Power transistor driving circuits and methods for switching mode power supplies

摘要

A power supply controller is provided for providing a drive current to a control terminal of a power transistor in three time intervals. The controller includes control circuits configured to control the drive current in multiple stages. During a first time interval, first drive current includes a current spike for turning on the power transistor in response to a start of the control signal pulse. During a second time interval, a second drive current includes a ramping current substantially proportional to a magnitude of a current through the power transistor. During a third time interval, current flow to the power transistor is at least partially turned off before an end of the control signal pulse.

主权项

1. A driver circuit, the driver circuit comprising:
a current mirror having first and second PMOS transistors; a bipolar transistor coupled to the second PMOS transistor of the current mirror to receive a first current; and a plurality of serially connected diode devices coupled between a collector and a base of the bipolar transistor; wherein the collector of the bipolar transistor is configured to provide a driving voltage according to the number of the plurality of serially-connected diode devices and the size ratio between the first and the second PMOS transistors.