| Popis: |
Many analog and mixed signal devices have very few or no digital pins. In spite of this, these products can be highly complex internally, including significant digital content. They may contain various sensors and control circuitry, which react to a variety of conditions to control the power profile of the part and its environment. These factors can make these devices very challenging to test. They require complex circuitry, comprising digital control for setting test modes (stimulus) and for enabling observation features (response); these features are needed for each of the different product functions in order to characterize and screen them. For many applications, dedicated test pins are unacceptable because of manufacturing costs. Reducing the number of pins means fewer ATE instruments are required and the overall die and package footprint is minimized. Additionally, some analog and mixed signal devices may not have any digital IO functionality at all. And, adding digital capability at the IO for test purposes may not be an option. Further, for clocking during debug and during test entry, relying on internal oscillators may not be a good choice. The paper presents a unique one-pin input, for purposes of test that can carry a P1687.1-like protocol. It will show how the single-pin interface was implemented in silicon, including actual test results. The approach presented demonstrates how a single analog input can be used to provide clock and data information on a single pin. |
