| 摘要 |
An output driver circuit 18 is provided having an operating mode in which the output signal has a variable level dependent upon an input signal and a clamping mode in which the output signal is clamped to a fixed level. The output driver circuit includes a control circuit 20 and an output buffer 22 . The output buffer is formed of high strength, high current transistors 24, 26 which also tend to suffer high leakage. In the clamping mode, the power supply to the output buffer 22 is isolated, but the control circuit 20 serves to supply a control signal on line 36 to at least one transistor 26 within the output buffer 22 which is controlled to remain conductive and accordingly serve as a clamping transistor which clamps the output from the output buffer 22 to a fixed level.
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