|
A built-in self-test (BIST) or built-in test (BIT) is a mechanism that permits a machine to test itself. Engineers design BISTs to meet requirements such as: *high reliability *lower repair cycle times or constraints such as: *limited technician accessibility *cost of testing during manufacture The main purpose of BIST is to reduce the complexity, and thereby decrease the cost and reduce reliance upon external (pattern-programmed) test equipment. BIST reduces cost in two ways: # reduces test-cycle duration # reduces the complexity of the test/probe setup, by reducing the number of I/O signals that must be driven/examined under tester control. Both lead to a reduction in hourly charges for automated test equipment (ATE) service. ==Naming== The BIST name and concept originated with the idea of including a pseudorandom number generator (PRNG) and cyclic redundancy check (CRC) on the IC. If all the registers that hold state in an IC are on one or more internal scan chains, then the function of the registers and the combinational logic between them will generate a unique CRC signature over a large enough sample of random inputs. So all an IC need do is store the expected CRC signature and test for it after a large enough sample set from the PRNG. The CRC comparison with expected signature or the actual resultant CRC signature is typically accessed via the JTAG IEEE 1149.1 standard. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Built-in self-test」の詳細全文を読む スポンサード リンク
|