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Selecting a Power Supply Configuration
Selecting a Current-Sense Resistor Value
C A U T I O N
Selecting a Load Fuse
C A U T I O N
E6198B Switch/Load Unit User Manual
Each channel connects to the power bus via a Form C SPDT
(single pole, double throw) relay. This relay has a NO
(normally-open) and a NC (normally-closed) terminal. Each NO
terminal is connected to a pin on J4-J7, and each NC terminal is
connected to a pin on J8-J11. Each pin on J4-J11 can be
connected to any of the four power bus lines on J12 via jumper
wires. See
Figure
5-43.
The terminal block jumper lets you conveniently connect
pull-up or pull-down voltages to the various inputs. You can also
terminate a UUT load at a different voltage than ground. For
example, you can connect the channel to +12 volts on one side,
and +5 volts on the other.
The factory default is to provide two jumper combs, one that
ties all the pins on J4-J7 (NO) together and one that ties all the
pins on J8-J11 (NC) together. The NO pins are jumpered to
power bus 2, and the NC pins are jumpered to power bus 1. The
jumper combs for J4-Jll can be easily cut to provide bus or pin
isolation between the various input/power bus connections.
The card comes factory loaded with a three watt, 0.05 , 0.1%
sense resistor already installed. If lower value currents are
being measured, requiring a larger resistance value to make the
sense voltage readable, then replace the sense resistor with a
four-wire resistor of higher value. The N9377A provides a
footprint for another current sense element so that you can
replace the factory provided resistor with one selected for your
specific UUT.
Be sure to size the power dissipation of the sense resistor large
enough to handle the expected current of the load.
The load fuses used are IEC 5x20 millimeter, 5-amp slow-blow.
These fuses may be replaced by fuses with a higher value, but
not to exceed 8 amps.
The maximum fuse rating must not exceed an I
Using Load Cards and Loads
2
T value of 102-126.
5
*
5-65
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