Note

Application Note 9
2 Theory
The Intel
®
Socket Test Technology LGA771 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.