Crane Aerospace & Electronics Power Solutions
SMFL Single and Dual DC/DC Converters
28 Volt input – 65 Watt
Features
parallel operation with current share, up to 3 units (up
to 185 watts)
• Operating temperature -55° to +125°C
• Qualified to MIL-PRF-38534 Class H and K
• Radiation hardness assurance (RHA) to level R 100 kRad(Si)
• Input voltage range 16 to 40 VDC
• Transient protection 80 V for 50 ms
• Fully isolated, magnetic feedback
• Fixed high frequency switching
• Remote sense and output trim on single output models
• Inhibit function
• Synchronization input and output
• Indefinite short circuit protection
• High power density with up to 85% efficiency
VDc O
utPut
SINgLE
3.3
5
12
15
DuAL
±5
±12
±15
MODELS
The Interpoint™ 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 185 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.
description
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 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 and 2
i
nhibit
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).
D
eSign
F
eatureS
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
Crane Aerospace & Electronics
Power Solutions – Interpoint Products
10301 Willows Rd. NE, Redmond, WA 98052
+1.425.882.3100 • 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.
c
urrent
S
hare anD
P
arallel
O
PeratiOn
Multiple SMFL converters may be used in parallel to drive a
common load (see Figure 2). Only single output models with
SENSE and SNS RTN can be used in the share mode. In this
mode of operation the load current is shared by two or three
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 14
SMFL Rev AA - 2012.03.19
Crane Aerospace & Electronics Power Solutions
SMFL Single and Dual DC/DC Converters
28 Volt input – 65 Watt
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, up to 95% of the total combined power ratings
of the SMFL converters is available at the load. Overload and
short circuit performance are not adversely affected during
parallel operation.
conversion Frequency (-55°c to 125°c)
• Free run mode 600 kHz typical
‣
525 kHz. min, 675 kHz max
operating conditions and characteristics
input Voltage range
• 16 to 40 VDC continuous
• 80 V for 50 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
derating output power/current
• Linearly from 100% at 125°C to 0% at 135°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
sync and inhibit (inh1, inh2)
sync
• Sync In
‣
Input frequency 525 to 675 Hz.
‣
Duty cycle 40% min, 60% max
‣
Active low 0.8 V max
‣
Active high 4.5 V min, 5 V max
‣
Referenced to input common
• Sync Out
‣
Referenced to input common
inhibit: inh1 and inh2
(do not apply a voltage to the inhibit pin)
• Converter Disabled (active low)
‣
INH1 referenced to input common
- Pull voltage to 0.8 V or below by connecting to ground or
other method.
- Inhibit pin source current, 10 mA max
‣
INH2 referenced to output common
- Pull voltage to 0.5 V or below by connecting to ground or
other method.
- Inhibit pin source current 5 mA max
• Converter Enabled (active high)
‣
Inhibit pin open or through an open collector
‣
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).
Case u has short, straight leads. Case V has longer leads
which are bent down.
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-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”.
• Available configurations: OO, HP, KP, HR, KR.
• See Screening Tables 1 and 2 for more information.
www.craneae.com/interpoint
Page 2 of 14
SMFL Rev AA - 2012.03.19
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
28V
Inhibit
Sync In
+
–
1
2
3
4
5
6
Positive Input
Input Common
TR1
INH1
Sync Out
Sync In
Pos. Sense
10
9
Sense Return
8
Output Common
7
Positive Output
MSTR/INH2
12
Slave
11
–
+
RL
REMOTE SENSE CONNECTION
28V
Inhibit
Sync In
+
–
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
RA
–
+
RL
OUTPUT VOLTAGE ADJUST CONNECTION
V
Out
i
ncreaSe
V
OltS
0.1
0.2
0.3
0.4
0.5
3.3 V
66
131
196
262
349
r
a
(O
hmS
)
5V
77
153
230
307
396
12 V
27
55
82
109
139
15 V
21
43
64
86
109
Notes:
1. When using remote sense for voltage
compensation or when using remote sense
for trim, the output will drift over temperature.
Contact Applications Engineering for more
information powerapps@crane-eg.com.
2. Do not exceed the maximum rated power.
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
7
Positive Output
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
Notes
1. No one converter may carry more than its maximum rated current.
2. Although up to 95% of the maximum current of paralleled converters is available, individual converter operation, load and layout may
affect the actual current shared. Contact Applications Engineering for more information powerapps@crane-eg.com.
F
igure
2: P
arallel
c
OnnectiOnS
– S
ingle
O
utPut
m
ODelS
www.craneae.com/interpoint
Page 3 of 14
SMFL Rev AA - 2012.03.19
Crane Aerospace & Electronics Power Solutions
SMFL Single and Dual DC/DC Converters
28 Volt input – 65 Watt
pin out
pin
1
2
3
4
5
6
7
8
9
10
11
12
single output
Positive Input
Triple (TR1)
Sync Out
Sync In
Input Common
Inhibit 1 (INH1)
Positive Input
Triple (TR1)
Sync Out
Sync In
dual output
pin
3
4
5
6
9
10
11
12
TR1
pins not in use
description
Inhibit 1 (INH1)
Sync Out
Sync In
Sense Return
Positive Sense
Slave
Master/Inhibit 2
(MSTR/INH2)
action
Leave unconnected
Leave unconnected
Connect to Input
Common
Input Common
Inhibit 1 (INH1)
Leave unconnected
Positive Output
Sense Return
Slave
Output Common
Positive Sense
Master/Inhibit 2
(MSTR/INH2)
Positive Output
Connect to appropriate
outputs
Output Common
Negative Output
No connection
Slave
Connect to appropriate
outputs
Leave unconnected
Leave unconnected
Master/Inhibit 2
(MSTR/INH2)
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 14
SMFL Rev AA - 2012.03.19
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
5962R9319202KxC
5962R9319302KxC
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 and 2 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 2 for more information.
www.craneae.com/interpoint
Page 5 of 14
SMFL Rev AA - 2012.03.19
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