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:
Nov. 19, 1996
Filed:
Apr. 22, 1994
Andrew Marshall, Dallas, TX (US);
Stephen C Kwan, Plano, TX (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
A circuit (10) and method for detecting a fault in a recirculation diode (13) in a switched power supply. The power supply has a switching transistor (12) that is turned on and off by a power supply control device (31), switchably applying a supply voltage (15) to an output (14). The recirculation diode (13) is connected between the output (14) and a reference potential (16). The circuit includes a sense resistor (11) in series between the supply voltage (15) and the switching transistor (12). A biasing element (25) is connected to clamp a current control element of the switching transistor (12) to the reference potential (16) when the switching transistor (12) is switched off so that a fault in the recirculation diode (13) results in a current flowing in the switching transistor (12). An amplifier (33) is connected across the sense resistor (11). The amplifier (33) has a variable gain (35) controlled by the power supply control device (31), a normal gain when the switching transistor (12) is turned on, but an increased gain when the switching transistor (12) would be normally turned off, to measure the current, if any, in the switching transistor (12) resulting from any faults in the recirculation diode (13). A control transistor (27) controlled by the power supply control device (31) is connected to switchably connect a voltage (30) to the current control element of the switching transistor (12).