Cassette Style
100 Watt DC-DC Converters
S Series
Edition 1/01.2000
26/31
Fig. 28
Paralleling of single output units using option T with the
sense lines connected at the load
1 Leads should have equal length and cross sections and should
run in the same cable loom.
2 Diodes recommended in redundant operation only
3 DC common point
Load
1
2
3
S+
Vo+
Vo–
S–
Vi+
Vi–
T
Vi+
Vi–
S+
Vo+
Vo–
S–
T
1
max. 5 units in parallel connection
11036
Load
max. 5 units in parallel connection
+
–
Power bus
Module
Vo2–
Vo2+
Vo1–
Vo1+
T
Module
Vo2–
Vo2+
Vo1–
Vo1+
T
11037
Fig. 29
Paralleling of double output units using option T (e.g.
Powerbus)
Vo+
Vo–
Vo+
Vo–
Load
Vo+
Vo–
11003
Fig. 27
An example of poor wiring for connection in parallel
T Current Sharing
This option ensures that the output currents are approxi-
mately shared between all paralleled modules, hence in-
creasing system reliability. To use this facility, simply inter-
connect the T pins of all modules and make sure, that pins
14, the S– pins (S 1000) or the Vo1– pins (S 2000) are also
connected together. The load leads should have equal
length and cross section to ensure equal voltage drops. Not
more than 5 units should be connected in parallel.
Note: If output voltage adjustment is requested we strongly
recommend to use the R-input instead of option P, as with
option P the required setting accuracy is difficult to achieve.
The output voltages must be individually set prior to paral-
leling to within a tolerance of 1...2% or the R pins should be
connected together.
P Potentiometer
The potentiometer provides an output voltage adjustment
range of +10/–60% of
Uo nom and is accessible through a
hole in the front cover. This feature enables compensation
of voltage drops across the connector and wiring. Option P
is not recommended if units are connected in parallel.
Option P excludes the R-function. With double output units
both outputs are affected by the potentiometer setting (dou-
bling the voltage setting if the outputs are in series).
If the output voltages are increased above
Uo nom via R-in-
put control, option P setting, remote sensing or option T, the
output current(s) should be reduced accordingly so that
Po nom is not exceeded.
D Undervoltage Monitor
The input and/or output undervoltage monitoring circuit op-
erates independently of the built-in input undervoltage lock-
out circuit. A logic "low" (JFET output) or "high" signal (NPN
output) is generated at pin 20 as soon as one of the moni-
tored voltages drops below the preselected threshold level
Ut. The return for this signal is Vo1–. The D output recovers
when the monitored voltage(s) exceed(s)
Ut + Uh. The
threshold levels
Uti and Uto are either adjustable by a poten-
tiometer, accessible through a hole in the front cover, or fac-
tory adjusted to a fixed value specified by the customer.
Option D exists in various versions D0...DD as shown in the
following table.