Crane Aerospace & Electronics Power Solutions
Mor single and dual dc/dc converters
28 Volt input – 120 Watt
i
nhibit
1
and
2
u
nderVoltage
l
oCkout
Two inhibit terminals disable switching, resulting in no output
and very low quiescent input current. The two inhibit pins allow
access to an inhibit function on either side of the isolation barrier
to help maintain isolation.
An open collector is required for interfacing with both of the
inhibit pins. Applying an active low to either inhibit pin will inhibit
the converter. Leaving the pins open will enable the converter.
Inhibit 1 is referenced to Input Common. Inhibit 2 is refer-
enced to Sense Return for single output models and to Output
Common for dual output models.
The open circuit voltage (unit enabled) for Inhibit 1 is 13 V
and for Inhibit 2 it is up to 8 V. Leave the Inhibit pins uncon-
nected if not used. The required active low voltage level is 0.8
V maximum for Inhibit 1 and 0.2 V maximum for Inhibit 2. See
Figures 4 and 5.
Undervoltage lockout prevents the units from operating below
approximately 15.5 VDC input voltage to keep system current
levels smooth, especially during initialization or re-start opera-
tions.
S
ynC
i
n and
S
ynC
o
ut
The MOR converters can be synchronized to the system clock
by applying an active high sync signal to the Sync In pin. Sync
Out can be used to synchronize other components to the MOR
converter’s switching frequency.
V
CC
~
5V
~
10 k
10 k
Sync In
Input
Common
330 pF
1.8 k
1k
Positive
Input
20 k
Inhibit 1
Input
Common
10 k
12V
F
igure
6: S
ynC
i
n
200
V
CC
The frequency range for external synchronization is 525 to 625
kHz. The requirements for an external signal are 15% to 50%
duty cycle, 0 ≤ L ≤ 0.8 V and 4.5 ≤ H ≤ 9 V. Both Sync In and
Sync Out are referenced to input common. Sync In should be
connected to input common if not used. See Figures 6 and 7.
V
CC
~
200
Ω
MOR Input Side
F
igure
4: i
nhibit
1
Sync Out
Input
Common
Current
Limit
V
S
~
10 k
F
igure
7: S
ynC
o
ut
Voltage
E/A
P
oSitiVe
o
utPut
, n
egatiVe
o
utPut and
o
utPut
C
ommon
200
Feedback
Inhibit 2
Sense
Return
Output current is typically limited to 125% of maximum specified
current under short circuit or load fault conditions.
Single output models operate from no load to full load. Dual
output models with balanced loads operate from no load to full
load. For dual models with unbalanced loads, at least 10% of
the total output power must be drawn from the positive output
at all times, however, the negative output does not require a
minimum load. See note 4, cross regulation, under the Electrical
Characteristics Tables.
Page 3 of 24
MOR Rev K - 20100422
MOR Output Side - Single Output
F
igure
5: i
nhibit
2
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