PD-94584K
HYBRID-HIGH RELIABILITY
RADIATION HARDENED
LOW POWER
DC-DC CONVERTER
Description
The S-Series of DC-DC converters are low power
radiation hardened, high reliability devices designed
for hostile radiation environments such as those
encountered by geostationary earth orbit satellites, deep
space probes and communication systems. Features
include small size, high efficiency, low weight and a
high tolerance to total ionizing dose, single event effects,
and environmental stresses such as temperature
extremes, mechanical shock, and vibration. Extensive
documentation including Radiation Susceptibility,
Thermal Analysis, Stress Analysis and MTBF are
available.
The converters incorporate a fixed frequency single
ended forward topology with magnetic feedback and
an internal EMI filter utilizing large multilayer ceramic
capacitors processed per MIL-PRF-49470 for improved
reliability. All models include an external inhibit port .
They are encased in a hermetic 1.71” x 1.31” x 0.45”
steel package and weigh less than 50 grams. The
package utilizes rugged ceramic feed-through copper
core pins and is hermetically 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 S-Series converters are
available for system development purposes. Variations
inelectrical specifications and screening to meet custom
requirements can be accommodated.
S-SERIES
28V Input, Single/Dual Outpu
t
S
Features
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Total Dose >100K Rad(Si)
SEE Hardened to LET up to 82 MeV
.
cm
2
/mg
Low Weight < 50 grams
Magnetically Coupled Feedback
18V to 40V DC Input Range
Up to 10W Output Power
Single and Dual Output Models Include
3.3, 5, 7,12,15,
±
5,
±
12 and
±
15V
High Efficiency - to 82%
-55°C to +125°C Operating Temperature Range
100M
Ω
@ 500VDC Isolation
Under-Voltage Protection
Short Circuit and Overload Protection
Output Over Voltage Limiter
External Inhibit
Standard Microcircuit Drawings Available
Applications
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Geostationary or Low Earth Orbit Satellites
Launch Vehicles
Communication Systems
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1
04/17/13
S-SERIES
(28V Input, Single/Dual Output)
Circuit Description
The S-Series converters utilize a single-ended
forward topology with resonant reset. The nominal
switching frequency is 525KHz. 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.
Output power is limited under any load fault condition
to approximately 135% for singles and 145% for
duals 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. There are no
latching elements included in the load fault protection
circuits to eliminate the possibility of falsely triggering
the protection circuits during single event radiation
exposure.
An under-voltage protection circuit prohibits the
converter from operating when the line voltage is
too low for safe operation. The converter will not
start until the line voltage rises to approximately 12V.
An external enable port is provided to control
converter operation. This input is intended for
operation with an open collector transistor drive or
a relay closure to the input return. The pin may be
left open for normal operation and has a nominal
open circuit voltage of 10.5V.
Design Methodology
The S-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 of capacitors, a capacitor
with 50V rating is used for in-circuit voltage stress of
less than10V. 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
was 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
and Reliability (MTBF).
2
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S-SERIES
(28V Input, Single/Dual Output)
Specifications
Absolute Maximum Ratings
Input voltage range
Output power
Lead temperature
Operating temperature
Storage temperature
-0.5Vdc to +60Vdc
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 temperature
Operating temperature
1
+18Vdc to +40Vdc
0 to Max. Rated
-55°C to +125°C
-55°C to +70°C
Meets derating per MIL-STD-975
Limits
Unit
Min
18
Nom
28
3.30
5.00
7.00
12.00
15.00
±5.00
±12.00
±15.00
Max
40
3.33
5.05
7.07
12.12
15.15
±5.05
±12.12
±15.15
3.370
5.100
7.105
12.240
15.300
±5.100
±12.240
±15.300
V
V
Electrical Performance Characteristics
Parameter
Group A
Subgroup
Conditions
-55°C
≤
T
C
≤
+85°C
V
IN
= 28V DC ± 5%, C
L
= 0
unless otherwise specified
Input Voltage
Output Voltage ( V
OUT
)
S2803R3S
S2805S
S2807S
S2812S
S2815S
S2805D
S2812D
S2815D
S2803R3S
S2805S
S2807S
S2812S
S2815S
S2805D
S2812D
S2815D
Output power ( P
OUT
)
All models
Output current ( I
OUT
)
S2803R3S
S2805S
S2807S
S2812S
S2815S
S2805D
S2812D
S2815D
Line regulation ( VR
LINE
)
S28XXS
S28XXD
Load regulation ( VR
LOAD
)
S28XXS
S28XXD
Cross regulation ( VR
CROSS
)
S2805D
S2812D
S2815D
1
1
1
1
1
1
1
1
2,3
2,3
2,3
2,3
2,3
2,3
2,3
2,3
I
OUT
= 100% rated load
Note 4
3.27
4.95
6.93
11.88
14.85
±4.95
±11.88
±14.85
3.230
4.900
6.895
11.760
14.700
±4.900
±11.760
±14.700
I
OUT
= 100% rated load
Note 4
1,2,3
1,2,3
V
IN
= 18, 28, 40 Volts, Note 2
V
IN
= 18, 28, 40 Volts, Note 2
0
0
0
0
0
0
0.16
0.06
0.05
-0.5
-0.5
10
3.03
2.00
1.43
0.83
0.67
1.60
0.66
0.54
0.5
0.5
W
A
Either Output, Note 3
Either Output, Note 3
Either Output, Note 3
1,2,3
V
IN
= 18, 28, 40 Volts
I
OUT
= 0, 50%, 100% rated
I
OUT
= 10%, 50%, 100% rated, Note 4
1,2,3
V
IN
= 18, 28, 40 Volts
I
OUT
= 0, 50%, 100% rated
I
OUT
= 10%, 50%, 100% rated, Note 4
1,2,3
Duals only, Note 5
V
IN
= 18, 28, 40 Volts
%
-1.0
-1.0
1.0
1.0
%
-5.0
-3.0
-3.0
5.0
3.0
3.0
%
For Notes to Electrical Performance Characteristic Table, refer to page 6
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3
S-SERIES
(28V Input, Single/Dual Output)
Electrical Performance Characteristics
Parameter
Group A
Subgroup
( continued )
Limits
Unit
Min
2.0
2.0
2.0
2.0
2.0
5.0
3.0
3.0
Nom
Max
2.0
2.0
2.0
2.0
2.0
5.0
3.0
3.0
60
70
70
70
70
70
70
70
5.0
475
525
575
50
50
45
50
60
80
80
80
68
75
76
78
77
76
76
76
9.5
-0.5
73
80
81
81
82
80
81
82
11.5
500
50
Conditions
-55°C
≤
T
C
≤
+85°C
V
IN
= 28V DC ± 5%, C
L
= 0
unless otherwise specified
V
IN
= 18, 28, 40 Volts
Single Output: I
OUT
= 0% ,50%,100%
of rated current Note 14
Dual Output: I
OUT
= 10% ,50%,100%
of rated current Notes 4, 14
Total Regulation
S2803R3S
S2805S
S2807S
S2812S
S2815S
S2805D
S2812D
S2815D
Input current ( I
IN
)
S2803R3S
S2805S
S2807S
S2812S
S2815S
S2805D
S2812D
S2815D
1,2,3
%
1,2,3
I
OUT
= 0, Pin 4 open
mA
Pin 4 shorted to pin 2
Switching frequency ( F
S
)
Output ripple ( V
RIP
)
S2803R3S
S2805S
S2807S
S2812S
S2815S
S2805D
S2812D
S2815D
Efficiency ( E
FF
)
S2803R3S
S2805S
S2807S
S2812S
S2815S
S2805D
S2812D
S2815D
Enable Input ( Inhibit Function )
Open circuit voltage
Drive current ( sink )
Voltage range
Current Limit Point
Expressed as a percentage
of full rated load current
S2803R3S
S2805S
S2807S
S2812S
S2815S
S2805D
S2812D
S2815D
1,2,3
mA
KHz
1,2,3
V
IN
= 18, 28, 40 Volts
I
OUT
= 100% rated load
Notes 4, 6
mV p-p
1,2,3
I
OUT
= 100% rated load
Note 4
%
1,2,3
Note 1
V
µA
V
1,2,3
V
OUT
= 90% of Nominal, Note 4, 13
105
105
110
105
110
105
105
105
140
140
144
145
146
150
160
167
%
For Notes to Electrical Performance Characteristic Table, refer to page 6
4
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S-SERIES
(28V Input, Single/Dual Output)
Electrical Performance Characteristics
Parameter
Group A
Subgroup
( continued )
Limits
Unit
Min
Nom
Max
9.0
-300
300
W
mV pk
Conditions
-55°C
≤
T
C
≤
+85°C
V
IN
= 28V DC ± 5%, C
L
= 0
unless otherwise specified
Short Circuit, Overload, Note 8
Half Load to/ from Full Load, Notes 4,9
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
)
Turn-on Response
Overshoot ( V
OS
)
S2803R3S
S2805S
S2807S
S2812S
S2815S
S2805D
S2812D
S2815D
Turn-on Delay ( T
DLY
)
Capacitive Load ( C
L
)
S2803R3S
S2805S
S2807S
S2812S
S2815S
S2805D
S2812D
S2815D
Line Rejection
Isolation
Device Weight
MTBF
1,2,3
4,5,6
4,5,6
Half Load to/from Full Load, Notes
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
-300
200
µs
4,5,6
4,5,6
300
200
mV pk
µs
4,5,6
10% Load, Full Load
Notes 4,12
1.5
1
I
OUT
= 100% rated load
No effect on DC performance
Notes 1, 4, 7
500
600
750
1400
1650
600
1400
1500
10
2200
1000
750
180
120
500
90
60
50
mV
ms
µF
Each output on duals
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
MIL-HDBK-217F2, SF, 35°C
100
dB
MΩ
50
g
Hours
1.5 x 10
6
For Notes to Electrical Performance Characteristic Table, refer to page 6
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