| 摘要 |
<p>A circuit for parametric testing of I/O's including bidirectionals includes logic (100) which ties the I/O's into a single test chain. A pulse is applied moved down the chain to test the switching levels of the input buffers (132, 134, 142, 146) and the output buffers (136, 138, 144, 148). The circuit features the ability to program the bidirectionals (192-194, 196-198) as either inputs (test mode 1) or outputs (test mode 2) and so allows for its input and output buffers to be tested. The test mode can be selected simply by writing to an externally accessed data register.</p> |
