2 Note

Theory
307507-002 9
2 Theory
The Intel
®
Socket Test Technology LGA775 socket test chip consists of an array of
switch pairs. Each switch pair, together with a control signal, can be used to test one
signal, one power, and one ground. The control signal enables the ON/OFF condition
of each switch. Testing is accomplished by checking the ON and OFF condition of
each switch. There are fewer signals than power and ground electrical socket
connections. To compensate there are four pairs of Hcontrol and Lcontrol signals that
allow the multiplexing of signals between power and ground electrical socket
connections. Signal multiplexing provides testing for as many power and grounds as
possible. Testing of resistors that are also on the test chip help to provide some
additional open coverage not provided by the switch pairs.
The control signals are pulled to ground with a resistor to keep the switches in an OFF
state when a powered test method is being used on an ICT.