Cassette Style
100 Watt AC-DC Converters
S Series PFC
Edition 01/01.2001
9/27
Output Voltage Regulation of Double Output Modules
Output 1 is under normal conditions regulated to U
o1 nom
,
independent of the output currents.
U
o2
is dependent upon the load distribution. If both outputs
are loaded with more than 10% of I
o nom
, the deviation of
U
o2
remains within
±
5% of the value of U
o1
. The following 3
fi
gures show the regulation with varying load distribution. If
I
o1
= I
o2
or the two outputs are connected in series, the de-
viation of U
o2
remains within
±
1% of the value of U
o1
pro-
vided that a total load of more than 10% of I
o nom
is applied.
Two outputs of a single S 5000 module connected in paral-
lel will behave like the output of a S 4000 module; the paral-
leled output is fully regulated. No precautions are neces-
sary in using the R-input and the test sockets.
U
o
U
o nom
0.98
0.5
0
0.5
1.0
I
o1
I
oL
I
o
I
o nom
05001
Fig. 9
U
o1
vs. I
o1
(typ.) of single output units
Thermal Considerations
If a converter is located in free, quasi-stationary air (con-
vection cooling) at the indicated maximum ambient tem-
perature T
A max
(see table: Temperature specifications) and
is operated at its nominal input voltage and output power,
the temperature measured at the Measuring point of case
temperature T
C
(see: Mechanical Data) will approach the
indicated value T
C max
after the warm-up phase. However,
the relationship between T
A
and T
C
depends heavily on the
conditions of operation and integration into a system. The
thermal conditions are influenced by input voltage, output
current, airflow and temperature of surrounding compo-
nents and surfaces. T
A max
is therefore, contrary to T
C max
,
an indicative value only.
Caution:
The installer must ensure that under all operat-
ing conditions T
C
remains within the limits stated in the
table: Temperature specifications.
Notes:
Sufficient forced cooling or an additional heat sink
allows T
A
to be higher than 71
°
C (e.g. 85
°
C) if T
C max
is not
exceeded.
For -7 or -9 units at an ambient temperature T
A
of 85
°
C with
only convection cooling, the maximum permissible current
for each output is approx. 40% of its nominal value as per
figure.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
50
60
70
80
90
100
I
o
/
I
o nom
T
A
[
°
C]
0.9
1.0
Forced cooling
0
T
A min
T
C max
Convection cooling
Fig. 8
Output current derating versus temperature for -7 and -9
units.
Thermal Protection
A temperature sensor generates an internal inhibit signal
which disables the outputs if the case temperature exceeds
T
C max
. The outputs are automatically re-enabled if the tem-
perature drops below this limit.
It is recommended that continuous operation under simul-
taneous extreme worst case conditions of the following
three parameters be avoided: Minimum input voltage,
maximum output power and maximum temperature.
Output Protection
Each output is protected against overvoltage which could
occur due to a failure of the control circuit by means of a
voltage suppressor diode which, under worst case condi-
tions, may become a short circuit. The suppressor diodes
are not designed to withstand externally applied over-
voltages. Overload at any of the two outputs will cause a
shut-down of both outputs. A red LED indicates the over-
load condition.
Parallel or Series Connection of Units
Single or double output units with equal nominal output volt-
age can be connected in parallel without any precautions
using option T.
With option T (current sharing), all units share the current
approximately equally.
Single output units and/or main and second outputs of dou-
ble output units can be connected in series with any other
(similar) output.
Note:
–
Parallel connection of double output units should always
include both, main and second output to maintain good
regulation of both outputs.
–
Not more than 5 units should be connected in parallel.
–
Series connection of second outputs without involving
their main outputs should be avoided as regulation may
be poor.
–
The maximum output current is limited by the output with
the lowest current limitation if several outputs are con-
nected in series.
Output Voltage Regulation of Single or Double Output
Modules with Outputs 1 and 2 Connected in Series