Common I/O Bypass
Original Publication Date: 1985-Mar-01
Included in the Prior Art Database: 2005-Feb-18
Controlling electrical noise during LSI logic testing is normally accomplished by keeping off-chip drivers (OCDS) at an inhibited state as test conditions are being applied to the appropriate device inputs. All internal logic states are thus allowed to stabilize without excessive switching of the off-chip drivers, which can then be enabled in a controlled environment to allow output measurements to be taken. Common I/O (CIO) pins do not allow for such a procedure, however, because the very act of enabling the OCD transfers control of CIO receivers from the tester voltage (i.e., '1' level) to the OCD voltage change, thereby allowing excessive switching at the OCDs which have been enabled.