Crane Aerospace & Electronics Power Solutions
MFL Single and Dual DC/DC Converters
28 VOLT INPUT – 65 WATT
F
EATURES
•
•
•
•
•
•
•
•
•
•
•
•
•
•
–55° to +125°C operation
16 to 40 VDC input
Fully Isolated
Magnetic feedback
Fixed frequency, 600 kHz typical
Topology – Single Ended Forward
50 V for up to 120 ms transient protection
Inhibit (input & output side)
Sync function (in and out)
Output trim on single output models
Indefinite short circuit protection
Remote sense on single output models
Up to 87% efficiency / 43 W/in
3
Parallelable up to 148 watts
MODELS
VDC O
UTPUT
SINGLE
3.3
5
12
15
28
DUAL
±5
±12
±15
DESCRIPTION
The MFL Series™ 28-volt DC/DC converters are rated up to 65
watts of output power over a –55°C 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 output. Current sharing allows the units to be paralleled for
total power of up to 148 watts. The welded, hermetically sealed
package is only 3.005 x 1.505 x 0.400 inches, giving the series an
overall power density of up to 43 watts per cubic inch.
Other output voltages
available upon request,
including 2 V, 8 V and
54 V single.
I
NHIBIT
The MFL Series converters have two TTL compatible inhibit termi-
nals (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 application of intermediate voltages to these
pins (1.5 to 10.5 volts) should be avoided.
D
ESIGN
F
EATURES
The MFL Series converters are switching regulators that use a
quasi-square wave, single ended forward converter design with a
constant switching frequency of 600 kHz.
Isolation between input and output circuits is provided with a trans-
former in the forward path and a wide bandwidth magnetic coupling
in the feedback control loop. The MFL uses a unique dual loop feed-
back 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 regula-
tion is achieved through a wide-bandwidth magnetic feedback
circuit. The output on single MFL models can be trimmed (see
Figure 1 for voltage changes with different resistor values).
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 AND
P
ARALLEL
O
PERATION
Multiple MFL converters may be used in parallel to drive a common
load (see Figure 2). In this mode of operation the load current is
shared by two or three MFL converters. In current sharing mode,
one MFL 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). Figure 2 shows the
typical setup for two or three units in parallel. Note that synchro-
nizing the units together (though shown in the figure) 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).
When paralleled, 76% of the total combined power ratings of the
MFL converters are available at the load. Overload and short circuit
performance 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 D - 20060601
Crane Aerospace & Electronics Power Solutions
MFL Single and Dual DC/DC Converters
28 VOLT INPUT – 65 WATT
OPERATING CONDITIONS AND CHARACTERISTICS
Input Voltage Range
• 16 to 40 VDC continuous
• 50 V for 120 msec transient
Output Power
• 50 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 MFL2805S, MFL2805D)
Case Operating Temperature (Tc)
• –55°C to +125°C full power
• –55°C to +135°C absolute
Derate Output Power/Current
• Linearly from 100% at 125°C to 0% at 135°C
• MFL283R3S: linearly from 100% at 100°C to
80% at 125°C and 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
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
SYNC 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
Standard, ES, or /883 (Class H, QML). See “883, Class H, QML Products – Element Evaluation” and “883, Class H, QML Products – Environmental
Screening” for more information.
www.craneae.com
Page 2 of 13
Rev D - 20060601
Crane Aerospace & Electronics Power Solutions
MFL Single and Dual DC/DC Converters
28 VOLT INPUT – 65 WATT
MODEL NUMBERING KEY
MFL
Base Model
Input Voltage
Output Voltage
Number of Outputs
(S = single, D = dual)
Screening
(Standard screening has no designator
in this position.)
28 05 S / ES
SMD NUMBERS
S
TANDARD
M
ICROCIRCUIT
D
RAWING
(SMD)
IN PROCESS
5962-9316301HXC
5962-9316201HXC
5962-9316101HXC
IN PROCESS
5962-9319101HXC
5962-9319201HXC
5962-9319301HXC
MFL S
ERIES
S
IMILAR
P
ART
MFL283R3S
MFL2805S/883
MFL2812S/883
MFL2815S/883
MFL2828S/883
MFL2805D/883
MFL2812D/883
MFL2815D/883
For exact specifications for an SMD product, refer to the
SMD drawing. SMDs can be downloaded from:
http://www.dscc.dla.mil/programs/smcr
Model Selection
MFL28
Base model
Vout value
number of outputs
screening
Choose one from each of the following rows
Vout value
Number of outputs
Screening
for singles: 3R3, 5, 12, 15, 28
“R” = decimal point, 3R3 = 3.3VDC
for duals: 5, 12, 15
S (single) or D (dual)
standard screening, leave blank
/ES (ES screening), /883 (Class H, QML)
www.craneae.com
Page 5 of 13
Rev D - 20060601
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