Note

Un-Powered Testing (MDA)
16 Application Note
The resistance of the switch is equal to approximately 40 in the ON state and is infinite in the OFF
state. In an isolated environment, the ON state voltage measured at the signal would be
approximately 44mV as a voltage divider exists between the 40 switch resistance and the 500
resistance of the source termination.
It has been observed that the OFF state voltage doesn’t reach the 600mV level that circuit theory
would lead one to expect. This is due to the influence of other on-board devices that cause the level
to settle at approximately 250mV.
§
Figure 4-2. Instrument Setup For Low Side Switch
GND
VCCP
Signal
Board VCCP-
GND Capacitance
Hcontrol
Lcontrol
G Bus
Connection
A Bus
+1.2V
DC DC
S Bus
+600mv
MV
I Bus
L Bus
500 ohm S Bus
Termination
1K ohm
Figure 4-3. Instrument Setup For High Side Switch
GND
VCCP
Signal
Board VCCP-
GND Capacitance
Hcontrol
Lcontrol
G Bus
Connection
A Bus
+1.2V
DC DC
S Bus
+600mv
MV
I Bus
L Bus
500 ohm S Bus
Termination
1K ohm