F
EATURES
• –55° to +125°C operation
• 16 to 40 VDC input
(19 to 40 VDC for 15 volt outputs)
• Fully Isolated
• Optocoupler feedback
• Fixed frequency 600 kHz typical
• Forward converter topology
• 50 V for up to 50 ms transient protection
• Inhibit function
• Indefinite short circuit protection
• Up to 83% efficiency, 22 W/in
3
DC/DC C
ONVERTERS
28 V
OLT
I
NPUT
MHF SERIES
12 WATT
MODELS
VDC O
UTPUT
SINGLE
5
12
15
DUAL
±12
±15
Size (max.): 1.460 x 1.130 x 0.330 inches (37.08 x 28.70 x 8.38 mm)
See Section B8, case E1 for dimensions.
Weight:
21 grams typical.
Screening: Standard or ES.
See section C2 for screening options.
DESCRIPTION
The MHF Series™ of DC/DC converters offer up to 12 watts of
power from single or dual outputs in a single package over a the full
military temperature range. Thick film hybrid manufacturing tech-
nology produces high levels of miniaturization, giving the MHF
Series converters a low profile (0.330 inch), small board area (1.65
square inches), and high power density (22 watt/in
3
).
The parts are packaged in hermetically sealed steel enclosures,
making them ideal for use in military, aerospace, and high reliability
industrial applications.
elements on both the input and output to help reduce the need for
external components. For information about filtering to meet MIL-
STD-461’s CE03 test, contact your Interpoint representative.
W
IDE
V
OLTAGE
R
ANGE
The MHF Series is designed to provide full power operation over the
input voltage range of 16 to 40 volts. The 15 volt models provide a
19 to 40 volt range. Operation below 16 volts (or 19 volts for the 15
volt models), including operation in MIL-STD-704E emergency
power conditions, is possible with derated output power. Please
refer to the low line drop-out graphs, Figures 9 and 10.
D
ESIGN
M
ETHODOLOGY
The MHF converters are switching regulators which use a quasi-
square wave, single ended forward converter design with a nominal
switching frequency of 600 kHz. Isolation between input and output
circuits is provided with a transformer in the forward power loop and
a temperature insensitive optical link in the feedback control loop.
Output regulation is accomplished with constant frequency pulse
width modulation. Both line and load regulation are typically within
10 mV.
On dual output models, the positive output is independently regu-
lated and the negative output is cross-regulated. Figures 7 and 8
illustrate what effects load changes have on the negative output.
Indefinite short circuit protection and overload protection are
provided by sensing output load current and restricting the output
current to approximately 125% of full load output current. Since the
output current is sensed in the secondary stage, the result is a
predictable, constant output current control with no foldback char-
acteristics. MHF converters are provided with internal filtering
M
ILITARY
T
EMPERATURE
R
ANGE
The MHF Series provides full power operation at case temperatures
from –55°C up to +125°C. All 12 and 15 volt models in both single
and dual output configurations provide full power operation at
+125°C with derated power to 135°C. The +5 volt model provides
full power at 110°C derated to 0% at 130°C. Depending on operating
levels, air flow, and ambient temperature; heat sinking may be
required.
I
NHIBIT
F
EATURE
An inhibit terminal is provided that can be used to disable internal
switching, resulting in a very low quiescent input current. An open
collector TTL compatible low (≤0.8V) is required to control the inhibit
function. This level may be supplied by an open collector gate since
the inhibit pin is provided with an internal pull-up resistor.
B2-77
MHF SERIES
12 WATT
ABSOLUTE MAXIMUM RATINGS
Input Voltage
• 16 to 40 VDC (19 to 40 VDC 15 volt output)
Output Power
• 12 watts (10 watts MHF2805S)
Lead Soldering Temperature (10 sec per lead)
• 300°C
Storage Temperature Range (Case)
• –55°C to +135°C
DC/DC C
ONVERTERS
INHIBIT
Inhibit TTL Open Collector
• Logic low (output disabled)
Logic low 0.8 V max
Inhibit pin current 4 mA max
• Referenced to input common
• Logic high (output enabled)
Open collector
TYPICAL CHARACTERISTICS
Output Voltage Temperature Coefficient
• 150 ppm/°C, typical
Input to Output Capacitance
• 50 pF, typical
Current Limit
• 125% of full load, typical
Isolation
• 100 megohm minimum at 500 V
Conversion Frequency
• 600 kHz typical
Inhibit Pin Voltage (unit enabled)
• 8 to 11 V
RECOMMENDED OPERATING CONDITIONS
Input Voltage Range
• 16 to 40 VDC continuous
• 19 to 40 VDC 15 volt outputs continuous
• 50 V for 50 msec transient
Case Operating Temperature (Tc)
• –55°C to +125°C full power
• –55°C to +110°C full power for MHF2805S
• –55°C to +135°C absolute
• –55°C to +130°C absolute for MHF2805S
Derating Output Power/Current
• Linearly from 100% at 125°C to 0% at 135°C
• Linearly from 100% at 110°C to 0% at 130°C
for MHF2805S
Electrical Characteristics: 25°C Tc, 28 VDC Vin, 100% load, unless otherwise specified.
SINGLE OUTPUT MODELS
PARAMETER
OUTPUT VOLTAGE
OUTPUT CURRENT
OUTPUT POWER
OUTPUT RIPPLE
LINE REGULATION
LOAD REGULATION
INPUT VOLTAGE
MIN. TO MAX. V
IN
10 kHz to 2 MHz
MIN. TO MAX. V
IN
NO LOAD TO FULL
CONTINUOUS
TRANSIENT 50 ms
INPUT CURRENT
NO LOAD
FULL LOAD
INHIBITED
INPUT RIPPLE
CURRENT
EFFICIENCY
LOAD FAULT
1
POWER DISSIPATION
OVERLOAD
SHORT CIRCUIT
START-UP
DELAY
—
—
—
—
–
180
5
3.5
300
—
—
—
—
—
80
5
2.8
200
—
—
—
—
—
150
5
2
250
ms
W
10 kHz TO 2 MHz
—
74
135
77
180
—
—
77
150
81
200
—
—
80
150
83
220
—
mA p-p
%
CONDITIONS
MIN
4.95
—
—
—
—
—
16
—
—
—
—
MHF2805S
TYP
5.0
—
—
40
10
10
28
—
20
—
2
MAX
5.05
2.0
10
60
50
50
40
50
30
483
3
MIN
11.88
—
—
—
—
—
16
—
—
—
—
MHF2812S
TYP
12
—
—
30
10
10
28
—
20
—
2
MAX
12.12
1.0
12
60
50
50
40
50
30
557
3
MHF2815S
MIN
14.85
—
—
—
—
—
19
—
—
—
—
TYP
15
—
—
25
10
10
28
—
20
—
2
MAX
15.15
0.8
12
50
50
50
40
50
30
535
3
mA
UNITS
VDC
A
W
mV p-p
mV
mV
VDC
V
Notes
1. Indefinite short circuit protection not guaranteed above 125°C case temperature (110°C case for MHF2805S).
B2-78
DC/DC C
ONVERTERS
DUAL OUTPUT MODELS
PARAMETER
OUTPUT VOLTAGE
CONDITION
+V
OUT
– V
OUT
OUTPUT CURRENT
1, 2
OUTPUT POWER
2
+V
OUT
– V
OUT
TOTAL
OUTPUT RIPPLE
VOLTAGE
LINE REGULATION
MIN. TO MAX. V
IN
LOAD REGULATION
NO LOAD TO FULL
CROSS REGULATION
+V
OUT
20% TO 80% LOAD
3
50% LOAD
4
INPUT VOLTAGE
NO LOAD TO FULL
INPUT CURRENT
CONTINUOUS
TRANSIENT 50 ms
NO LOAD
FULL LOAD
INHIBITED
10 kHz TO 2 MHz
—
—
—
16
—
—
—
—
—
78
POWER DISSIPATION
SHORT CIRCUIT
OVERLOAD
START-UP
DELAY
—
—
—
—
—
150
2.8
5
250
—
—
—
—
—
150
2
5
250
ms
W
5
5
4
28
—
25
—
1.9
175
81
50
10
5
40
50
35
550
3
240
—
—
—
—
19
—
—
—
—
—
80
10
4
3
28
—
25
—
1.9
175
83
50
8
5
40
50
35
536
3
240
—
VDC
V
mA
mV
%
+V
OUT
—
5
50
—
5
50
mV
10 kHz TO 2 MHz
MIN
11.88
11.82
—
—
—
—
—
MHF2812D
TYP
MAX
12.0
12.0
0.5
—
—
—
30
12.12
12.18
1.0
10.8
10.8
12
60
MIN
MHF2815D
TYP
MAX
15.0
15.0
0.4
—
—
—
30
15.15
15.23
0.8
10.8
10.8
12
60
mV p-p
W
A
UNITS
VDC
14.85
14.77
—
—
—
—
—
MHF SERIES
12 WATT
Electrical Characteristics: 25°C Tc, 28 VDC Vin, 100% load, unless otherwise specified.
INPUT RIPPLE
CURRENT
EFFICIENCY
LOAD FAULT
5
mA p-p
%
Notes
1. Applies to both outputs.
2. Maximum combined output power is 12 watts. A maximum of 90% is avail-
able from either output.
3. 20% to 80% load on the positive output and 80% to 20% on the negative
output. See Figure 8.
4. 50% load on the positive output and 50% to 20% load on the negative output.
50% load on the negative output and 50% to 20% load on the positive output.
See Figure 7.
5. Indefinite short circuit protection not guaranteed above 125°C case temper-
ature.
PIN OUT
Pin
1
2
3
4
5
6
7
8
Single Output
Inhibit
No connection
Output Common
Positive Output
No connection
Case Ground
Input Common
Positive Input
Dual Output
Inhibit
Positive Output
Output Common
Negative Output
No connection
Case Ground
Input Common
Positive Input
Squared corner and dot on
top of cover indicate pin one.
MODEL NUMBER KEY
MHF
Base Model
Input Voltage
Output Voltage
Number of Outputs
(S = single, D = dual)
Screening
(Standard screening has no designator
in this position.)
28 12
D / ES
1
2
3
4
5
BOTTOM VIEW
MHF
8
7
6
See Section B8, case E1, for dimensions.
F
IGURE
1: P
IN
O
UT
B2-79
MHF SERIES
12 WATT
90
DC/DC C
ONVERTERS
90
16V
Typical Performance Curves: 25°C Tc , 28 VDC Vin, 100% load, unless otherwise specified.
90
19V
80
16V
80
80
Efficiency (%)
Efficiency (%)
40V
70
28V
60
70
40V
28V
Efficiency (%)
40V
70
28V
60
60
50
2
4
6
8
10
12
14
50
2
4
6
8
10
12
14
50
2
4
6
8
10
12
14
Output Power (Watts)
Output Power (Watts)
Output Power (Watts)
MHF2805S Efficiency
MHF2812S Efficiency
MHF2815S Efficiency
F
IGURE
2
90
16V
F
IGURE
3
90
F
IGURE
4
Negative Output Voltage Change (%)
10
8
6
4
2
0
2
–4
–6
–8
–10
0
10
2
30
40
50
2812D
2815D
2812D
19V
80
80
40V
Cond. A
Efficiency (%)
Efficiency (%)
40V
70
28V
70
28V
60
60
Cond. B
50
50
2
4
6
8
10
12
14
2
4
6
8
10
12
14
Output Power (Watts)
Output Power (Watts)
MHF2812D Efficiency
MHF2815D Efficiency
Output Load (%)
Condition A: 50% Load Pos. Vout, 50% to 20% Neg. Vout
Condition B: 50% Load Neg. Vout, 50% to 20% Pos. Vout
MHF Negative Output Voltage
Cross Regulation
F
IGURE
5
20
19
18
F
IGURE
6
19
18
2815S
F
IGURE
7
Negative Output Voltage Change (%)
15
Input Voltage (Volts)
Input Voltage (Volts)
10
5
0
–5
–10
–15
–20
0
20
40
60
80
100
2812D
2815D
17
16
15
14
13
12
11
2
4
17
2815D
16
15
14
13
12
2812D
2812S
2805S
6
8
10
12
14
11
Output Load (%)
Positive Output 20% to 80% Load
Negative Output 80% to 20% Load
2
4
6
8
10
12
14
Output Power (Watts)
50 mV Drop
Output Power (Watts)
50 mV Drop
MHF Dual Negative Output Voltage
Cross Regulation
MHF Single Low Line Dropout
MHF Dual Low Line Dropout
F
IGURE
8
F
IGURE
9
F
IGURE
10
B2-80
218211-001-DTS Rev A
DQ# 1011
All technical information is believed to be accurate, but no responsibility is
assumed for errors or omissions. Interpoint reserves the right to make changes in
products or specifications without notice. MHF Series is a trademark of Interpoint.
Copyright © 1992 - 1999 Interpoint. All rights reserved.
CASE E
C
ASES
Squared corner and dot on top
of case indicate pin one.
Materials
Header Cold Rolled Steel/Nickel/Gold
Cover Kovar/Nickel
(SMHF Series
Cold Rolled Steel/Nickel/Gold)
Pins
#52 alloy/Gold
compression glass seal
Case dimensions in inches (mm)
Tolerance
±0.005
(0.13) for three decimal places
±0.01
(0.3) for two decimal places
unless otherwise specified
CAUTION
Heat from reflow or wave soldering may damage
the device. Solder pins individually with heat
application not exceeding 300°C for 10 seconds
per pin.
CASE E
BOTTOM VIEW
See Figures 16 – 18
for pin configurations.
1.130 max
(28.70)
1.460 max
(37.08)
F
IGURE
15: C
ASE
E M
AXIMUM
D
IMENSIONS
BOTTOM VIEW CASE E1
MHF+ Series Single and Dual: Screening – Standard, ES, or 883
MHF Series and LIM5050 Module: Screening – Standard or ES
SMHF Series Single and Dual and SLIM5050 Module:
Screening – Space Standard, H, or K
HR120 Series: No screening options
Seam Seal
Projection Weld
Squared corner and dot on top
of case indicate pin one.
0.960
(24.38)
0.030 dia.
(0.76)
1
2
3
4
5
0.160
(4.06)
0.000
0.330 max
(8.38)
0.000
0.25 (6.35)
0.330 max
(8.38)
0.000
0.25 (6.35)
0.000
8
7
6
0.205
(5.21)
F
IGURE
16: C
ASE
E1
Note: Although every effort has been made to render the case drawings at actual size, variations in the printing process may cause some distortion. Please refer
to the numerical dimensions for accuracy.
B8-10
0.505
(12.83)
0.705
(17.91)
0.905
(22.99)
1.105
(28.07)
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