MODELS

VDC O

UTPUT

B2-47

SINGLE

12
15
18

DUAL

±5

±12
±15

DESCRIPTION

The MHD SeriesTM of DC/DC converters offers up to 20 watts of
output power over the full military temperature range with up to 84%
efficiency. Thick-film hybrid techniques provide military/aerospace
reliability levels and optimum miniaturization. The MHD Series
power density rating is up to 21 watts/in

MHD converters are packaged in hermetically sealed metal cases,
making them ideal for use in military, aerospace and other high reli-
ability applications. Units are available with standard screening,
"ES" screening, or fully compliant SMD versions (see Section C2 for
screening conditions).

ONVERTER

ESIGN

The MHD converters are constant frequency, pulse-width mod-
ulated switching regulators which use a quasi-square wave, single
ended, forward converter design. Tight load regulation (5 mV
typical) is maintained via wide bandwidth magnetic feedback and,
on single output models, through use of remote sense. On dual
output models, the positive output is independently regulated and
the negative output is cross regulated through the use of tightly
coupled magnetics and shunt regulators.

Indefinite short circuit protection and overload protection are
provided by a constant current-limit feature. This protective system
senses current in the converter's secondary stage and limits it to
approximately 115% of the maximum rated output current.

MHD converters are provided with internal filtering capacitors that
help reduce the need for external components in normal operation.
For systems that require compliance with MIL-STD-461C's CE03
standard, Interpoint offers filter/transient suppression modules
(including the FMC-461, FMD-461 and FM-704A series filters) which
will result in compliance. Contact your Interpoint representative for
further details.

YNCHRONIZATION

The MHD offers a synchronization feature that allows the designer
to match the switching frequency of the converter to the frequency
of the system clock. In free-run (unsynchronized) mode, the MHD
unit switches at 625 kHz (nominal). In sync mode, the converter will
run at any frequency between 500 kHz and 675 kHz. The sync
control operates with a quasi-TTL signal at any duty cycle between
40% and 60%.

Synchronizing the converter with the system clock allows the
designer to confine switching noise to clock transitions, minimizing
interference and reducing the need for filtering. The sync pin should
be connected to input common pin when not in use.

IDE

OLTAGE

ANGE

The MHD converters are designed to provide full power operation
over a full 16 to 40 VDC voltage range. Operation below 16 volts,
including MIL-STD-704E emergency power conditions is possible
with derated power. Refer to the low line dropout graph (Figure 15)
for details.

MPROVED

YNAMIC

ESPONSE

The MHD feed-forward compensation system provides excellent
dynamic response and noise rejection. Audio rejection is typically 50
dB. The min. to maximum step line transient response is typically
less than 4%.

NHIBIT

UNCTION

MHD converters provide an inhibit terminal that can be used to
disable internal switching, resulting in no output and very low
quiescent input current. The converter is inhibited when a TTL
compatible low (

0.8 V) is applied to the inhibit pin. The unit is

enabled when the pin, which is internally connected to a pull-up
resistor, is left unconnected or is connected to an open-collector
gate. The open circuit output voltage associated with the inhibit pin
is 9 to 11 V. In the inhibit mode, a maximum of 8 mA must be sunk
from the inhibit pin.

DC/DC C

ONVERTERS

28 V

OLT

NPUT

MHD SERIES

20 WATT

EATURES

· 55° to +125°C operation
· 16 to 40 VDC input
· Fully Isolated
· Magnetic feedback
· Fixed frequency
· Topology Single Ended Forward
· 50 V for up to 50 ms

transient protection

· Inhibit and synchronization functions
· Indefinite short circuit protection
· Up to 84% efficiency, 21 watts/in

Size (max.): Non-flanged, case H2

2.125 x 1.125 x 0.400 inches (53.98 x 28.58 x 10.16 mm)

Flanged case, K3

2.910 x 1.125 x 0.400 inches (73.91 x 28.58 x 10.16 mm)

See Section B8, cases H2 and K3 for dimensions.

Weight:

52 grams max., flanged 55 grams max.

Screening: Standard, ES, or 883 (Class H). See Section C2 for screening

options, see Section A5 for ordering information.

TYPICAL CHARACTERISTICS

SYNC AND INHIBIT

RECOMMENDED OPERATING CONDITIONS

ABSOLUTE MAXIMUM RATINGS

Input Voltage

· 16 to 40 V

Output Power

· 15 to 20 watts depending on model

Lead Soldering Temperature (10 sec per lead)

· 300°C

Storage Temperature Range (Case)

· 65°C to +150°C

B2-48

MHD SERIES
20 WATT

DC/DC C

ONVERTERS

Output Voltage Temperature Coefficient

· 100 ppm/°C typical

Input to Output Capacitance

· 50 pF typical

Current Limit

· 115% of full load typical

Isolation

· 100 megohm minimum at 500 V

Audio Rejection

· 50 dB typical

Conversion Frequency

· Free run mode 625 kHz typical

550 kHz. min, 650 kHz max

· External sync range 500 to 675 kHz

Inhibit Pin Voltage (unit enabled)

· 9 to 11 V

Input Voltage Range

· 16 to 40 VDC continuous
· 50 V for up to 50 msec transient

Case Operating Temperature (Tc)

· 55°C to +125°C Full power
· 55°C to +135°C Absolute

Derating Output Power/Current

· Linearly from 100% at 125°C to 0% at 135° C

Sync (500 to 675 kHz)

· Duty cycle 40% min, 60% max
· Logic low 0.8 V max, 0.0 V min
· Logic high 4.0 V min, 10 V max
· Referenced to input common
· If not used, connect to input common

Inhibit: TTL Open Collector

· Logic low (output disabled)

Logic low voltage

0.8 V

Inhibit pin current 8.0 mA max

· Referenced to input common
· Logic high (output enabled)

Open collector

SINGLE OUTPUT MODELS

MHD2805S

MHD2812S

MHD2815S

MHD2818S

PARAMETER

CONDITION

MIN TYP MAX

MIN

TYP MAX

MIN

TYP MAX

MIN

TYP MAX

UNITS

OUTPUT VOLTAGE

4.95

5.00

5.05

11.88 12.00 12.12

14.85 15.00 15.15

17.82 18.00 18.18

VDC

OUTPUT CURRENT

= 16 to 40 VDC

1.67

1.33

1.11

OUTPUT POWER

= 16 to 40 VDC

OUTPUT RIPPLE

10 kHz 2 MHz

mV p

VOLTAGE

Tc = 55°C TO +125°C

LINE REGULATION

Vin = 16 to 40 VDC

Tc = 55°C TO +125°C

LOAD REGULATION

NO LOAD TO FULL

Tc = 55°C TO +125°C

INPUT VOLTAGE

CONTINUOUS

VDC

NO LOAD TO FULL

TRANSIENT 50 ms

INPUT CURRENT

NO LOAD

FULL LOAD

0.70

0.87

0.85

INHIBITED

INPUT RIPPLE

10 kHz 10 MHz

CURRENT

Tc = 55°C TO +125°C

mA p-p

EFFICIENCY

LOAD FAULT

SHORT CIRCUIT

SHORT CIRCUIT TO

POWER DISSIPATION

FULL LOAD

RECOVERY

1, 3

1.4

STEP LOAD RESP.

50% 100% 50%

±200 ±300

±250 ±400

±350 ±500

±600

TRANSIENT

10% 100%

400 600

600 1000

800 1200

mV pk

100% 10%

+350 +600

+500 +750

+600 +1000

50% 100% 50%

200

RECOVERY

10% 100%

600

150

300

250

500

µs

100% 10%

200

600

250

500

250

500

STEP LINE RESP.

16 40 16 VDC

TRANSIENT

±200 ±300

±400 ±500

±500 ±600

±600

mV pk

RECOVERY

300

µs

START-UP

DELAY

1.4

OVERSHOOT

FULL LOAD

120

150

180

mV pk

NO LOAD

250

120

600

150

750

Electrical Characteristics:25C Tc, 28 VDC Vin, 100% load, free run, unless otherwise specified.

Notes
1. Tc = 55°C to +125°C
2. Operation is limited below 16V (see Figure 15).
3. Indefinite short circuit protection not guaranteed above 125°C case.

4. Recovery time is measured from application of the transient to point at which

Vout is within 1% of final value.

5. Transition time

10 µs.

DUAL OUTPUT MODELS

MHD2805D

MHD2812D

MHD2815D

PARAMETER

CONDITIONS

MIN TYP MAX

MIN

TYP

MAX

MIN

TYP

MAX

UNITS

OUTPUT VOLTAGE

OUT

4.95

5.00

5.05

11.88

12.00

12.12 14.85

15.00

15.15

VDC

OUT

4.925

5.00

5.075

11.82

12.00

12.18

14.77

15.00

15.23

OUTPUT CURRENT

1,2

= 16 TO 40 VDC

0.30

3.0

0.13

1.25

0.10

1.00

OUTPUT POWER

1,2

= 16 TO 40 VDC

OUTPUT RIPPLE

10 kHz - 2 MHz

mV p-p

VOLTAGE +/ V

OUT

Tc = 55°C TO +125°C

120

LINE REGULATION

Tc = 55°C

OUT

= 16 TO 40 VDC

TO +125°C

OUT

100

150

180

LOAD REGULATION

Tc = 55°C

OUT

NO LOAD TO FULL

TO +125°C

OUT

100

150

180

CROSS REGULATION

SEE NOTE 4

8.3

EFFECT ON V

OUT

SEE NOTE5

INPUT VOLTAGE

CONTINUOUS

VDC

NO LOAD TO FULL

TRANSIENT 50 ms

INPUT CURRENT

NO LOAD

FULL LOAD

0.70

0.88

0.86

INHIBITED

INPUT RIPPLE

CURRENT

10 kHz - 10 MHz

mA p-p

EFFICIENCY

LOAD FAULT

POWER DISSIPATION

SHORT CIRCUIT

RECOVERY

1, 7

1.4

5.0

1.4

5.0

1.4

5.0

STEP LOAD TRANSIENT

RESPONSE ± V

OUT

50 100 50%

±200

±300

±150

±300

±200

±400

mV pk

10 100 10%

±400

±600

±200

±400

±300

±500

RECOVERY

50 100 50%

100

200

100

200

100

200

10 100 10%

400

600

100

200

250

µs

STEP LINE

16 40 16 V

RESPONSE ± V

OUT

TRANSIENT

±200

±400

±200

±400

±500

mV pk

RECOVERY

300

µs

STARTUP

DELAY

1.4

OVERSHOOT

120

150

mV pk

NO LOAD

250

120

600

150

750

B2-49

MHD SERIES

20 WATT

DC/DC C

ONVERTERS

Electrical Characteristics: 25°C Tc, 28 VDC Vin, 100% load, free run, unless otherwise specified.

Notes
1. Tc = 55°C to +125°C.
2. Up to 90% of the total output current/power is available from either output

The minimum load on the positive output is 10% of full load.

3. Operation is limited below 16 V (see Figure 15).
4. Effect on the negative output under the following conditions:

+Pout 20% to 80%; Pout 80% to 20%

5. Effect on the negative output under the following conditions:

+Pout 50%; Pout 10% to 50%

6. Indefinite short circuit protection not guaranteed above 125°C case.
7. Recovery time is measured from application of the transient to point at which

Vout is within 1% of final value.

8. Transition time

10 µs.

SMD NUMBERS

TANDARD

ICROCIRCUIT

MHD S

IMILAR

RAWING

(SMD)

ODEL

UMBER

NON-FLANGED CASE

59629465501HXC

MHD2805S/883

59629465601HXC

MHD2812S/883

59629465701HXC

MHD2815S/883

59629465801HXC

MHD2818S/883

59629465901HXC

MHD2805D/883

59629466001HXC

MHD2812D/883

59629466101HXC

MHD2815D/883

FLANGED CASE

59629465501HZC

MHD2805SF/883

59629465601HZC

MHD2812SF/883

59629465701HZC

MHD2815SF/883

59629465801HZC

MHD2818SF/883

59629465901HZC

MHD2805DF/883

59629466001HZC

MHD2812DF/883

59629466101HZC

MHD2815DF/883

B2-50

MHD SERIES
20 WATT

DC/DC C

ONVERTERS

MODEL NUMBERING KEY

MHD 28 12 S F / 883

Base Model

Input Voltage

Output Voltage

Screening

Number of Outputs

(S = single, D = dual)

Case Option

(Non-flanged case has no designator in
this position)

(Standard screening has no designator
in this position.)

PIN OUT

Pin

Single Output

Dual Output

Positive Input

Inhibit

No Connection

Positive Output

Output Common

Positive Output

Negative Output

Case Ground

Sync Input

Input Common

Dot on top of cover indicates pin one.

BOTTOM VIEW

MHD

FLANGED AND NON-FLANGED

Dotted line outlines flanged package option.

For exact specifications for an SMD product, refer to the SMD drawing. See
Section A3, SMDs, for more information.

See Section B8, cases H2 and K3 for dimensions.

IGURE

1: P

B2-51

MHD SERIES

20 WATT

DC/DC C

ONVERTERS

Typical Performance Curves: 25°C Tc , 28 VDC Vin, 100% load, free run, unless otherwise specified.

IGURE

16V

40V

28V

Output Power (Watts)

MHD2805S Efficiency

Efficiency (%)

IGURE

16V

28V

40V

Output Power (Watts)

MHD2812S Efficiency

Efficiency (%)

IGURE

16V

28V

40V

Output Power (Watts)

MHD2815S Efficiency

Efficiency (%)

40V

16V

Output Power (Watts)

MHD2812D Efficiency

Efficiency (%)

28V

40V

28V

16V

Output Power (Watts)

MHD2815D Efficiency

Efficiency (%)

100

0.1

100

Frequency (kHz)

MHD Series Audio Rejection

Attenuation (dB)

100 mV/div

15 W to 7.5 W

7.5 W to 15 W

s/div

50% to 100% to 50%

MHD2805S Step Load Response

200mV/div

15 W to 1.5 W

1.5 W to 15 W

s/div

10% to 100% to 10%

MHD2805S Step Load Response

IGURE

s/div

(16 TO 40V)

MHD2805S Step Line Response

20 mV/div

20 V/div

Vin

Vout

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: MHD2818SF/883

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: MHD2818SF/883