| 摘要 |
PURPOSE:To use a scan system to check the inside of a circuit and also set logical values of output terminals in common by providing a switching circuit for a normal operation signal and a test signal and connecting scan latch outputs to test signal inputs of the switching circuit one to one. CONSTITUTION:When a test mode is entered, NOR circuits 1c-1, 2c-1,..., for example, are closed in switching circuits 1c, 2c,... to inhibit signal buses 1b, 2b,... for normal operation, but NOR circuits 1c-2, 2c-2,... are driven, so signals from scan latches 1, 2... can be sent out directly to an LSI output pin 10 through test signal buses 1a, 2a,... Therefore, a specific address is specified by conventional scan-in operation to set an optional logical value to output pins. Consequently, a check on a connection between LSIs is made based on a normal scan-in/out. |
