Basic-Scan ATPG
full-scan, combinational-only ATPG tool.
To get high test coverage, the sequential elements need to be scan elements.
Combinational ROMs can be used to gain coverage of circuitry in their shadows in this mode.
Fast-Sequential ATPG
Fast-Sequential ATPG provides limited support for partial-scan designs.
In this mode, multiple capture procedures are allowed between scan load and scan unload, allowing data to be propagated through nonscan sequential elements in the design such as functional latches, non-scan flops, and RAMs and ROMs.
However, all clock and reset signals to these nonscan elements must still be directly controllable at the primary inputs of the device.
Full-Sequential ATPG
Full-Sequential ATPG, like Fast-Sequential ATPG, supports multiple capture cycles between scan load and unload, thus increasing test coverage in partial-scan designs.
Clock and reset signals to the nonscan elements do not need to be controllable at the primary inputs; and there is no specific limit on the number of capture cycles used between scan load and unload.