PD-94437D
M3H-SERIES
HYBRID - HIGH RELIABILITY
RADIATION TOLERANT
DC/DC CONVERTER
Description
The M3H-Series of DC/DC converters are radiation
tolerant, high reliability devices designed for moderate
radiation environments such as those encountered by
low earth orbit satellites and launch vehicles. For higher
radiation environments, the M3G-Series of DC/DC
converters is recommended. System upgrades to higher
radiation tolerance applications can be easily
accommodated with the M3G-Series converters because
they have the same mechanical outline and are pin
compatible. For physically smaller, lower output power
single and dual output applications the M3L-Series of
DC/DC converters are recommended. Features of the
M3H-Series include up to 40 watt output power, small
size, low weight and a high tolerance to total ionizing
dose, single event effects and environmental stresses
such as temperature extremes, mechanical shock, and
vibration. All components are fully derated to meet the
requirements of MIL-STD-975 and MIL-STD-1547.
Extensive documentation including Radiation
Susceptibility, Thermal Analysis, Stress Analysis and
MTBF are available.
The converters incorporate a fixed frequency single
forward topology with magnetic feedback and an internal
EMI filter. These converters are capable of meeting the
conducted emissions and conducted susceptibility
requirements of MIL-STD-461C without any additional
components. All models include an external inhibit port
and have an adjustable output voltage. They are
enclosed in a hermetic 3.0" x 2.5" x 0.445" steel package
and weigh less than 125 grams. The package utilizes
rugged ceramic feed-through copper core pins and is
sealed using parallel seam welding.
Manufactured in a facility fully qualified to MIL-PRF-
38534, these converters are fabricated utilizing DSCC
qualified processes. For available screening options,
refer to device screening table in the data sheet.
+28V Input, Single/Dual Output
M3H
Features
n
Total Dose > 25K Rad(Si)
n
SEE Hardened to LET up to 37 MeV
.
cm
2
/mg
n
Internal EMI filter; Converter Capable of
meeting MIL-STD-461C CE03 and CS01
n
Low Weight, < 125 grams
n
Magnetically Coupled Feedback
n
18V to 50V Input Range ( 50V, 70V, and
120V Models Available)
n
Up to 40W Output Power
n
Single and Dual Output Models Include
3.3, 5, 5.2, 12, 15,
±
5,
±
12,
±
15V
n
High Efficiency - to 82%
n
-55°C to +125°C Operating Temperature Range
n
100M
Ω
@ 500VDC Isolation
n
Under-Voltage Lockout
n
Short Circuit and Overload Protection
n
Adjustable Output Voltage
n
External Inhibit
n
1,500,000 Hour MTBF
Applications
n
n
Low Earth Orbit Satellites (LEO)
Launch Vehicles
Non-flight versions of the M3H-Series converters
are available for system development purposes.
Variations in electrical specifications and
screening to meet custom requirements can be
accommodated. Consult IR Santa Clara for special
requirements.
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1
09/8/06
M3H-SERIES
Circuit Description
The M3H-Series converters utilize a single forward
topology with resonant reset. The nominal switching
frequency is 500kHz. Electrical isolation and tight
output regulation are achieved through the use of a
magnetically coupled feedback. Voltage feed-forward
provides high line rejection.
An internal EMI filter allows the converter to meet the
conducted emissions requirements of MIL-STD-461C
on the input power leads. A two-stage output filter
reduces the typical output ripple to less than 20mV
peak-to-peak.
Output current is limited under any load fault condition
to approximately 125% of rated. An overload
condition causes the converter output to behave like
a constant current source with the output voltage
dropping below nominal. The converter will resume
normal operation when the load current is reduced
below the current limit point. This protects the
converter from both overload and short circuit
conditions. The current limit point exhibits a slightly
negative temperature coefficient to reduce the
possibility of thermal runaway.
An under-voltage lockout circuit prohibits the
converter from operating when the line voltage is too
low to maintain the output voltage. The converter will
not start until the line voltage rises to approximately
17 volts and will shut down when the input voltage
drops below 16 volts. The one volt of hysteresis
reduces the possibility of line noise interfering with
the converter’s start-up and shut down.
An external inhibit port is provided to control converter
operation. The converter’s operation is inhibited
when this pin is pulled low. It is intended to be driven
by an open collector logic device. The pin may be
left open for normal operation and has a nominal
open circuit voltage of 10.5V with respect to the input
return (pin 2).
Single output models feature remote sense to
automatically correct for voltage drops between the
converter output anf the load. The output voltage of
dual output models can be adjusted using a single
external resistor.
Design Methodology
The M3H-Series was developed using a proven
conservative design methodology which includes
selecting radiation tolerant and established reliability
components and fully derating to the requirements
of MIL-STD-975 and MIL-STD-1547. Heavy derating
of the power MOSFET gate and drain voltages
minimize the possibility of SEGR and SEB. A
magnetic feedback circuit is utilized instead of opto-
couplers to minimize temperature, radiation and
aging sensitivity. PSPICE was used extensively to
predict and optimize circuit performance for both
beginning and end-of-life. Thorough design
analyses include Radiation Susceptibility ( TREE ),
Stress, Thermal, and Reliability ( MTBF ).
2
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M3H-SERIES
Specifications
Absolute Maximum Ratings
Input voltage range
Output power
Lead temperature
Operating temperature
Storage temperature
-0.5Vdc to +60Vdc
Internally limited
Recommended Operating Conditions
Input voltage range
1
+18Vdc to +40Vdc
+18Vdc to +38Vdc
0 to Max. Rated
2
1
Input voltage range
+300°C for 10 seconds Output power
-55°C to +135°C
-55°C to +135°C
1
2
Operating temperature
Operating temperature
-55°C to +125°C
-55°C to +70°C
Electrical Performance Characteristics
Group A
Subgroup
Meets derating per MIL-STD-975
For operation at +125°C see table note 13
Limits
Min
18
Nom
28
3.30
5.00
5.20
12.00
15.00
±5.00
±12.00
±15.00
Max
40
3.33
5.05
5.23
12.12
15.15
±5.05
±12.12
±15.15
3.37
5.10
5.27
12.24
15.30
±5.10
±12.24
±15.30
30
40
9.10
8.00
7.70
3.34
2.67
6.40
2.67
2.14
0.5
1.0
V
Unit
V
Parameter
Input Voltage
Output Voltage ( Vout )
M3H2803R3S
M3H2805S
M3H2805R2S
M3H2812S
M3H2815S
M3H2805D
M3H2812D
M3H2815D
M3H2803R3S
M3H2805S
M3H2805R2S
M3H2812S
M3H2815S
M3H2805D
M3H2812D
M3H2815D
Output power ( P
OUT
)
M3H2803R3S
All Others
Output current ( I
OUT
)
M3H2803R3S
M3H2805S
M3H2805R2S
M3H2812S
M3H2815S
M3H2805D
M3H2812D
M3H2815D
Line regulation ( VR
LINE
)
Load regulation ( VR
LOAD
)
Cross regulation ( VR
CROSS
)
M3H2805D
M3H2812D
M3H2815D
Conditions
-55°C
≤
T
C
≤
+85°C
V
IN
= 28V DC ± 5%, C
L
= 0
unless otherwise specified
1
1
1
1
1
1
1
1
2,3
2,3
2,3
2,3
2,3
2,3
2,3
2,3
1,2,3
I
OUT
= 100% rated load
Note 4
3.27
4.95
5.17
11.88
14.85
±4.95
±11.88
±14.85
3.23
4.90
5.13
11.76
14.70
±4.90
±11.76
±14.70
0
0
0
0
0
0
0
0
0
0
-0.5
-1.0
I
OUT
= 100% rated load
Note 4
V
IN
= 18, 28, 40 Volts, Note 2
W
1,2,3
V
IN
= 18, 28, 40 Volts, Note 2
A
Either Output, Note 3
Either Output, Note 3
Either Output, Note 3
1,2,3
1,2,3
V
IN
= 18, 28, 40 Volts
I
OUT
= 0, 50%, 100% rated, Note 4
I
OUT
= 0, 50%, 100% rated, Note 4
V
IN
= 18, 28, 40 Volts
Duals only, Note 5
V
IN
= 18, 28, 40 Volts
%
%
1,2,3
-5.0
-3.0
-3.0
5.0
3.0
3.0
%
For Notes to Specifications, refer to page 5
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3
M3H-SERIES
Electrical Performance Characteristics
Group A
Subgrou
p
1,2,3
( continued )
Limits
Min
Nom
Max
35
50
50
70
80
80
80
80
Unit
Parameter
Output Ripple ( Vrip)
M3H2803R3S
M3H2805S
M3H2805R2S
M3H2812S
M3H2815S
M3H2805D
M3H2812D
M3H2815D
Input current, no load ( I
IN
)
M3H2803R3S
M3H2805S
125
M3H2805R2S
M3H2812S
M3H2815S
M3H2805D
M3H2812D
M3H2815D
Input current inhibited
Switching frequency ( F
S
)
Efficiency ( E
FF
)
M3H2803R3S
M3H2805S
M3H2805R2S
M3H2812S
M3H2815S
M3H2805D
M3H2812D
M3H2815D
Enable Input ( Inhibit Function )
open circuit voltage
drive current ( sink )
voltage range
Current Limit Point
Expressed as a percentage
of full rated load current
Power dissipation, load fault (P
D
)
M3H2815D
All others
Output response to
step load changes (V
TLD
)
Recovery time,
step load changes (T
TLD
)
Output response to
step line changes (V
TLN
)
Recovery time,
step line changes (T
TLN
)
Turn-on Response
Overshoot (V
OS
)
Turn-on Delay (T
DLY
)
Overshoot (V
OS
)
Turn-on Delay (T
DLY
)
Conditions
-55°C
≤
T
C
≤
+85°C
V
IN
= 28V DC ± 5%, C
L
= 0
unless otherwise specified
V
IN
= 18, 28, 40 Volts
I
OUT
= 100% rated load
Notes 4, 6
mV p-p
1,2,3
I
OUT
= 0, Pin 4 open
1,2,3
1,2,3
1,2,3
Pin 4 shorted to pin 2
450
I
OUT
= 100% rated load
Note 4
68
76
77
78
78
77
78
78
9.5
-0.5
500
73
80
80
81
82
80
81
82
60
70
70
70
70
70
100
100
8.0
550
mA
mA
KHz
%
1,2,3
Note 1
11.5
500
50
130
V
µA
V
%
1,2,3
V
out
= 90% of Nominal, Note 4
105
1,2,3
Short Circuit, Overload, Note 8
22
18
W
mV pk
µs
mV pk
µs
4,5,6
4,5,6
4,5,6
4,5,6
Half Load to/from Full Load, Notes 4,9
Half Load to/from Full Load, Note
4,9,10
18V to/from 40V
I
OUT
= 100% rated load, Notes 1,4,11
18V to/from 40V
I
OUT
= 100% rated load, Notes 1,4,10,11
No Load, Full Load for Dual
Notes 4,12
20 % Load, Full Load for Single
Notes 4,12
-300
300
200
-300
300
200
4,5,6
4,5,6
2.0
2.0
10
10
10
10
%
ms
%
ms
For Notes to Specifications, refer to page 5
4
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M3H-SERIES
Electrical Performance Characteristics
Group A
Parameter
Capacitive Load (CL)
M3H2803R3S
M3H2805S
M3H2005R2S
M3H2812S
M3H2815S
M3H2805D
M3H2812D
M3H2815D
Line Rejection
Isolation
Device Weight
MTBF
MIL-HDBK-217F2, SF, 35°C
1.5 x 10
6
( continued )
Limits
Min
Nom
Max
2200
1000
1000
180
120
500
90
60
40
100
125
50
Unit
Conditions
-55°C
≤
T
C
≤
+85°C
V
IN
= 28V DC
±
5%, C
L
=0
Unless otherwise specified
I
OUT
= 100% rated load
No effect on DC performance
Notes 1, 4, 7
Each output on duals
Subgroup
1
µF
1
1
I
OUT
= 100% rated load
DC to 50KHz, Notes 1, 4
Input to Output or Any Pin to Case
except pin 3, test @ 500VDC
dB
MΩ
g
Hr
Notes.
1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
11)
12)
13)
Electrical Performance Characteristics
Parameter is tested as part of design characterization or after design changes. Thereafter, parameter shall be guaranteed to the
limits specified.
Parameter verified during line and load regulation tests.
Output load current must be distributed such that at least 20% of the total load current is being provided by one of the outputs.
Load current split equally between outputs on dual output models.
Cross regulation is measured with 20% rated load on output under test while changing the load on the other output from 20% to 80%
of rated.
Guaranteed for a D.C. to 20MHz bandwidth. Tested using a 20KHz to 10MHz bandwidth using the circuit shown below.
Capacitive load may be any value from 0 to the maximum limit without compromising dc performance. A capacitive load in excess
of the maximum limit may interfere with the proper operation of the converter’s overload protection, causing erratic behavior during
turn-on.
Overload power dissipation is defined as the device power dissipation with the load set such that V
OUT
= 90% of nominal.
Load step transition time
≤
10
µ
s.
Recovery time is measured from the initiation of the transient to where V
OUT
has returned to within ±1% of
its steady state value.
Line step transition time
≤
100
µ
s.
Turn-on delay time from either a step application of input power or a logic low to a logic high transition on the inhibit pin (pin 4) to
the point where V
OUT
= 90% of nominal.
For operation at temperatures between +85°C and +125°C, derate the maximum output power linearly from 100% to 75%.
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5
