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:
May. 20, 1997
Filed:
Oct. 25, 1995
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
An output buffer circuit operating normally when its supply potential is exceeded by the potential of the bus to which the buffer circuit output is connected. The circuit comprises a p-channel MOS transistor and a first and a second n-channel MOS transistor. The output node of the output buffer circuit is connected not to the p-channel MOS transistor but to the connection point between the source of the first n-channel MOS transistor and the drain of the second n-channel MOS transistor. The threshold potential of the first n-channel MOS transistor is set so that, with the output node in the high-impedance state, the first n-channel MOS transistor is turned off when the output node potential exceeds the supply potential of the output buffer circuit. This prevents the p-channel MOS transistor from getting activated or from being forward-biased between the back gate and the drain or source. Thus no leak current flows when the bus potential becomes higher than the supply potential of the output buffer circuit.