| 摘要 |
<p>A tristate circuit for driving three signal levels to a pin of a device-under-test is disclosed. The tristate circuit includes a driver having an output at a first signal level and adapted for coupling to the pin. A first switching unit couples to the output and responds to a programmed signal. The first switching unit operates to selectively alter the first signal level to a second signal level. A second switching unit connects serially to the first switch. The second switching unit responds to a second programmed signal and operates to cooperate with the first switch to alter the second signal level to a third signal level.</p> |
