Apparatus and method for interfacing a high speed scan-path with slow-speed test equipment
US6779142B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 31, 2000 |
| Grant date | Aug 17, 2004 |
| Priority date | — |
| Expiry date | Jul 13, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R31/318536
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A system for scan testing a device under test (“DUT”) in which the clock speed of the DUT differs from test equipment. A plurality of scan-flops in the DUT form a scan-wheel, which defines a closed scan path. The Data bits in the scan path are shifted through a scan-wheel controller based on the DUT clock speed, so that a different bit passes through the scan-wheel controller on each clock cycle of the DUT. Test data is only loaded by replacing the data bit as it passes through the controller. The different clock rates of the DUT and the test equipment define a scan wheel ratio, which is used to determine the number of times that the scan-wheel must rotate before all old data bits are unloaded and replaced by newly loaded bits, and which also determines when data bits passing through the controller will be unloaded and replaced.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.