and motor drives. Down converters, including Buck converters are often used to convert an input voltage to a lower voltage for supplying power to a load, such as a microprocessor. These microprocessors have applicability in personal computers (PC) as well as other electronic devices. In PC applications, the input voltage to the converter is on the order of 12 V, and the required output is on the order of approximately 1.4 V, or a factor of about ten in step-down. Moreover, the required output currents of these converters are increasing to above 50 A, further adding to the design considerations of these circuit...

AI Technical Summary

Benefits of technology

[0004]The losses associated with the on-and-off switching of down converters are beneficially minimized as much as possible. This has certain benefits, such as improving the battery life within the PC and reduction of the heat-dissipation. Conversion loss in MOSFET's is determined partly by resistance and partly by the figure of merit of the device, which is proportional to the on resistance, Ron, and the gate-to-drain charge, Qgd.

[0006]As will become clearer as the present description continues, the on-resistance and the gate-to-drain charge are improved via exemplary embodiments described herein. Other benefits of the embodiments are reduced parasitics, an option for integration of interface circuitry (for better control of the power-device switching) and a reduced production cost.

Problems solved by technology

For example, as the demand for faster switching frequencies increases, parasitic effects in such devices can have a deleterious impact on the ability of the CF and SF to meet these demands.

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