Crane Aerospace & Electronics Power Solutions
SMTR Single, Dual and Triple DC/DC Converters
28 VOlT INPuT – 30 WaTT – PENDINg REVISION F RElEaSE
FEaTuRES
Single, Dual and Triple models
• Operating temperature -55° to +125°C
• Radiation hardness assurance (RHA)
to level R 100 kRad(Si)
• Input voltage range 16 to 40 VDC
• Fully Isolated, magnetic feedback
• Transient protection 50 V for 50 ms
• Qualified to MIL-PRF-38534 Class H and K
• Fixed high frequency switching, 600 kHz
• Inhibit function
• Trim function or remote sense on single output models
• Synchronization function
• Indefinite short circuit protection
• Up to 84% efficiency (up to 73% efficiency triple models)
SIngLE
1.5
2.5
3.3
5
12
15
VDC O
utput
DUAL
TRIPLE
±5
+5 & ±12
±12
+5 & ±15
±15
MODELS
DESCRIPTION
The SMTR Series™ of 28 volt DC/DC converters offers up to
30 watts of output power from single, dual or triple output config-
urations. They operate over the full military temperature range of
-55°C to +125°C with up to 84% efficiency (up to 73% efficiency
triple models). SMTR converters are packaged in hermetically
sealed metal enclosures, making them ideal for use in military,
aerospace and other high reliability applications.
S
creening
SMTR converters offer screening options to Space Prototype (O),
Class H, or Class K. Radiation tolerant to Radiation Hardness
Assurance (RHA) levels of “-” (O), “P,” or “R,” per MIL-STD-
38534. Interpoint model numbers use an “O” in the RHA desig-
nator 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.
SMTR converters have internal input filter that help reduce the
need for external components in normal operation. For systems
that require compliance with MIL-STD-461C’s CE03 standard,
Interpoint offers filter/transient suppression modules (including
the SFMC-461 and SFCS28-461), which will result in compliance.
For the lowest noise performance, connection of the case to input
common is recommended. The connection can be hard-wired
or AC coupled with a small ceramic bypass capacitor. Indefinite
short circuit protection and overload protection are provided by
a constant current-limit feature. This protective system senses
current in the converter’s secondary stage and limits it to approxi-
mately 125% of the maximum rated output current.
S
ynchronization
c
onverter
D
eSign
The SMTR converters are constant frequency, pulse-width
modulated switching regulators which use a quasi-square wave,
single ended, forward converter design. Tight load regulation is
maintained by using a wide bandwidth magnetic feedback and,
on single output models, through use of remote sense. On dual
output models, the positive output is independently regulated and
the negative output is cross regulated through the use of tightly-
coupled magnetics. The SMTR Triple Series DC/DC converter’s
design includes individual regulators on the auxiliary outputs
which provide for no cross regulation error when a minimum
300 mA load is maintained on the main (+5) 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
Synchronizing the converter with the system clock allows the
designer to confine switching noise to clock transitions, mini-
mizing interference and reducing the need for filtering. In sync
mode, the converter will run at any frequency between 500 kHz
and 675 kHz. The sync control operates with an active high at
any duty cycle between 40% and 60%. The sync pin should be
connected to input common pin when not in use.
Rev F - 20090324 - Pending Revision F Release
Cleared by U.S. DoD OSR for Public Release
OSR case number 09S-0995, dated March 13, 2009.
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