| 摘要 |
A TDO output apparatus for a boundary scan architecture selectively outputs TDO of a boundary scan input/output cell. The TDO output apparatus includes: a boundary scan register wherein a third boundary scan cell generates a scan signal; a update register having first and second update cells outputting a scanning signal of the first and second boundary scan cells; a first multiplexer for selectively outputting an output enable signal and an output of the first update register according to an external test signal; a second multiplexer for selectively outputting an output data signal and an output of the second update cell; 3-state buffer for selectively outputting an output of the second multiplexer; and a selector connected between the scan cells of the first to third boundary scan cells and the shift register, for selectively outputting output signals of the first to third scan cells as TDO according to an output of the shift register.
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