When connecting your DUT power pins to the tester power
supplies, several basic concepts should always be applied (or at least
considered). Here are some important considerations:
Power and Sense
The
DUT power supplies inside of the test system
provide programmable Vdd at the DUT board, as well as the sense lines
for each
supply. The sense lines are joined in
surface etch on the DUT board at the supply block and should be severed
at this
point to allow connection right at the device power pin(s). This is
crucial for
effective Iddq measurements. Be sure to connect the Power supply minus
to
Ground on the DUT board. If you do not
comply, your ground may "float" relative to the ground inside the
tester, and thereby yield inaccurate parametric measurements and supply
performance.
Bypass Capacitors
You will need .01 and/or .1 uf bypass capacitors right at
the power pins of the DUT chip socket for a local reservoir of power.
Keep the leads as short as possible, and No Electrolytics! The
farther your DUT is from the Power Supply, the more important are these
capacitors.
Continuity
You may wish to create a SET file that includes the power and ground
pins, solely for the purpose of checking continuity. These pins are
typically connected directly to power and ground and do not get
assigned to tester channels and so are excluded from continuity tests.
Note: This applies only when power and ground pins are also connected
to tester channels; custom DUT boards that do not connect power and
ground pins to tester channels are N/A for this issue. Also, you may
need to remove Power and Ground jumpers to give the ETS channel control
over the DUT pin, just for the continuity test. For this reason, many
forego continuity tests on Power and Ground pins.
#E20