The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 10, 2001
Filed:
May. 04, 1999
Giovanni Galli, Messina, IT;
STMicroelectronics S.r.l., Milan, IT;
Abstract
A protection circuit is disclosed for a bipolar power transistor for preventing the operating point thereof from leaving a useful operating area. The protection circuit includes a sense resistor connected between an input supply voltage and a collector of the bipolar power transistor; a first branch circuit, including a first diode connected to the collector of the bipolar power transistor and a first current source connected between a common output node and the first diode; a second branch circuit, including a second diode and a second current source connected between the second diode and the common output node; and a third branch circuit. A short-circuit current level of the bipolar power transistor at relatively low voltage levels of the input supply voltage is based upon current levels for the first current source and the second current source and a resistance value of the sense resistor connected to the bipolar power transistor. The protection circuit further includes a fourth circuit branch including a current mirror connected to the common output node and a third current source connected between the input supply voltage and the current mirror. A short-circuit current level of the bipolar power transistor at relatively high voltage levels of the input supply voltage is substantially equal to the current level of the third current source.