Crane Aerospace & Electronics Power Solutions
sMFL single and dual dc/dc converters
28 VoLt input – 65 Watt
Features
• Operating temperature -55° to +125°C
parallel operation with current share, up to 3 units
(148 watts)
• Qualified to MIL-PRF-38534 Class H and K
• Input voltage range 16 to 40 VDC
• Fully isolated, magnetic feedback
• Fixed high frequency switching
• Inhibit function
• Radiation hardness assurance (RHA) to level R 100 kRad(Si)
• Transient protection 50 V for 120 ms
VDc O
utPut
SINgLe
3.3
5
12
15
DuAL
±5
±12
±15
MODeLS
• Remote sense and output trim on single output models
• Synchronization input and output
• Indefinite short circuit protection
• High power density, 85% efficiency
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 paral-
leled 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 43 watts per cubic inch.
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 feed-
back circuit. The output voltage on single SMFL models can
be trimmed to a specific output voltage by adding an external
resistor (see Figure 1 for resistor values).
S
creening
SMFL converters, also available on SMD drawings, offer the
following screening options: Space Prototype (O), Class H, or
Class K. Radiation tolerant to Radiation Hardness Assurance
(RHA) levels of “-” (O), “P,” or “R,” 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 - 3 for more information.
i
nhibit
D
eSign
F
eatureS
The SMFL Series converters have two 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 active low (<0.8 volts) is required to inhibit
the converter between INH1 (pin 4) and Input Common (pin
2). An active 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.
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 feedback 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
Crane Aerospace & electronics
electronics group (Interpoint Brand)
PO Box 97005 • Redmond WA 98073-9705
425.882.3100 • power@crane-eg.com
www.craneae.com/interpoint
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 (see Application Note
titled “Inhibit and Synchronization”).
c
urrent anD
P
arallel
O
PeratiOn
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
The information in this document is a derivative of documents cleared
by the Department of Defense (DoD) Office of Security Review (OSR) for public release.
OSR case numbers 09-S-0996 dated March 13, 2009 and 09-S-1960 dated June 22, 2009.
Page 1 of 15
SMFL Rev K - 20101209
Crane Aerospace & Electronics Power Solutions
sMFL single and dual dc/dc converters
28 VoLt input – 65 Watt
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 performance are not adversely affected during parallel
operation.
audio rejection
• 50 dB typical
Operating COnditiOns and CharaCteristiCs
input Voltage range
• 16 to 40 VDC continuous
• 50 V for 120 ms transient
output power
• 40 to 65 watts depending on model
conversion Frequency (-55°c to 125°c)
• Free run mode 600 kHz typical
‣
525 kHz. min, 675 kHz max
Lead soldering temperature (10 sec per lead)
• 300°C
storage temperature range (case)
• -65°C to +150°C
synC and inhibit (inh1, inh2)
sync
• Sync In
‣
Input frequency 525 to 675 Hz.
‣
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
power dissipation (pd)
• 14 watts (16 watts SMFL2805S, SMFL2805D)
case operating temperature (tc)
• -55°C to +125°C full power
input to output capacitance
• 150 pF, typical
current Limit
• 125% of full load typical
output Voltage temperature coefficient
• 100 ppm/°C typical
derating output power/current
• Linearly from 100% at 125°C to 0% at 135°C
• MFL283R3S: linearly from 100% at 100°C
to 85% at 125°C to 0% at 135°C
isolation
• 100 megohm minimum at 500 V
inhibit (inH1, inH2)
• Active low (output disabled)
‣
INH1 referenced to input common
- Active low 0.8 V max
- Inhibit pin current 10 mA max
‣
INH2 referenced to output common
- Active low 0.5 V max
- Inhibit pin current 5 mA max
• Active high (output enabled)
‣
Open collector (output enabled)
‣
Avoid intermediate voltages of 1.5 to 10.5
‣
Open pin voltage
- INH1 = 9 to 12 V
- INH2 = 9 V max
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 option V is also available.
Weight (maximum)
• 86 grams
screening
Space Prototype (O), Class H, or Class K are 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 designator position to indicate the “-” (dash)
Radiation Hardness Assurance level of MIL-PRF-38534, which is
defined as “no RHA”.
See Screening Tables 1 - 3 for more information. Available
configurations: OO, HP, KP, HR, KR
www.craneae.com/interpoint
Page 2 of 15
SMFL Rev K - 20101209
Crane Aerospace & Electronics Power Solutions
sMFL single and dual dc/dc converters
28 VoLt input – 65 Watt
sinGLe output ModeLs connection diaGraMs - triM, sense and paraLLeL
1
2
3
4
5
6
MSTR/INH2 12
Slave 11
Pos. Sense 10
9
Sense Return
8
Output Common
7
Positive Output
–
+
RL
28V
+
–
Positive Input
Input Common
TR1
INH1
Sync Out
Sync In
Inhibit
Sync In
REMOTE SENSE CONNECTION
1
2
3
4
5
6
Positive Input
Input Common
TR1
INH1
Sync Out
Sync In
MSTR/INH2 12
11
Slave
10
Pos. Sense
9
Sense Return
8
Output Common
7
Positive Output
28V
+
–
RA
–
+
RL
Inhibit
Sync In
OUTPUT VOLTAGE ADJUST CONNECTION
VOUT INCREASE
(VOLT)
0.1
0.2
0.3
0.4
0.5
RA (OHMS)
5–V
12–V
70
25
140
210
280
350
50
75
100
125
3.3-V
120
240
360
480
600
15–V
20
40
60
80
100
F
igure
1: S
enSe
c
OnnectiOnS anD
t
rim
t
able
– S
ingle
O
utPut
m
ODelS
28V
+
–
1
2
3
4
5
6
Positive Input
Input Common
TR1
INH1
Sync Out
Sync In
MSTR/INH2 12
Slave 11
Pos. Sense
Sense Return
Positive Output
10
9
8
7
–
+
RL
Inhibit
Sync In
MASTER
Output Common
CONNECT ONLY WHEN 2 SLAVES ARE USED
1
2
3
4
5
6
Positive Input
Input Common
TR1
INH1
Sync Out
Sync In
MSTR/INH2 12
Slave 11
Pos. Sense 10
Sense Return 9
Output Common 8
Positive Output
7
SLAVE 1
1
2
3
4
5
6
Positive Input
Input Common
TR1
INH1
Sync Out
Sync In
MSTR/INH2 12
Slave 11
Pos. Sense 10
Sense Return 9
SLAVE 2
Output Common 8
7
Positive Output
F
igure
2: P
arallel
c
OnnectiOnS
– S
ingle
O
utPut
m
ODelS
www.craneae.com/interpoint
Page 3 of 15
SMFL Rev K - 20101209
Crane Aerospace & Electronics Power Solutions
sMFL single and dual dc/dc converters
28 VoLt input – 65 Watt
pin out
1
2
3
4
5
6
7
8
9
10
11
12
pin
Positive Input
Triple (TR1)
Sync Out
Sync In
single output
Positive Input
Triple (TR1)
Sync Out
Sync In
dual output
pin
3
4
TR1
pins not in use
description
Inhibit 1 (INH1)
Sync Out
Sync In
Sense Return
Positive Sense
Slave
Master/Inhibit 2
action
Leave unconnected
Input Common
Inhibit 1 (INH1)
Input Common
Inhibit 1 (INH1)
5
6
9
10
11
12
Leave unconnected
Connect to Input
Common
Leave unconnected
Positive Output
Sense Return
Slave
Output Common
Positive Sense
Master/Inhibit 2
Positive Output
Connect to appropriate
outputs
Output Common
Negative Output
No connection
Slave
Connect to appropriate
outputs
Leave unconnected
Leave unconnected
Master/Inhibit 2
Angled corner indicates pin one.
1
2
3
4
5
6
12
TOP VIEW
SMFL
(Pin side, marked side)
See cases u and V for dimensions.
Case V has the same pin out.
11
10
9
8
7
F
igure
3: P
in
O
ut
www.craneae.com/interpoint
Page 4 of 15
SMFL Rev K - 20101209
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
V / K
R
sMd nuMbers
S
tandard
M
icrocircuit
d
rawing
(SMd)
5962R0621302KxC
5962R9316302KxC
5962R9316202KxC
5962R9316102KxC
5962R9319102KxC
5962R9319302KxC
5962R9319202KxC
SMFL S
erieS
S
iMiLar
P
art
SMFL283R3S/KR
SMFL2805S/KR
SMFL2812S/KR
SMFL2815S/KR
SMFL2805D/KR
SMFL2812D/KR
SMFL2815D/KR
Number of Outputs
(S = single, D = dual)
Case Option
(leave blank for standard case U)
Screening
Radiation Hardness
Assurance (RHA)
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. SMDs can be down-loaded from:
http://www.dscc.dla.mil/programs/smcr
o
n
the LineS beLow
,
enter one SeLection FroM each category to deterMine the ModeL nuMber
.
ModeL seLection
cateGory
sMFL28
Base Model and
Input Voltage
Output Voltage
1
3r3, 05, 12, 15
Number of Outputs
2
s
d
___________
Case/Lead
Options
3
(u, leave blank)
V
/
_______
Screening
4
o
H
k
RHA
5
o
p
r
seLection
SMFL28 is the only
available option
05, 12, 15
Notes:
1. Output Voltage: An R indicates a decimal point. 3R3 is 3.3 volts out.
2. Number of Outputs: S is a single output and D is a dual output
3. Case Options: For the standard case (case u) leave the case option blank. For case option V, insert the letter V in the case option position.
4. Screening: A screening level of O is a Space Prototype and is only used with RHA O. See Screening Tables 1, 2 and 3 for more information.
5. RHA: 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.” RHA O is only available with Screening level O. See Screening Table 3 for more information.
www.craneae.com/interpoint
Page 5 of 15
SMFL Rev K - 20101209
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