Crane Aerospace & Electronics Power Solutions
MFLHP Single and Dual DC/DC Converters
28 VOLT INPUT – 100 WATT
FEATURES
• -55° to +100°C operation
• 19 to 40 VDC input
• Fully Isolated
• Magnetic feedback
• Fixed frequency, 600 kHz typical
• Topology – Single Ended Forward
• 80 V for up to 50 ms transient protection
• Inhibit function – input and output
• Sync function – input and output
• Output trim on single output models
• Indefinite short circuit protection
• Remote sense on single output models
• Up to 87% efficiency
• Parallelable up to 228 watts
MODELS
VDC OUTPUT
SINGLE
DUAL
5
12
15
±5
±12
±15
DESCRIPTION
The MFLHP Series™ 28 volt DC/DC converters are rated up to
100 watts output power over a -55° to +100°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 228 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 67 watts per cubic inch.
resulting in a very low quiescent input current. A logic low (<0.8
volts) is required between INH1 (pin 4) and Input Common (pin
2) to inhibit the converter. A logic low (<0.5 volts) is required
between INH2 (pin 12) and Output Common (pin 8) to inhibit the
converter. The application 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
The MFLHP 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
transformer in the forward path and wide bandwidth magnetic
coupling in the feedback control loop. The MFLHP Series uses a
unique dual loop feedback technique that controls output current
with an inner feedback loop and 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.
Tight load regulation is achieved through a wide-bandwidth
magnetic feedback circuit. The output voltage on single MFLHP
models can be easily trimmed by adding an external resistor.
(See Figure 1 for voltage changes with different resistor values.)
C
URRENT
S
HARING AND
P
ARALLEL
O
PERATION
Multiple MFLHP converters may be used in parallel to drive a
common load (see Figure 3). In this mode of operation the load
current is shared by two or three MFLHP converters. In current
sharing mode, one MFLHP 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 3 shows the typical setup for two or
three units in parallel. Note that synchronizing 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
MFLHP converters are available at the load. Overload and short
circuit performance are not adversely affected during parallel
operation.
I
NHIBIT
The MFLHP Series converters have two inhibit terminals (INH1
and INH2) that can be used to disable power conversion,
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 11
Rev D - 20070703
CRANE [ Crane Aerospace & Electronics. ]
