| 摘要 |
PURPOSE: A data output buffer is provided to selectively generate an output signal of a relatively less swing width and an output signal of a relatively more swing width, which are obtained via an open-drain output buffer. CONSTITUTION: A pull-up transistor(Q) is connected between a power supply voltage(VDD) and a node(N1), and is controlled by a pull-up controller. The pull-up controller receives an output level control signal(L) and a data signal(/D) to control the pull-up transistor(Q). The pull-up controller comprises three serially-connected inverters(INV1, INV2, INV3) and a NAND gate(NAND). The inverters are designed so as to have escalating drive capacity. A plurality of pull-down transistors(Q1-Qn) are connected in parallel with the node(N1) and a ground voltage(Vss), and are controlled in common by the data signal(/D).
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