DC/DC C
ONVERTERS
PIN DESCRIPTIONS AND FUNCTIONS
P
IN
O
UT
Pin
1
2
3
4
5
6
7
8
9
10
11
12
Single Output
Positive Input
Input Common
Trim
Inhibit 1(INH1)
Sync Out
Sync In
Positive Output
Output Common
Sense Return
Positive Sense
Share
Inhibit 2 (INH2)
Dual Output
Positive Input
Input Common
Case
Inhibit 1(INH1)
Sync Out
Sync In
Positive Output
Output Common
Negative Output
Trim
Share
Inhibit 2 (INH2)
MOR SERIES
120 WATT
3
Trim
T
RIM
Both single and dual output
models include a trim function.
Output voltage can be trimmed
from 60% up to 110% of nominal
V out . When trimming up, do not
exceed the maximum output
power. When trimming down, do
not exceed the maximum output
current.
Trim Formulas
Trim Up:
α
=
V
o
V
o nominal
V
o
2.5 – 1 • 20 – 50
(α -1)
Example: V
o nominal
= 5.0
,
V
o
= 5.25
,
α
= 1.05
,
R
T
= 390 kΩ
V
o
,
0.6
≤ α ≤
1.0
Trim Down:
α
=
V
o nominal
MOR
Single
Output
R
T
Positive Output 7
Positive Sense 10
TRIM UP
Sense Return
Output Common
9
8
TRIM
DOWN
F
IGURE
3: T
RIM
– S
INGLE
10 Trim
Positive Output
R
T
7
TRIM UP
MOR
Dual
Output
Output Common
8
TRIM DOWN
,
1.0
≤ α ≤
1.1
Negative Output
9
(
R
T
(kΩ) =
)
F
IGURE
4: T
RIM
– D
UAL
On dual models the positive
output is regulated and the
negative output is transformer
coupled (cross-regulated) to the
positive output. When trimming
the duals, both output voltages
will be adjusted equally.
R
T
(kΩ) = 50 •
α
– 30
1–
α
AND
I
NPUT
C
OMMON
Steady state voltage range is 16 to 40 VDC. Transient range is 40
to 50 V for a maximum of 120 msec. Low voltage 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 operations. All models include a soft-start
function to prevent large current draw and minimize overshoot.
P
OSITIVE
I
NPUT
Example: V
o nominal
= 5.0
,
V
o
= 4.5
,
α
= 0.9
,
R
T
= 150 kΩ
I
NHIBIT
1
AND
E
XTERNAL
I
NPUT
F
ILTERS
Internal 500 V capacitors are connected between the case and
input common and between the case and output common. See
Figure 1.
Interpoint’s FME filters are recommended to meet CE03 require-
ments for reflected input line current. When using an external
input filter it is important that the case of the filter and the case of
the converter be connected through as low as an impedance as
possible. Direct connection of the baseplates to chassis ground is
the best connection. If connected by a single trace, the trace
should be as wide as it is long.
C
ASE
AND
2
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
Positive
Input
required for inter-
200
Ω
facing with both of
the inhibit pins.
20 k
Applying an open-
10 k
collector TTL logic
12 V
V
CC
low to either inhibit
Inhibit 1
pin will inhibit the
Input
converter. Applying
Common
MOR Input Side
an open collector
F
IGURE
5: I
NHIBIT
– I
NPUT
S
IDE
TTL logic high or
leaving the pins
open will enable the converter. Inhibit 1 is referenced to Input
Common, while Inhibit 2 is referenced to Sense Return on the
output side.
Current
Limit
V
S
~
10 k
Voltage
E/A
1, 2, 3
Positive Input
Positive Output 10, 11, 12
1 Positive Input
28V
FME28-461
EMI Filter
4, 5, 6
Input Common
Output Common
7, 8, 9
Case*
MOR
Single or Dual
Output
2 Input Common
200
Ω
Feedback
Inhibit 2
Sense
Return
MOR Output Side
Chassis Ground
F
IGURE
2: E
XTERNAL
F
ILTER
C
ONNECTION
The
open
circuit
voltage for Inhibit 1 is
13 V and for Inhibit 2 it
is 8 V. Float the inhibit
pin(s) if not used. The
required logic low
voltage level is 0.2 V
maximum.
F
IGURE
6: I
NHIBIT
– O
UTPUT
S
IDE
5
INTERPOINT [ INTERPOINT CORPORATION COMPANY ]
