High-side transistor driver for power converters

Abstract

The high-side transistor driver according to the present invention includes a high-side transistor, a low-side transistor, a drive-buffer and an on / off transistor. When the low-side transistor is turned on, a charge-pump diode and a bootstrap capacitor produce a floating voltage. The drive-buffer will propagate the floating voltage to switch on the high-side transistor. The on / off transistor is used to switch the drive-buffer. The high-side transistor drive further includes a speed-up circuit. The speed-up circuit has a capacitive coupling for generating a differential signal. When the on / off transistor is turned off, the speed-up circuit accelerates the charge-up of the parasitic capacitor of the on / off transistor, thus accelerating high-side transistor switching.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a high-side transistor driver, and more particularly to a driver circuit for driving the high-side transistor of a power converter.[0003]2. Description of the Prior Art[0004]Many modern-day power converters use bridge circuits to control a voltage source coupled to a load. Power supplies and motor drivers are common examples of such power converters.[0005]A bridge circuit normally has a pair of transistors connected in series across the voltage source, with a high-side transistor connected to the voltage source and a low-side transistor connected to the ground reference. The bridge circuit includes a common node that is connected between the high-side transistor and low-side transistor. This common node is also coupled to the load.[0006]The high-side transistor and the low-side transistor are controlled to alternately conduct. As this happens, the voltage of the common node will swing be...

AI Technical Summary

Benefits of technology

The present invention is a high-side transistor driver that can be used in high-voltage and high-speed applications. It includes a floating-ground terminal and a floating-supply terminal, which allows for the supply of a floating voltage to the driver. The driver also includes a charge-pump diode and a bootstrap capacitor connected in series, which can produce a floating voltage when the low-side transistor is turned on. An inverter is included to drive the high-side transistor, and an on / off transistor is included to turn it on and off. A speed-up circuit is also included to rapidly charge up the parasitic capacitor of the on / off transistor. The efficiency of the high-side transistor driver is improved with this invention.

Problems solved by technology

One drawback of this circuit is that it has high switching losses in high-voltage applications.

Such high-voltage transistors typically have a large parasitic capacitor, which will increase the rising-time and slow down the switching signal.

This will result in high switching losses from the high-side transistor.

Therefore, this prior-art bridge circuit is inadequate for high-voltage and high-speed applications.

The on / off transistors of these prior-art inventions cause high switching losses in high-voltage applications.

However, this technique uses a voltage doubling circuit that requires an additional switching element as well as other circuitry, thereby adding to the cost and complexity of the driving circuit.

Moreover, high frequency charging and discharging of the voltage doubling capacitor in the charge pump will result in severe noise being generated at the voltage source terminal and the ground reference terminal.

Images