| 摘要 |
PROBLEM TO BE SOLVED: To provide a test circuit having an effect for suppressing the cost of LSI production by eliminating a LSI test pin unnecessary for a normal operation. SOLUTION: When a shift register 7 and a control circuit 9 are reset by resetting or a control input 6, a test mode setting input pin 4 is connected to the shift register 7 by a selector 10. Then, a test mode signal is input by the test mode setting input pin 4, and its state is stored by the shift register 7. When a preset clock pulse number is achieved, an output 12 of the control circuit 9 changes for switching the selector 10 to connect the test mode setting input pin 4 to a connecting signal 14 for a circuit used for other use. An output of the shift register 7 is decoded by a decoder 8 and becomes a test mode output 11.
|
