Crane Aerospace & Electronics Power Solutions
sMrt28 single, Dual and triple space Dc/Dc converters
28 VOLt Input – 35 Watt – space quaLIFIeD
u
nDerVOltage
l
OCkOut
The converters have an undervoltage lockout that will allow
power conversion at approximately 17 volts on a rising input
voltage and a conversion shut-down on a falling voltage at
approximately 14.5 volts.
At the highest dose rate (10
11
rad(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.
S
CreenIng
I
nhIbIt
F
unCtIOn
The SMRT28 Series incorporates an inhibit terminal that can be
used to disable internal switching. It is not recommended to tie
the Inhibit pin of an SMRT28 directly to the Inhibit pin of another
converter as the SMRT28 Inhibit pin can sink current. When
pulling multiple inhibit signals low a separate interface is recom-
mended for each SMRT28. The converter is inhibited when the
inhibit pin is pulled low (0.4 V). 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. Although open circuit is the preferred method for the
enabled state, up to 10 volts may be applied to the inhibit pin.
SMRT28 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 Screening Tables 1, 2 and 3 for more information.
emI
The SMRT28 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-/F-CE102.
S
enSe
S
ynChrOnIzatIOn
The Sync Input is isolated which allows Sync Return to be tied to
the primary side, secondary side, or float with respect to all inputs
and outputs. Input current into this pin is limited by a series 1 k
ohm resistance.
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 positive sense line and the positive output.
O
utput
V
Oltage
t
rIm
The output voltage of each set can be trimmed from 51% to
125% of nominal (varies by model, see trim instructions on page
4). 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 positive sense pin.
• Single: One set
The SMRT28 DC/DC converters are designed to provide contin-
uous normal operation through radiation levels associated with
space missions and in tactical and strategic military environ-
ments. The converters will operate normally in radiation environ-
ments with up to 1 x 10
12
neutrons per square centimeter neutron
fluence, 10
11
rad(Si) per second dose rate, and 3x10
5
rad(Si)
total dose.
These levels of radiation tolerance make the SMRT28 converters
suitable for electronics in programs where operation in high radia-
tion environments is required.
(see trim tables on page 4 for more options)
S
enSe
A
djuSt
I
nStructIonS for
o
utput
A
on
d
uAl
M
odelS
A
djuSt
u
p
o
nly
R
a
DjuSt
= 240
(
Vout - Vnom
Vmax - Vout
)
r
aDIatIOn
t
OleranCe
Vout = desired output voltage
Vnom = nominal unadjusted output voltage
Vmax = maximum achievable output voltage
5V Vmax = 6.0 V
12V Vmax = 14.68 V
15V Vmax = 18.36V
note: R
ADJUST
should be connected
between Sense A (pin 8) and Vout A (pin 11).
www.interpoint.com
Page 2 of 19
SMRT28 Rev E - 20100216
INTERPOINT [ INTERPOINT CORPORATION COMPANY ]
