Crane Aerospace & Electronics Power Solutions
SMRT Single, Dual and Triple DC/DC Converters
28 VOLT INPUT – 35 WATT
I
NHIBIT
F
UNCTION
The SMRT Series incorporates an inhibit terminal that can be
used to disable internal switching. The converter is inhibited
when a low (≤ 0.4 V) signal is applied to the inhibit pin. In the
inhibit mode the inhibit pin current requirement is less than ~2
mA. The converter resumes normal operation when a high (≥ 2.4
V) signal or open circuit is applied to the inhibit pin. The open
circuit voltage of the inhibit is 5 to 6 volts.The maximum allowable
voltage applied to the inhibit pin is 10 VDC.
S
CREENING
SMRT converters offer the following screening options: Space
Prototype (O), Class H, or Class K. Radiation tolerant to
Radiation Hardness Assurance (RHA) levels of “-” (O), “P”, “R” or
“F”, per MIL-PRF-38534. Interpoint model numbers use an “O” in
the RHA designator position to indicate the “-” (dash) Radiation
Hardness Assurance level of MIL-PRF-38534, which is defined
as “no RHA”. See “Class H and K, MIL-PRF-38534 Screening”
tables for more information.
EMI
S
YNCHRONIZATION
An isolated sync input allows this input to be connected to any of
the devices three returns. It can be referenced to the input return
or any of the output returns. Input current into this pin is limited
by a series 1k ohm resistance.
The SMRT has a built-in EMI input filter which brings the
conducted emissions into compliance with both methods of
MIL-STD-461, revisions C-CE03 and D-/E-CE102.
S
ENSE
Tight load regulation is maintained via wide bandwidth magnetic
feedback and through the use of remote sense on single output
models and one output (Output “A”) of the dual units. The sense
feature can be used to adjust the output voltage by connecting a
resistor between the sense line and the positive output.
O
UTPUT
V
OLTAGE
T
RIM
The output voltage of each set can be trimmed up by up to 25%,
or down by up to 45% of nominal (varies by model, see trim
instructions). The following are “sets” of voltages in relation to
trim:
• Triple output models: Main output is one set, the dual outputs are
another set.
• Dual outputs: Each output is a “set.”
One set can be trimmed using the trim pin, the other set can be
trimmed (up only) using the sense pin.
• Single: One set
S
ENSE
A
DJUST
I
NSTRUCTIONS
(U
P
O
NLY
)
- D
UAL
U
NITS
O
UTPUT
A O
NLY
(See trim tables on page 4)
5V Dual Sense Adjust:
Max. 5.40 V
R
EXTERNAL
= 30 (
Vdesired - 5
)
0.675 - 0.125 Vdesired
R
ADIATION
H
ARDENED
The SMRT DC/DC converters are designed to provide continuous
normal operation through radiation levels associated with space
missions and in tactical and strategic military environments. The
converters will operate normally in radiation environments with up
to 1 x 10
12
neutrons per square centimeter neutron fluence,
10
11
rads(Si) per second dose rate, and 3x10
5
rads(Si) total
dose. These levels of radiation tolerance make the SMRT
converters suitable for electronics in programs where operation in
high radiation environments is required.
At the highest dose rate (10
11
rads(Si)/sec dose rate) there
will be an upset resulting in a dip in the voltage. This is non-
destructive to the unit. The converter will operate through the
upset.
12V Dual Sense Adjust:
Max. 12.48 V
R
EXTERNAL
= 600 (
5 x Vdesired - 60.42
)
156 - 12.5Vdesired
15V Dual Sense Adjust:
Max 15.36 V
R
EXTERNAL
= 600 (
Vdesired - 15
)
38.4 - 2.5Vdesired
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Rev B – 20080213
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