F
EATURES
鈥?鈥?5擄C to +85擄C operation
鈥?10 to 16 VDC input or
16 to 36 VDC input typical
鈥?Fully isolated
鈥?Opto-coupler feedback
鈥?Fixed frequency 125 kHz typical
鈥?Topology 鈥?Push-Pull Forward
鈥?Transient protection
50 V for up to 50 ms 28 Vin models
鈥?Inhibit function
鈥?Indefinite short circuit protection
鈥?Trimmable output on single models
鈥?Up to 83% efficiency
DC/DC C
ONVERTERS
12
AND
28 V
OLT
I
NPUT
MHE/MLP SERIES
20 WATT
MODELS
VDC O
UTPUT
SINGLE
DUAL
5
鹵12
12
鹵15
15
Size (max.): Non-flanged 2.125 x 1.125 x 0.495 MHE (case H6) inches
or 0.417 MLP (case H4)
(53.98 x 28.58 x 12.57 (MHE) or 10.59 (MLP) mm)
Flanged 2.910 x 1.125 x 0.495 MHE (case K7) inches
or 0.417 MLP (case K5)
(73.91 x 28.58 x 12.57 (MHE) or 10.59 (MLP) mm)
See Section B8, cases H4, H6, K5, and K7, for dimensions.
Weight:
50 grams typical
Screening: Standard or ES. See Section C2 for screening options, see
Section A5 for ordering information.
DESCRIPTION
The MHE Series鈩?and the MLP Series鈩?DC/DC converters offer
the high efficiencies associated with switching regulators, yet have
full isolation and the excellent regulation typical of linear regulators.
No external components are required for operation. MHE Series and
MLP Series converters are built using thick-film hybrid technology,
and are sealed in metal packages for military, aerospace, and other
high-reliability applications. Unscreened models are solder sealed
and are guaranteed to pass a gross leak test (maximum leak rate of
1 x 10
-3
atm.-cc/sec). Environmentally screened models are
hermetically sealed and are screened as described in Section C2.
The MHE Series and MLP Series converters are pulse-width modu-
lated switching regulators operating in the forward mode, with a
nominal switching frequency of 125 to 140 kHz. Isolation is achieved
through the use of a transformer in the forward power circuit, and an
optocoupler is used in the feedback/control loop. The full load output
power is available over the full input voltage range. Short-term tran-
sients of 50 volts will not impair normal operation for 28 volt input
models.
The efficiency is typically greater than 80% over the entire input
voltage range and from approximately 25% of full load to full load.
This feature makes the MHE/MLP Series converters ideal for either
battery or aircraft power applications.
An inhibit function is provided on MHE/MLP Series converters to
allow power shutdown and startup from a logic input. The unit is
inhibited when the inhibit input pin (pin 2) is connected to the input
common (pin 10). The open circuit voltage of the inhibit pin is 8 to
10 VDC for 12 V input models or 11 to 13 VDC for 28 V input
models. During inhibit, the input inhibit pin must sink approximately
1 mA. In the inhibit mode, converter output drops to less than 1 V
and the input current is typically 8 mA.
Automatic current limiting circuitry protects the MHE/MLP Series
converters against short circuits.
MHE/MLP Series converters are rated to operate at full load up to a
case temperature of 85擄C, with the output power derated linearly to
zero at 115擄C. Because of the unit鈥檚 high efficiency, heat sinking
requirements are minimized, but due consideration should be given
to removing self-generated heat when operating the device at
maximum ratings. To increase dissipation, heat conducting material
(PCB, copper sheet, heat sink, etc.) should be brought into contact
with the converter鈥檚 baseplate.
When the MHE/MLP Series converters are used in applications
requiring full power operation for extended periods of time, or in
shock and vibration environments, it is highly recommended that the
flange-mount option be used. This option provides improved thermal
transfer capabilities as well as a mechanically secure mounting
configuration.
B4-13
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