Open drain driver having enhanced immunity to I/O ground noise

An open drain I/O driver includes an input node, an output node, a first reference node, a first transistor, and noise immunity circuitry. The first transistor has its gate coupled to the input node and its conducting path coupled in series with the output node and the first reference node. The firs...

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Bibliographic Details
Main Authors CLERGE JEAN-ROBERT, SANWO IKUO JIMMY, NEJAT MAHYAR
Format Patent
LanguageEnglish
Published 22.08.2002
Edition7
Subjects
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Summary:An open drain I/O driver includes an input node, an output node, a first reference node, a first transistor, and noise immunity circuitry. The first transistor has its gate coupled to the input node and its conducting path coupled in series with the output node and the first reference node. The first transistor operates to uncouple the output node from the first reference node in response to an input voltage applied to the input node. The noise immunity circuitry keeps the output node uncoupled from the first reference node during undershoot noise in a first reference voltage that causes the first transistor to change from an off state to an on state. The noise immunity circuitry includes second and third transistors. The second transistor has its gate coupled to the input node and its conducting path coupled in series with the conducting path of the first transistor. The third transistor is configured to keep the second transistor in an off state during the undershoot noise.
Bibliography:Application Number: US20000749704