Note

Application Note 15
4 Un-Powered Testing (MDA)
The following test method was developed using an Agilent* 3070 Series II In-circuit tester in an
un-powered mode. The technique and results should be similar when using test equipment with
similar capabilities as described below. (Please note that Agilent was formerly known as Hewlett
Packard* or HP).
The typical Intel
®
Socket Test Technology switch pair is shown in Figure 4-1 using the G Bus to
short circuit VCCP to GND and potentially eliminates the charge/discharge time caused by the
large capacitance present on the board when testing the High Side switch. The intent is to make the
over all test as fast and reliable as possible.
Each switch is tested by connecting the A Bus to the Hcontrol or Lcontrol, the S and I Buses to the
Signal, and the L Bus to GND. The A Bus is set to 1.2V to ensure a positive turn on of the switch.
The S Bus is set to 600mV for the High and Low Side switch. The S Bus uses a 500 series
resistance for both the High and Low Side switch.
Table 4-1. Test Equipment Technique
Bus Description
S Bus Primary Source. Provides -10.0V to +10.0V (VDC) by connecting the high side to the Device
under Test (DUT) through a 500 series resistance. The low side connects itself automatically to
digital and switched analog GND.
A Bus Auxiliary Source. Provides -10.0V to +10.0V (VDC) by connecting the high side to the DUT and
the low side automatically to digital and switched analog GND.
I Bus The high side of a DC voltmeter connected to the DUT.
L Bus The low side of a DC voltmeter connected to digital and switched analog GND unless otherwise
specified through software.
G Bus Guard Bus. Used to break parallel impedance paths. In this case, it connects VCCP and GND to
keep them at the same potential.
Figure 4-1. Typical Switch Pair Configuration
GND
VCCP
Signal
Board VCCP- GND
Capacitance
Hcontrol
Lcontrol
G Bus
Connection