Farnell TSV 70 - Performance and Applications; Series Operation; Parallel Operation; External Sensing Operation

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TYPICAL PERFORMANCE_AND APPLICATIONS.
SERIES OPERATION
SECTION V1
Units may be connected in series to provide higher
Qutput voltages. It is recommended that a protective
diode is. fitted across the output terminal of each unitt
cathode to positive terminal to prevent the supplies
becoming reverse biased under overload conditions.
diode should have a urrent rating egual to the maximum
output capability of the unit. It is recommended that
not more than three units be series connected.
PARALLEL OPERATION
Units may be connected in parallel to increase the
current capability. In order to parallel them the units
should be adjusted for equal output voltage and their
output terminals then connected in parallel. In such a
system, as output load current is increased from zero,
the un it having the highest voltage setting will conduct
until it reaches its current limit point. The unit with
the next highest voltage will then conduct until it
reaches its current limit point and so on. The V/I
characteristic of a system of three units connected in
parallel is shown in figure 2.Pl4This shows a series of
descending steps in voltage as the load current increases.
The magnitude of the step depends on how closely the
voltages can be set together. The resolution of the
fine potentiometer is approximately l0mV hence the steps
No more than
in
voltage
could
not
be
lower
than
lOmV.
EXTERNAL SENSING OPERATION
The
Units are supplied with links between the SENSE and
OUTPUT terminals. If it is required to correct for the
Voltage drop along the leads carrying current to the
load,, it is. possible to use a four terminal Conne ction.
It is not possible to correct for more than volt drop
in each lead.
Addition of lead from the sensing terminals and
output
terminals
increases
the
inductance
in
the
feedback path, which could give rise to instability at
high frequencies unless the following precautions'are
taken.
The leads from the + OUTPUT and + SENSE terminals
should be twisted together. The leads from the "
oUTPUT" and "- SENSE" terminals should be twisted
together.
Since inductance is introduced between the output
terminals and the load, the transient performance of
the supply at the load is adversely affected.
- l0-4
This may
three units should be operated in parallel.