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. 17, 1998
Filed:
Mar. 21, 1997
Timothy A Phillips, Cranston, RI (US);
Cherry Semiconductor Corporation, East Greenwich, RI (US);
Abstract
A current limit circuit for preventing voltage overshoot in a driver circuit. A diode is coupled to the output terminal of the driver circuit. The diode's junction capacitance is utilized to reduce a current limit threshold in order to control the rate of change of the output voltage at the output terminal. A bias control circuit regulates a pass transistor to prevent load current provided by the driver circuit from exceeding the current limit threshold. The cathode of the diode is coupled to the output terminal so that the voltage at the cathode of the diode is responsive to the output voltage of the driver terminal. The base of a transistor is coupled to the anode of the diode so that the transistor conducts current at its collector when there is a sufficiently large rate of change in the output voltage. The collector current of the transistor reduces a reference current applied to a current mirror. The current mirror is coupled to a bias control circuit so that when the reference current is reduced, the current limit threshold of the driver circuit is also reduced. The diode, transistor, current mirror, and bias control circuit prevent overshoots by reducing the current limit threshold when a sufficiently large rate of change in the output voltage is detected, which prevents the pass transistor from overdriving the output node.