Crane Aerospace & Electronics Power Solutions
sMrt28 single, Dual and triple space Dc/Dc converters
28 VOLt Input – 35 Watt – space quaLIFIeD
Features
Built in MIL-stD-461 eMI filter
• Operating temperature -55° to +125°C
Output trim from 51% to 124% of nominal
• Qualified to MIL-PRF-38534 Class H and K
• Radiation hardness assurance (RHA) to
level F 300 kRad(Si)
• Input voltage range 19 to 56 VDC
• Fully isolated, 5 port isolation
• Dual magnetic feedback
• Remote sense
• Transient protection 80 V for 100 ms
• Fixed high frequency switching
• Inhibit function
• Synchronization input
• Radiation tolerant to
• Indefinite short circuit protection
- 1 x 10
12
protons/cm
2
neutron or proton fluence
- 3 x 10
5
rad(Si) total dose
- 10
11
rad(Si)/sec dose rate
VDC O
utput
SIngLE
3.3
5
8.7
12
15
DUAL
±5
±12
±15
MODELS
• Meets MIL-STD-704A transient standards
- SEE - LET to 80 MeV cm
2
/mg
TRIPLE
+3.3 & ±12
+3.3 & ±15
+5 & ±7
+5 & ±12
+5 & ±15
DescrIptIOn
The SMRT28 Series™ of DC/DC converters offers up to 35
watts of power in a radiation tolerant design. The low profile
SMRT28 converters are manufactured in Interpoint’s fully certi-
fied and qualified MIL-PRF-38534 production facility and pack-
aged in hermetically sealed steel cases. They are ideal for use in
programs requiring high reliability, small size, and high levels of
radiation hardening assurance.
The SMRT28 converters are switching regulators which use a
two-phase, phase shifted flyback design with a nominal switching
frequency of 300 kHz. Close regulation is maintained with
advanced constant frequency pulse width modulation design
techniques. The SMRT28’s feed-forward compensation and
discontinuous topologies provide high levels (80 dB peak) of
input-to-output ripple rejection.
A minimum load of 2% of full load should be used on outputs at
TID of 100 kRad(Si) or greater to ensure tight regulation over the
full input range. The converter should not be inhibited or oper-
ated below 19 Vin above 5x10
4
rad(Si) total dose.
Two independent feedback loops are used to regulate the dual
and triple outputs, one feedback loop regulates the two-phased
single output. Each set of outputs is electrically isolated from the
other and from the input. This product configuration eliminates
cross regulation effects between output sets.
Configurations:
• Single Output: One two-phase single output
• Dual Output: Two single-phase single outputs
• Triple Output: One single-phase independent
Main output and one single-phase dual output.
(± Auxiliary output)
Crane Aerospace & Electronics
Electronics group (Interpoint Brand)
PO Box 97005 • Redmond WA 98073-9705
425.882.3100 • power@crane-eg.com
www.interpoint.com
The information in this document is a derivative of a document cleared
by the Department of Defense (DoD) Office of Security Review (OSR) for
public release. OSR case number 09-S-1960 dated June 22, 2009.
SMRT28 Rev E - 20100216
Page 1 of 19
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
Crane Aerospace & Electronics Power Solutions
sMrt28 single, Dual and triple space Dc/Dc converters
28 VOLt Input – 35 Watt – space quaLIFIeD
Operating COnditiOns and CharaCteristiCs
Input Voltage range
• 19 to 56 VDC continuous
• 80 V for 100 ms transient
conversion Frequency
• 300 kHz typ 270 kHz min, 330 kHz max
Output power
• Up to 35 watts depending on model
Lead soldering temperature (10 sec per pin)
• 300°C
storage temperature range (case)
• -65°C to +150°C
radiation (will operate through)
• 1x10
12
neutrons/cm
2
neutron or proton fluence
• Radiation dose rate 10
11
rad(Si) /sec
• Total dose up to 300 kRad(Si)
• SEE - LET to 80 MeV cm
2
/mg
synC and inhibit
sync
• Input frequency 270-330 kHz
• Duty cycle 20% min, 80% max
• 2.5 V p-p minimum amplitude
• 10 V p-p maximum amplitude
• Sync circuit is floating and isolated
• If sync is used at lower end of the range, full load
operation is not guaranteed.
Inhibit
• Active low (output disabled)
‣
InH referenced to input common
‣
Active low, pulled to 0.4 V or lower
‣
Inhibit pin current < 2mA
• Active high (output enabled)
‣
High >2.4V
‣
not to exceed 10V
‣
Open pin voltage 5 to 6 volts
case Operating temperature (tc)
• -55°C to +125°C full power
• -55°C to +135°C absolute
Derating Output power/current
• Linearly from 100% at 125°C to 0% at 135°C
power Dissipation (pd)
• 20 to 31 W
current Limit
• 125% of full load typical
Output Voltage temperature coefficient
• 100 ppm/°C max
Isolation at 25°c
• 100 megohm minimum at 500 V
audio rejection
• 50 dB typical
meChaniCal and envirOnmental
size (maximum)
• 2.705 x 2.205 x 0.400 inches (68.71 x 56.01 x 10.16 mm)
‣
See case S for dimensions.
Weight (maximum)
• 100 grams maximum
screening
Space Prototype, Class H, or Class K are 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. Available
configurations: OO, HP, HR, KP, KR, KF
www.interpoint.com
Page 3 of 19
SMRT28 Rev E - 20100216
Crane Aerospace & Electronics Power Solutions
sMrt28 single, Dual and triple space Dc/Dc converters
28 VOLt Input – 35 Watt – space quaLIFIeD
t
rIm DOwn
Singles
Duals
trIM taBLes
t
rIm
u
p
Singles
Duals
R
trIm
should be connected between the
trim
pin and
positive sense
pin. R
trIm
should be connected between the
trim
pin and
sense return
pin.
R
trIm
should be connected between the
trim B
pin and
positive Vout B
pin. This only trims output B, output A can use the sense pin to trim up
only. See page 2 for instructions on trimming up output A.
R
trIm
should be connected between the
trim B
pin and
Vout B return
pin.
This only trims output B, output A can use the sense pin to trim up only.
Triples
Triples
R
trIm
should be connected between the
trim a
pin and
positive Vout
a
pin to adjust the Main output.
R
trIm
should be connected between the
trim B
pin and
positive Vout
B
pin to adjust the Auxiliary outputs.
R
trIm
Vout - Vmin
=K(
)
Vnom - Vout
R
trIm
should be connected between the
trim a
pin and
Vout a return
pin
to adjust the Main outputs.
R
trIm
should be connected between the
trim B
pin and
Vout B return
pin
to adjust the Auxiliary outputs.
R
trIm
= K (
Vmax - Vout
)
Vout - Vnom
Vout = Desired Voltage; K/Vmin/Vnom from table below.
Vout = Desired Voltage; K/Vmax/Vnom from table below.
V
nOM
3.3
5.0
7.0
8.7
12
15
K
3500
4520
8020
9040
11030
12900
V
MIn
3.18
4.16
5.47
6.13
7.05
7.65
% OF V
nOM
96
83
78
70
58
51
V
nOM
3.3
5.0
7.0
8.7
12
15
K
3000
3000
5300
5300
5300
5300
V
MAX
3.70
6.26
8.27
10.46
14.69
18.54
% OF V
nOM
112
125
118
149
122
124
note: Do not exceed maximum current rating when trimming down,
note: Do not exceed maximum power rating when trimming up.
1
2
3
4
5
SMRT Single
14
Trim 12
10
Sense 8
9
11
13
1
2
3
4
5
SMRT Single
14
Trim 12
10
8
11
13
Sense Return 9
1
2
3
4
5
Vout B Return 14
Trim B 12
10
9
8
11
13
1
2
3
4
5
SMRT Dual
Vout B 13
Trim B 12
10
9
8
1
2
3
4
5
SMRT Triple
Vout A Return 13
Trim A 12
11
9
14
11
14
SMRT Dual
1
2
3
4
5
SMRT Triple
Vout A 13
+Vout B 11
9
Trim A 12
10
14
Vout B Return 10
Trim B 8
Trim B 8
F
Igure
1: t
rIm
D
Own
D
IagramS
www.interpoint.com
F
Igure
2: t
rIm
u
p
D
IagramS
Page 4 of 19
SMRT28 Rev E - 20100216
Crane Aerospace & Electronics Power Solutions
sMrt28 single, Dual and triple space Dc/Dc converters
28 VOLt Input – 35 Watt – space quaLIFIeD
pin
single Output
Dual Output
Vin
Vin Return
Inhibit
Sync In
pIn Out
1
2
3
4
5
8
9
Vin
Vin Return
Inhibit
Sync In
Sense
Vin
triple Output
Vin Return
Inhibit
Sync In
Trim B
Sync Return
Sense Return
Vout A
Trim
Vout A
Sync Return
Sense A
Sense A Return
Vout A Return
Vout A
Trim B
Vout B
Sync Return
Vout B negative
Vout B Return
Trim A
Vout B Positive
Vout A
10
11
12
13
14
Vout A Return
Vout A Return
Vout B Return
Vout A Return
1
2
3
4
5
TOP VIEW
See case S for dimensions.
14
13
12
11
10
9
8
F
Igure
3: p
In
O
ut
Inhibit: single, dual and triple
Sync In
Sense Lines
Trim (all)
pIns nOt In use
Leave unconnected
Connect to Sync Return
Leave unconnected
Must be connected to appropriate outputs
www.interpoint.com
Page 5 of 19
SMRT28 Rev E - 20100216
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
