| 摘要 |
PURPOSE: An input/output buffer of a semiconductor integrated circuit is provided to prevent an error operation caused by being applying the source voltage greater than a supply voltage through an input/output pad. CONSTITUTION: A data input/output device includes input/output buffers(210,230) together. In the output buffer, a data output section(211) generates pull-up and pull-down signals responding to an enable signal and an output data. A pull-up driving section(215) applies the first supply voltage being a driving voltage of the input/output buffers to the input/output pads responding to the pull-up signal. A pull-down driving section(217) applies a ground voltage to the input/output pads responding to the pull-down signal. A control section of current flowing(213) prevents the current from flowing through the pull-up driving section when the input signal is applied to the input/output pads with the second supply voltage level greater relatively than the first supply voltage. A pass gate(212) buffs the stress applied to the transistor of the data output section when the input signal is applied with the second supply voltage level. The first section(214) of stress buffering buffs the stresses generated by the high voltage applied to the pass gate when the input signal is applied with the second supply voltage level. The second section(216) of stress buffering buffs the stresses generated by the high voltage applied to the pull-down driving section when the input signal is applied with the second supply voltage level. A latch-up prevention section(218) prevents the generation of a latch-up by keeping a Nwell bias of the pull-up driving section be floated, the current pass control section and the stress buffering section. A noise reduction section(219) reduces the noise applied to the input/output pads
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