Patent ID: 6763488
Filing Date: 2004-07-13
Classification: G01R

Abstract:
A scan circuit comprising:A. a functional circuit formed on the semiconductor substrate of an integrated circuit, the functional circuit including logic circuits to be tested; B. a scan path circuit formed of serially connected scan cells, the scan path circuit having leads connected to the logic circuits to carry stimulus signals to the logic circuits and to receive response signals from the logic circuits, the scan path circuit having a serial data input lead and a serial data output lead, the scan path circuit having control input leads for receiving control signals to control operation of the scan path circuit, the scan path circuit being organized in selectable, separate scan path parts, each scan path part having a serial input connected to the serial data input lead, a serial output lead selectively coupled to the serial data output lead and a separate set of control input leads; C. a test data generator circuit having control inputs and a serial data output connected to the serial data input lead of the scan path circuit; D. a test data compactor circuit having control inputs and a serial data input connected to the serial data output lead of the scan path circuit; E. a controller having control output leads connected to the control inputs of the generator circuit and to the control inputs of the compactor circuit, and coupled to the control inputs of the scan path circuit; and F. adaptor circuits coupling the control output leads of the controller to the separate sets of control input leads of the scan path circuit, the adaptor circuits including input leads receiving one set of control signals from the controller and including a set of output leads providing control signals for each scan path part, the adaptor circuits including a state machine controlling the production of the separate sets of control signals for operating the respective separate scan path parts, and the adaptor circuits including counter circuits connected to the state machine.