PD-94559M
M3G-SERIES
HYBRID-HIGH RELIABILITY
RADIATION HARDENED
DC-DC CONVERTER
Description
The M3G-Series of DC-DC converters are radiation
hardened, high reliability converters designed for
extended operation in hostile environments. Their small
size and low weight make them ideal for applications
such as geostationary earth orbit satellites and deep
space probes. They exhibit a high tolerance to total
ionizing dose, single event effects and environmental
stresses such as temperature extremes, mechanical
shock, and vibration.
The converters incorporate a fixed frequency single
ended forward topology with magnetic feedback and
an internal EMI filter that utilizes multilayer ceramic
capacitors that are subjected to extensive lot screening
for optimum reliability. These converters are capable of
meeting the conducted emissions and conducted
susceptibility requirements of MIL-STD-461C without
additional components. External inhibit and synchronization
input and output allow these converters to be easily
incorporated into larger power systems. They are
enclosed in a hermetic 3" x 2" x 0.475" package
constructed of an Aluminum-Silicon-Carbide (AlSiC)
base and an Alloy 48 ring frame and they weigh less
than 110 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 DLA
Land and Maritime qualified processes. For available
screening options, refer to device screening table in the
data sheet.
Non-flight versions of the M3G-Series converters are
available for system development purposes. Variations
in electrical specifications and screening to meet custom
requirements can be accommodated.
50V Input, Triple Output
M3G
Features
n
Total Dose > 200 krad(Si),
typically usable to > 300 krad(Si)
n
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n
n
n
n
n
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SEE Hardened up to 82 MeV
.
cm
2
/mg
Low Weight, < 110 grams
Low Input & Output Noise
Magnetically Coupled Feedback
38V to 60V DC Input Range
Up to 40W Output Power
Triple Output Models Include
+5V and
±
12V or
±
15V
Main Output Isolated from Dual Outputs
High Efficiency - to 80%
-55°C to +125°C Operating Temperature Range
100M
Ω
@ 500VDC Isolation
Under-Voltage Lockout
Synchronization Input and Output
Short Circuit and Overload Protection
Output Over Voltage Limiter
External Inhibit
5,000,000 Hour MTBF
Applications
n
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Geostationary Earth Orbit Satellites (GEO)
Deep Space Satellites / Probes
Strategic Weapons and Communication
Systems
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1
09/12/12
M3G-SERIES
(50V Input, Triple Output)
Circuit Description
The M3G-Series converters utilize a single-ended
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 with duty factor limiting provides high
line rejection and protection against output over
voltage in the event of an internal control loop failure.
This mechanism limits the maximum output voltage
to approximately 20% over the nominal regardless of
the line voltage.
An internal EMI filter reduces the conducted emissions
to less than 5mA rms on the input power leads. A two
stage output filter reduces the typical output ripple to
less than 20mV peak-to-peak.
The main (+5 volt) output is regulated by the control
loop and typically exhibits better than 1% regulation.
The auxiliary (±12 volt or ±15 volt) outputs are
maintained through tight coupling in the power
transformer and main output filter inductor and
typically exhibit better than 5% regulation. The main
output and auxiliary outputs are isolated from each
other.
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
36 volts and will shut down when the input voltage
drops below 34 volts. This two volts 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 nominal threshold relative to the input
return (pin 2) is 1.4V. If 2.0 volts or greater are applied
to the Inhibit pin (pin 3) then the converter will
operate normally. A voltage of 0.8V or less will cause
the converter to shut-down. The pin may be left
open for normal operation and has a nominal open
circuit voltage of 4.0V.
Synchronization input and output allow multiple
converters to operate at a common switching fre-
quency. Converters can be synchronized to one
another or to an externally provided clock. This can
be used to eliminate beat frequency noise or to avoid
creating noise at certain frequencies for sensitive
systems.
Design Methodology
The M3G-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 except for the
CDR type ceramic capacitors, a capacitor with 50V
rating is used for in-circuit voltage stress of less than
10V. Careful sizing of decoupling capacitors and
current limiting resistors minimizes the possibility of
photo-current burn-out. Heavy derating of the
radiation hardened power MOSFET virtually
eliminates the possibility of SEGR and SEB. A
magnetic feedback circuit is utilized instead of opto-
couplers to minimize temperature, radiation and
aging sensitivity. PSPICE and RadSPICE were used
extensively to predict and optimize circuit
performance for both beginning and end-of-life.
Thorough design analyses include Radiation
Susceptibility (TREE ), Worst Case, Stress, Thermal,
Failure Modes and Effects (FMEA) and Reliability
(MTBF).
2
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M3G-SERIES
(50V Input, Triple Output)
Specifications
Absolute Maximum Ratings
Input voltage range
Output power
Lead temperature
Operating temperature
Storage temperature
-0.5Vdc to +80Vdc
Internally limited
300°C for 10 seconds
-55°C to +135°C
-55°C to +135°C
1
Recommended Operating Conditions
Input voltage range
Output power
Operating case temperature
1
+38Vdc to +60Vdc
0 to Max. Rated
-55°C to +125°C
Electrical Performance Characteristics
Parameter
Group A
Subgroup
For operation at +125°C see table note 15
Conditions
-55°C
≤
T
C
≤
+85°C
V
IN
= 28V DC ± 5%, C
L
= 0
unless otherwise specified
Note 2
Limits
Min
38
Nom
50
Max
60
Unit
Input Voltage
Output Voltage ( Vout )
(main)
M3G500512T (aux.)
M3G500515T (aux.)
(main)
M3G500512T (aux.)
M3G500515T (aux.)
Output power ( P
OUT
)
Output current ( I
OUT
)
1, 2, 3
V
1
I
OUT
= 100% rated load, Note 5
4.98
±11.50
±14.60
4.93
±11.30
±14.40
0
5.00
±11.80
±14.90
5.02
±12.10
±15.20
V
5.07
±12.30
±15.40
40
W
2, 3
I
OUT
= 100% rated load, Note 5
1, 2, 3
V
IN
= 38, 50, 60 Volts, Note 2
(main)
M3G500512T (aux.)
M3G500515T (aux.)
1, 2, 3
V
IN
= 38, 50, 60 Volts, Notes 2,3,4,5
400
±83
±67
4000
±833
±667
mA
Line regulation ( VR
LINE
)
(main)
M3G500512T (aux.)
M3G500515T (aux.)
Load regulation ( VR
LOAD
)
(main)
M3G500512T (aux.)
M3G500515T (aux.)
Cross regulation ( VR
CROSS
)
1, 2, 3
I
OUT
= 10%, 50%, 100% rated
V
IN
= 38, 50, 60 Volts
Notes 5,13
-50
-400
-500
50
400
500
mV
1, 2, 3
I
OUT
= 10%, 50%, 100% rated
V
IN
= 38, 50, 60 Volts
Note 5
-10
-120
-150
10
120
150
mV
(main)
M3G500512T (aux.)
M3G500515T (aux.)
1, 2, 3
V
IN
= 38, 50, 60 Volts
I
OUT
= 2.5A to 1A and 2.5 to 4A on main
output and ±half rated on aux. outputs
-3.5
-3.0
3.5
3.0
%
For Notes to Electrical Performance Characterstics Table, refer to page 5
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3
M3G-SERIES
(50V Input, Triple Output)
Electrical Performance Characteristics
Parameter
Group A
Subgroup
1, 2, 3
( continued )
Limits
Min
Nom
Max
80
5.0
mA
Unit
Conditions
-55°C
≤
T
C
≤
+85°C
V
IN
= 28V DC ± 5%, C
L
= 0
unless otherwise specified
I
OUT
= 0, Pin 3 open
Pin 3 shorted to pin 2
Input current ( I
IN
)
Output ripple ( V
RIP
)
(main)
M3G500512T (aux.)
M3G500515T (aux.)
1, 2, 3
V
IN
= 38, 50, 60 Volts
I
OUT
= 100% rated load, Notes 5, 6
25
30
30
50
60
75
mV p-p
Switching frequency ( F
S
)
Efficiency ( E
ff
)
Inhibit Input
1, 2, 3
1, 2, 3
Sync. Input (Pin 4) open
I
OUT
= 100% rated load
Note 5
Note 1
450
75
500
79
550
KHz
%
open circuit voltage
drive current ( sink )
voltage range
3.0
-0.5
5.0
100
50
600
10
0.5
80
V
µA
V
KHz
V
V
V/
µ
s
%
Synchronization Input
frequency range
pulse high level
pulse low level
pulse transition time
pulse duty cycle
Current Limit Point
Expressed as a percentage
of full rated output power
Power dissipation, load fault (P
D
)
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
)
Ext. Clock on Sync. Input (Pin 4)
Note 1
450
4.0
-0.5
40
20
1, 2, 3
V
out
= 90% of Nominal, Note 5
135
%
1, 2, 3
4, 5, 6
Short Circuit, Overload, Note 8
Half Load to/from Full Load, Notes 5,9
-300
20
300
W
mV pk
4, 5, 6
Half Load to/from Full Load, Note 5,9,10
18V to/from 50V
I
OUT
= 100% rated load, Notes 1,5,11
18V to/from 50V
I
OUT
= 100% rated load, Notes 1,5,10,11
-300
100
300
100
µs
mV pk
µ
s
For Notes to Electrical Performance Characterstics Table, refer to page 5
4
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M3G-SERIES
(50V Input, Triple Output)
Electrical Performance Characteristics
Parameter
Group A
Subgroup
( continued )
Limits
Min
Nom
Max
Unit
Conditions
-55°C
≤
T
C
≤
+85°C
V
IN
= 28V DC ± 5%, C
L
= 0
unless otherwise specified
No Load, Full Load
Notes 5,12
Turn-on Response
Overshoot (V
OS
)
(main)
M3G500512T (aux.)
M3G500515T (aux.)
Turn-on Delay (T
DLY
)
Capacitive Load (CL)
(main)
(Each aux. output)
Line Rejection
Isolation
4, 5, 6
500
750
1000
1.0
5.0
1000
200
40
100
60
mV
ms
µF
dB
MΩ
I
OUT
= 100% rated load, No effect on DC
performance, Notes 1, 5, 7
I
OUT
= 100% rated load
DC to 50KHz, Notes 1, 5
1
Input to Output or Any Pin to Case
except pin 10, test @ 500VDC
Device Weight
MTBF
MIL-HDBK-217F2, SF, 35ºC
5 x 10
6
110
g
Hrs
Notes: Electrical Performance Characteristics
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
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.
Although operation with no load is permissible, light loading on the main (+5 volt) output may cause the output voltage of the
auxiliary outputs(±12 volt or ±15 volt) to drop out of regulation. It is therefore recommended that at least 200 mA or 20 percent of
the total output power, whichever is greater, be taken from the main (+5 volt) output.
Although operation with no load is permissible, heavy loading on the main (+5 volt) output may cause the output voltage of the
auxiliary outputs(±12 volt or ±15 volt) to rise out of regulation. It is therefore recommended that at least 50 mA or 20 percent of
the total output power, whichever is greater, be taken from the auxiliary (±12 volt or ±15 volt) outputs.
Unless otherwise specified, “Rated” load is 20W on the main (+5 volt) output and 10 watts each on the auxiliary (±12 volt or
±15 volt) outputs. Load currents of up to 5A and ±1A on the main and auxiliary outputs respectively are acceptable as long as
the total output power does not to exceed 40 watts.
Guaranteed for a D.C. to 20MHz bandwidth. Tested using a 20KHz to 10MHz bandwidth.
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
³
10
µs.
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
³
100
µs.
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(pin3 to
the point where V
OUT
= 90% of nominal.
Load is varied for output under test while the remaining outputs are loaded at 50% of rated. Regulation relative to output voltage
at 50% rated load.
Although operation at temperatures between +85°C and +125°C is guaranteed, no parametric limits are
specified.
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