摘要:
Circuitry (20) and an associated an method of operation provides system data (30) and scan data (32) to a latch portion (42) of a data storage element in a reduced setup time period. For each data storage element, a system data transfer gate (22) provides system data (30) to a master latch portion (42) while a scan data transfer gate (24) provides scan data (32) to the master latch portion (42). The scan data (24) and system data transfer (22) gates minimize the set-up time required for data entering the data storage element. Scan chains incorporating the data storage elements include scan data input ports and scan data output ports as well as connections between data storage elements in an associated scan chain. A controller (26) operated by a scan enable signal (38) and a system clock (40) provide control signals to the system data transfer gate (22) and the scan data transfer gate (24) to cause the gates to selectively pass data. The controller 26 serves as a multiplexor function for scan data and system data, and serves a clocking loading minimizing function to speed the data path.
摘要:
A scan chain architecture which has a controller (10), and a multiplexer (24) is used to route test data through functional units (12, 14, 16, 18, 20, and 22). The controller (10) receives as input a serial data stream from an STDI terminal and demultiplexes this data stream to one of the functional units (six functional units are illustrated in FIG. 1). Each of the functional units is considered as one scan chain and therefore FIG. 1 has six scan chains (one for each functional unit). In addition, a seventh scan chain couples all output flip-flops in each of the functional units together between an output of the MUX (24) and the STDO terminal/pin. Therefore, a serial scan of a data stream can be done through one functional unit, the multiplexer (24) and into the output flip-flops of each function unit to make testing easier to set-up. In addition, various new scan chain cells and low power methods are used herein.