GR740-UM-DS, Nov 2017, Version 1.7
441
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GR740
39.5
AC characteristics
39.5.1 Test conditions
For the SDRAM, Ethernet and PCI interfaces, timing is tested using a impedance matched transmis-
sion line setup. The propagation delays in the test fixture is calibrated out as part of the test procedure.
The interfaces are tested with the pad drive strength set to maximum (the default, power-up setting)
unless noted otherwise. Interface timing measurement (setup, hold, and clock-to-out) are done with
reference to inputs or outputs entering or leaving the limits in table 578.
It is up to the end user to translate the timing data to data relevant for the system. An IBIS model of
the drivers can be provided to aid in this process.
39.5.2 Clocks
Table 579 summarizes required/recommended conditions for some of the design input clocks that
connect to on-chip PLLs. For the remaining clocks please see the interface-specific timing in the sub-
sections below
Table 578.
Output thresholds for AC parameter tests
Parameter
Symbol
Value
Unit
High output threshold
for AC parameter tests
V
OH,ACtest
VDIG33-0.4
V
Low output threshold
for AC parameter tests
V
OL,ACtest
0.4
V
Figure 55.
Test setup for LVCMOS outputs (1), LVCMOS inputs (2), LVDS outputs (3) and LVDS inputs (4)
DUT pin (driving)
ATE
Z0=50 ohm +/- 20%
100-300 mm
10-20 pF
+
-
DUT pin (receiving)
ATE
Z0=50 ohm +/- 20%
100-300 mm
50R
DUT diff pins (driving)
ATE
Z0_diff=100 ohm +/- 20%
100-300 mm
+
-
100R
DUT diff pins (receiving)
ATE
Z0_diff=100 ohm +/- 20%
100-300 mm
50R
50R