Edge749
TEST AND MEASUREMENT PRODUCTS
Circuit Description
(continued)
Driver Output Protection
In a functional testing environment, where a resistor is
added in series with the driver output (to create a 50Ω
output impedance), the Edge749 can withstand a short
to any legal DUT voltage for an indefinite amount of time.
In a low impedance application with no additional output
series resistance, care must be exercised and systems
should be designed to check for this condition and tristate
the driver if a short is detected.
Receiver Functionality
Edge749 supports programmable thresholds per
channel. There are no shared lines between comparators.
THRESHOLD is a high input impedance analog input
which defines a logical “1” and “0” at the DUT (see
Figure 4). If the DUT voltage is more positive than
THRESHOLD, DATA OUT will be high. With DUT lower
than THRESHOLD, DATA OUT will be low.
+
DATA OUT
–
DUT
THRESHOLD
THRESHOLD
DUT
DATA OUT
Tpd
Figure 4. Receiver Functionality
Revision 3 / October 21, 2002
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