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:
Oct. 01, 1996
Filed:
Aug. 31, 1995
Keith M Wellnitz, Chandler, AZ (US);
Randall T Wollschlager, Chandler, AZ (US);
John Hargedon, Norwood, MA (US);
Motorola, Inc., Schaumburg, IL (US);
Abstract
A clamp circuit (50) for protecting a MOSFET (52) from destructive voltages includes a clamping element (56), a Zener diode (64), two current mirrors (66 and 62), a current switch (58), a reference current source (68), and a voltage detector (72). When a drain voltage of the MOSFET (52) rises above a clamping voltage of the clamp circuit (50), a clamping current exceeding a current in the current switch (58) flows through the clamping element (56) and activates the MOSFET (52). During the activation, the two current mirrors (66 and 62) generate an output current exceeding a reference current in the reference current source (68) and raise a voltage at an input terminal of the voltage detector (72). The voltage detector (72) generates a signal indicating the activation of the clamp circuit (50), thereby indicating that the clamp circuit (50) and its inductive load (74) are intact.