| 摘要 |
An output buffer circuit includes a pull-up section for connecting therethrough a source line Vcc and an impedance control terminal, a comparator for comparing the potential of the impedance control terminal against a potential of Vcc/2, an UP/DOWN counter for up- and down-counting clock pulses of a clock signal based on the result of the comparison, a D/A converter for converting an output from the UP/DOWN counter, an output section, connected between the source line Vcc and an output terminal, for receiving an input data signal to output an output data signal based on the input data signal. The output from the D/A converter controls both the ON-resistances of the pull-up section and the output section. The output impedance of the output buffer circuit is controlled based on the resistance of an external resistor connected between the impedance control terminal and ground.
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