Crane Aerospace & Electronics Power Solutions
sMFL single and dual dc/dc converters
28 VoLt input – 65 Watt
Features
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Fully qualified to Class H or K
–55° to +125°C operation
16 to 40 VDC input
Fully Isolated
Magnetic feedback
Fixed frequency, 600 kHz typical
Topology – Single Ended Forward
Inhibit input side and output side
Sync function
50 V for up to 120 ms transient protection
VDc O
utPut
SINgLE
3.3
5
12
15
DUAL
±5
±12
±15
MODELS
Output trim on single output models
Indefinite short circuit protection
Up to 85% efficiency / 43 W/in
3
Parallelable up to 148 watts
Remote sense on single output models
description
The SMFL Series™ 28-volt DC/DC converters are rated up to 65 watts
output power over a -55° to +125°C temperature range with a 28 Vdc
nominal input. On dual output models up to 70% of the rated output
power can be drawn from either the positive or negative outputs. Current
sharing allows the units to be paralleled for total power of up to 148
watts. The welded, hermetically sealed package is only 3.0 x 1.5 x 0.40
inches, giving the series an overall power density of up to 45 watts per
cubic inch.
i
nhibit
S
creening
SMFL converters offer the following screening options: Space Prototype
(O), Class H, or Class K. Radiation tolerant to Radiation Hardness
Assurance (RHA) levels of “-” (O) or “R”, per MIL-STD-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, QML Screening” tables for
more information.
The SMFL Series converters have two TTL compatible inhibit terminals
(INH1 and INH2) that can be used to disable power conversion, resulting
in a very low quiescent input current and no generation of switching
noise. An open collector TTL compatible low (<0.8 volts) is required to
inhibit the converter between INH1 (pin 4) and Input Common (pin 2). An
open collector TTL compatible low (<0.5 volts) is required to inhibit the
converter between INH2 (pin 12) and Output Common (pin 8). The appli-
cation of intermediate voltages to these pins (1.5 to 10.5 volts) should be
avoided.
S
ync
Converters may be synced to an external clock (525 to 675 kHz) or
to one another by using the sync in or out pins. The nominal free-run
switching frequency is 600 kHz.
D
eSign
F
eatureS
c
urrent anD
P
arallel
O
PeratiOn
SMFL Series converters are switching regulators that use a quasi-square
wave, single ended forward converter design with a constant switching
frequency of 600 kHz typical.
Isolation between input and output circuits is provided with a transformer
in the forward path and a wide bandwidth magnetic coupling in the feed-
back control loop. The SMFL uses a unique dual loop feedback technique
that controls output current with an inner feedback loop and an output
voltage with a cascaded voltage mode feedback loop. The additional
secondary current mode feedback loop improves transient response in
a manner similar to primary current mode control and allows for ease of
paralleling, but without the cost and complexity.
The constant frequency, pulse-width modulated converters use a quasi-
square wave single-ended forward design. Tight load regulation is
achieved through a wide-bandwidth magnetic feedback circuit. The output
voltage on single SMFL models can be trimmed to a specific output
voltage by adding an external resistor.
Multiple single output SMFL converters may be used in parallel to drive a
common load. In this mode of operation the load current is shared by two
or three SMFL converters. In current sharing mode, one SMFL converter
is designated as a master. The SLAVE pin (pin 11) of the master is left
unconnected and the MSTR/INH2 pin (pin 12) of the master is connected
to the SLAVE pin (pin 11) of the slave units. The units designated as
slaves have the MSTR/INH2 pin (pin 12) connected to the SNS RTN
pin (pin 9). Note that synchronizing the units together is not required for
current sharing operation. A second slave unit may be placed in parallel
with a master and slave; this requires the TRI pin (pin 3) of the master
unit to be connected to the SNS RTN pin (pin 9). See Figure 2 for a block
diagram of parallel connections.
When paralleled, 76% of the total combined power ratings of the SMFL
converters are available at the load. Overload and short circuit perfor-
mance are not adversely affected during parallel operation.
Crane Aerospace & Electronics
Electronics group (Interpoint Brand)
PO Box 97005 • Redmond WA 98073-9705
425.882.3100 • electronics@craneae.com
www.craneae.com
Page 1 of 13
Rev H - 20061102
Crane Aerospace & Electronics Power Solutions
sMFL single and dual dc/dc converters
28 VoLt input – 65 Watt
input Voltage range
• 16 to 40 VDC continuous
• 50 V for 120 ms transient
output power
• 40 to 65 watts depending on model
Lead soldering temperature (10 sec per lead)
• 300°C
storage temperature range (case)
• –65°C to +150°C
power dissipation (pd)
• 14 watts (16 watts SMFL2805S, SMFL2805D)
case operating temperature (tc)
• –55°C to +125°C full power
derate output power/current
• MFL283R3S: linearly from 100% at 100 °C to 80% at 125 °C
output Voltage temperature coefficient
• 100 ppm/°C typical
input to output capacitance
• 150 pF, typical
current Limit
• 125% of full load typical
isolation
• 100 megohm minimum at 500 V
audio rejection
• 50 dB typical
conversion Frequency (-55°c to 125°c)
• Free run mode 600 kHz typical
525 kHz. min, 675 kHz max
inhibit pin Voltage (unit enabled)
• INH1 = 9 to12 V, INH2 = 6 to 9 V
OPERATING CONDITIONS AND ChARACTERISTICS
SyNC IN AND INhIbIT (INh1, INh2)
sync in (525 to 675 kHz)
• Duty cycle 40% min, 60% max
• Logic low 0.8 V max
• Logic high 4.5 V min, 5 V max
• Referenced to input common
sync out
• Referenced to input common
inhibit (inH1, inH2) ttL open collector
• Logic low (output disabled)
INH1 referenced to input common
Logic low 0.8 V max
Inhibit pin current 10 mA max
INH2 referenced to output common
Logic low 0.5 V max
Inhibit pin current 5 mA max
• Logic high (output enabled)
Open collector
MEChANICAL AND ENvIRONMENTAL
size (maximum)
3.005 x 1.505 x 0.400 inches (76.33 x 38.23 x 10.16 mm)
See case U for dimensions.
Case options V, W, Y, and Z are available by special order.
Weight (maximum)
86 grams
screening
Space Prototype (O), Class H, or Class K
Radiation tolerant to Radiation Hardness Assurance (RHA) levels of “-” (O) or “R”, per MIL-STD-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, QML Screening” tables for more information.
Available configurations: OO, HO, HR, KR
www.craneae.com
Page 3 of 13
Rev H - 20061102
Crane Aerospace & Electronics Power Solutions
sMFL single and dual dc/dc converters
28 VoLt input – 65 Watt
MODEL NUMbERING kEy
Base Model
Input Voltage
SMFL
28 05 S / K
R
SMD NUMbERS
S
tanDarD
m
icrOcircuit
D
rawing
(SmD)
IN PROCESS
5962-9316302HxC
5962-9316202HxC
5962-9316102HxC
IN PROCESS
IN PROCESS
5962-9319302HxC
SmFl S
erieS
S
imilar
P
art
SMFL283R3S/HO
SMFL2805S/HO
SMFL2812S/HO
SMFL2815S/HO
SMFL2805D/HO
SMFL2812D/HO
SMFL2815D/HO
Number of Outputs
(S = single, D = dual)
Screening
RHA level
Output Voltage
The SMD number shown is for Class H screening, non-flanged,
and no Radiation Hardness Assurance (RHA) level. See the
SMD for the numbers for other screening and RHA levels.
For exact specifications for an SMD product, refer to the SMD
drawing. Call your Interpoint representative for status on the
SMFL SMD releases which are “in process.” SMDs can be down-
loaded from:
http://www.dscc.dla.mil/programs/smcr
ModeL seLection
SMFL28
Base model
V
out
value
number of outputs
case option
/
screening
Choose one from each of the following rows
V
out
value
Number of outputs
Case option
Screening
which is defined as “no RHA”
singles: 3R3, 5, 12, 15
duals: 5,12,15
“R” = decimal point, 3R3 = 3.3VDC
S (single)
or D (dual)
standard (case U, leave blank)
V, W, Y and Z available by special order
OO* - Space prototype, HO, HR, KR
*
Interpoint model numbers use an “O” in the RHA designator position to indicate the “-” (dash) Radiation Hardness Assurance level of MIL-PRF-38534,
www.craneae.com
Page 5 of 13
Rev H - 20061102
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