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Rugged Environment
AC-DC Converters >100 Watt
T Series
Edition 4/4.99
19/33
MELCHER
The Power Partners.
Connection in Series of Power Down and System
Good (Examples)
To achieve a logic OR function of the system good and
power down signal connect the D output to Sys In. The de-
sired function is then obtained from the system good out-
put. The output signal becomes high if the output voltage is
lower than the threshold of the power down circuit, inhibit is
applied or an internal error has occurred.
Internal
signals
20/22
Vo–
24
Sys In
26
Sys Out
Vo+
28
Inhibit
30
D
32
D set
Vo+
R
T 1000
06061
Fig. 35
System Good and Power Down connected in series.
Note: Output signal will indicate error at start-up.
Vo+
Sys Out
Vo–
T 1000
Sys In
Vo–
Vo+
Sys Out
Vo–
T 1000
Vo–
Overall
System
Good
Output
Control
Circuit
1 k
20 V
Output
Control
Circuit
1 k
20 V
Output
Control
Circuit
1 k
20 V
06059
CQ1
CQ2
CQn
22
24
12
26
24
26
12
Sys In
Fig. 36
Wired AND of electrically isolated open collector signals
(e.g. the OUT OK signal of CQ units) with the system
good signals of T units in series to achieve one signal
about the status of the whole system
Paralleling of Power Down and System Good
(Example)
To achieve a logic AND function of the System Good and
Power Down connect the D output with the system good
output. This combination generates an output signal only in
case of severe system errors. Only a T system fault to-
gether with a simultaneous Power Down of the output volt-
age will cause this output signal to become high imped-
ance.
Internal
signals
20/22
Vo–
24
Sys In
26
Sys Out
Vo+
28
Inhibit
30
D
32
D set
Vo+
R
T 1000
06062
Fig. 37
System Good and Power Down connected in parallel.