F
EATURES
•
•
•
•
•
•
•
•
–55°C to +85°C operation
4 to 8 VDC input
Fully isolated
Opto-coupler feedback
Fixed frequency, 210 kHz typ.
Inhibit function
Indefinite short circuit protection
Up to 80% efficiency
DC/DC C
ONVERTERS
5 V
OLT
I
NPUT
MHL SERIES
15 WATT
MODELS
VDC O
UTPUT
DUAL
±12
±15
Size (max.): Non-flanged, case F4
1.950 x 1.350 x 0.505 inches (49.53 x 34.29 x 12.83 mm)
Flanged, case J5
2.720 x 1.350 x 0.505 inches (69.09 x 34.29 x 12.83 mm)
See Section B8, cases F4 and J5, for dimensions.
Weight:
57 grams typical
Screening: Standard or ES. See Section C2 for screening options, see Section
A5 for ordering information.
DESCRIPTION
The MHL Series™ of DC/DC converters offers either ±12 or ±15 volt
outputs in a single package. MHL converters offer the high efficiency
and wide input range of switching regulators with excellent load and
line regulation. Input and output grounds are isolated from one
another and from case ground. No external components are
required for operation. The units are built using thick-film hybrid
technology and are sealed in metal packages for military, aero-
space, and other high-reliability applications. Unscreened models
are sealed with solder and are guaranteed to pass a gross leak test
(maximum leak rate of 1 x 10
-3
atm.-cc/sec). Environmentally
screened models (/ES) are hermetically sealed with solder and will
pass a fine leak and gross leak test as described in Section C2.
The MHL converters employ pulse-width modulated switching regu-
lator techniques in the forward mode, with a nominal clock
frequency of 210 kHz. Isolation is achieved through the use of a
transformer in the forward power circuit and an opto-coupler in the
feedback/control loop. The full load output power (15 watts) is avail-
able over the input range of 4 to 8 VDC. Up to 14.3 watts can be
obtained from a single output up to a combined load of 15 watts.
The efficiency is high over the entire input voltage range and from
approximately 25% of full load to full load. This feature makes the
converters ideal for either battery or aircraft power applications.
An inhibit function is provided to allow power shut-down and start-
up from a logic input. An open circuit on the inhibit terminal produces
normal operation, and a low level disables the converter. Input
current in the inhibit mode is typically 20 mA. The converter features
a “soft-start” function which provides a controlled 20 millisecond
turn-on upon application of input power or inhibit release.
An input filter is incorporated in the unit to reduce input reflected
ripple current. Both outputs are indefinitely protected against short
circuits to ground or to one another by automatic current limiting
circuitry. This feature adjusts the converter’s output current, indefi-
nitely maintaining it below approximately 125% of the rated
maximum during a full short circuit condition.
The MHL Series of converters is rated to operate at full load at a
case temperature of 85°C, with the output power derated linearly to
zero at 115°C (0.5W/°C). Because of the unit’s 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 mate-
rial (PCB, copper sheet, heat sink, or Interpoint’s TMP accessory)
should be brought into contact with the converter’s baseplate.
When the MHL is used in applications requiring full-power operation
for extended periods of time, or in shock and vibration environ-
ments, it is highly recommended that the flange-mount case option
be used. This option provides improved thermal transfer capabilities
as well as mechanically secure mounting configuration.
V
=8 V
IN
Typical Performance Curve
84
V
=4 V
IN
82
80
V
=5 V
IN
EFFICIENCY (%)
78
76
74
72
70
2
4
6
8
10
12
14
16
18
OUTPUT POWER (WATTS)
MHL0515D Efficiency
F
IGURE
1
B4-17
INTERPOINT [ INTERPOINT CORPORATION COMPANY ]
