| 摘要 |
PURPOSE: A tri-state output buffer is provided to be capable of preventing a crowbar current from flowing at a tri-state operation. CONSTITUTION: Tri-state enable signals(TRST, /TRST) are applied to gates of PMOS and NMOS transistors(PM21, NM21), respectively. The tri-state enable signal(TRST) is applied in common to the control terminals of transfer gates(TR21, TR22), and to inverted control terminals of the transfer gates(TR21, TR22) via an inverter(I21). An output terminal(Dout) is connected to a drain common connection point of PMOS and NMOS transistors(PM22, NM22). The output terminal is connected to a drain of the PMOS transistor(PM21), whose source is connected to a power supply terminal(VDD), via the transfer gate(TR21). The drain common connection point is connected to the gate of a PMOS transistor, whose source is connected to the power supply terminal(VDD), via inverters(I22, I23). A drain of the NMOS transistor(NM21), whose source is grounded, is connected to the output terminal via the transfer gate(TR22). The drain of the NMOS transistor(NM21) is connected to a gate of an NMOS transistor(NM22) via inverters(I24, I25).
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