
Cassette Style
DC-DC Converters
Q Series
Edition 5/5.2000
10/25
Parallel or Series Connection of Outputs and/or Units
Single or double output units with equal nominal output volt-
age can be connected in parallel without any precaution by
interconnecting the T-pins for approximate equal current
sharing. (See:
Auxiliary Functions.)
Any double output unit with its outputs in parallel behaves
like a single output unit, i.e. is fully regulated. There is no
inconvenience or restriction using the R-input and the
sense lines .
Single output units and/or main and second outputs of dou-
ble output units can be connected in series with any other
(similar) output. For double output modules consider, that
the effect via sense lines, R-input or option P is doubled.
load
Vo1+ (Vo2+)
Vo1–
Vo1– (Vo2–)
S–
S+
Vo1+
Single (double)
output
T
Vi–
Vi+
i
Out OK –
Out OK+
Vo1+ (Vo2+)
Vo1–
Vo1– (Vo2–)
S–
S+
Vo1+
Single (double)
output
T
Vi–
Vi+
i
Out OK –
Out OK+
+
i
+
–
Rp
05091
load
Vo1+
Vo2–
Vo1–
S–
S+
Vo2+
Double output
Vi–
Vi+
i
Out OK –
Out OK+
Vi–
Vi+
i
Out OK –
Out OK+
+
i
+
–
Vo1+
Vo2–
Vo1–
S–
S+
Vo2+
Double output
Rp
05092
Fig. 8
Parallel connection of outputs and/or several modules,
sense lines connected at connector side
Fig. 9
Series connection of outputs and/or several modules,
sense lines connected at connector side only
Note:
– Parallel connection of several double output units should
always include both, main and second output to maintain
good regulation of all outputs.
– 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.
– Rated output voltages above 48 V (SELV = Safety Extra
Low Voltage) need additional measures in order to com-
ply with international safety requirements.
Uod
td
Uo ±1%
t
≥10 s
Uo
0
0.5
1
Io/Io nom
05102
Dynamic Load Regulation
Fig. 10
Control deviation of Uo versus dynamic load change
Hold up Time
The modules provide virtually no hold up time. If hold up
time is required, use external output capacitors or decou-
pling diodes and input capacitors of adequate size.
Formula for additional external input capacitor
2
Po th 100
Ci ext = –––––––––––––––
h (Uti 2 – Ui min2)
where as:
Ci ext = external input capacitance [mF]
Po
= output power [W]
h
= efficiency [%]
th
= hold-up time [ms]
Ui min = minimum input voltage [V]
Uti
= threshold level [V]