International Rrectifier PD - 94519A User Manual

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PD - 94519A

L-SERIES

ADVANCED ANALOG
HIGH RELIABILITY RADIATION
TOLERANT DC/DC CONVERTERS

Description

The L-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 G-Series of DC/DC con­verters is recommended. Features include 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 and GSFC
PPL-21 Appendix B. 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 1.5" x 2.3" x 0.425" steel package
and weigh less than 85 grams. The package utilizes
rugged ceramic feed-through copper core pins and is
sealed using parallel seam welding.

Full environmental screening includes temperature cy­cling, constant acceleration, fine and gross leak, and
burn-in.

Non-flight versions of the L-Series converters are avail­able for system development purposes. Variations in
electrical specifications and screening to meet custom
requirements can be accommodated.

+ 28V Input, Single/Dual Output

Features

n Total Dose > 25K Rad(Si)

n SEE > 37 MeV.cm

n Internal EMI filter; Converter Capable of

meeting MIL-STD-461C CE03 and CS01

n Low Weight, < 85 grams
n Magnetically Coupled Feedback
n 16V to 50V DC Input Range
n Up to 25W Output Power
n Single and Dual Output Models Include

3.3, 5, 12, 15,

n High Efficiency - to 82%
n -55°C to +125°C Operating Temperature

Range

n 100M
n Under-Voltage Lockout
n Short Circuit and Overload Protection
n Output Over Voltage Limiter
n Adjustable Output Voltage
n External Inhibit
n 1,500,000 Hour MTBF

Ω @ 500VDC Isolation

2

/mg

±5, ±12 and ±15V

Applications

n Low Earth Orbit Satellites (LEO)
n Launch Vehicles

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08/20/02

L-SERIES

Circuit Description

The L-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 allows the converter to meet the
conducted emissions requirements of MIL-STD-461C
on the input power leads. A single-stage output filter
reduces the typical output ripple to less than 50mV
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 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).

The output voltage of all models can be adjusted
using a single external resistor.

Design Methodology

The L-Series was developed using a proven con­servative design methodology which includes se­lecting radiation tolerance 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, Ther mal,
and Reliability ( MTBF ).

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L-SERIES

Absolute Maximum Ratings Recommended Operating Conditions

Input voltage range - -0.5Vdc to +60Vdc Input voltage range - 16Vdc to +60Vdc
Output power - Internally limited Input voltage range

1

- 16Vdc to +38Vdc
Lead temperature - +300°C for 10 seconds Output power - 0 to Max. Rated
Operating temperature - -55°C to +135°C Operating temperature
Storage temperature - -55°C to +135°C Operating temperature

1

Meets derating per MIL-STD-975

2

For operation at +125°C see table note 13

2

- -55°C to +125°C

1

- -55°C to +70°C

Electrical Performance Characteristics

Input Voltage 18 28 50 V

Output Voltage ( Vout )

Output power ( P

Output current ( I

Line regulation ( VR

Load regulation ( VR

Cross regulation ( VR

Parameter

M3L2803R3S

M3L2805S
M3L2812S

M3L2815S
M3L2805D
M3L2812D
M3L2815D

M3L2803R3S

M3L2805S
M3L2812S
M3L2815S
M3L2805D
M3L2812D
M3L2815D

)

M3L2803R3S

M3L2803R3S

OUT

All Others

OUT

M3L2805S
M3L2812S
M3L2815S
M3L2805D
M3L2812D
M3L2815D

M3L2805D
M3L2812D
M3L2815D

)

LINE

LOAD

CROSS

) 1,2,3 VIN = 16, 28, 50 Volts

Group A

Subgroup

) 1,2,3 I

)

1
1
1
1
1
1
1

2,3
2,3
2,3
2,3
2,3
2,3
2,3

1,2,3

1,2,3

1,2,3

Conditions

-55°C ≤ T

VIN = 28V DC ± 5%, CL = 0

unless otherwise specified

I

OUT

I

OUT

VIN = 16, 28, 50 Volts, Note 2

VIN = 16, 28, 50 Volts, Note 2

Either Output, Note 3
Either Output, Note 3
Either Output, Note 3

I

= 0, 50%, 100% rated, Note 4

OUT

= 0, 50%, 100% rated, Note 4

OUT

VIN = 16, 28, 50 Volts

VIN = 16, 28, 50 Volts

Duals only, Note 5

≤ +85°C

C

= 100% rated load

Note 4

= 100% rated load

Note 4

±11.88
±14.85

±11.76
±14.70

Min

3.27

4.95

11.88

14.85
±4.95

3.23

4.90

11.76

14.70
±4.90

0
0

0
0
0
0
0
0
0

-0.5

-1.0

-5.0

-3.0

-3.0

Limits

±12.00
±15.00

Nom

3.30

5.00

12.00

15.00
±5.00

12.12

15.15

±5.05
±12.12
±15.15

12.24

15.30

±5.10
±12.24
±15.30

Max

3.33

5.05

3.37

5.10

20
25

6.06

5.00

2.08

1.67

4.00

1.67

1.33

0.5 %

1.0 %

5.0

3.0

3.0

Unit

V
V
V
V
V
V
V

V
V
V
V
V
V
V

W
W

A
A
A
A
A
A
A

%
%
%

For Notes to Specifications, refer to page 5

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L-SERIES

Electrical Performance Characteristics ( continued )

Parameter

Input current, no load ( IIN )

M3L2803R3S

M3L2805S

Group A

Subgroup

1,2,3

Conditions

-55°C ≤ T

V

= 28V DC ± 5%, CL = 0

IN

unless otherwise specified

I

OUT

≤ +85°C

C

= 0, Pin 4 open

M3L2812S
M3L2815S
M3L2805D
M3L2812D
M3L2815D

Input current inhibited 1,2,3 Pin 4 shorted to pin 2

Output ripple ( V

M3L2803R3S

M3L2805S
M3L2812S

)

RIP

1,2,3

V

= 16, 28, 50 Volts

IN

= 100% rated load

I

OUT

Notes 4, 6
M3L2815S
M3L2805D
M3L2812D
M3L2815D

Switching frequency ( FS ) 1,2,3 Sync. Input (Pin 4) open 425 500 575 KHz
Efficiency ( EFF )

M3L2803R3S

M3L2805S

1,2,3

I

= 100% rated load

OUT

Note 4
M3L2812S
M3L2815S
M3L2805D
M3L2812D
M3L2815D

Enable Input ( Inhibit Function )

open circuit voltage

1,2,3

Note 1 9.5

drive current ( sink )

voltage range

Current Limit Point
Expressed as a percentage

1,2,3 V

= 90% of Nominal, Note 4 105

out

of full rated load current

Power dissipation, load fault (PD) 1,2,3 Short Circuit, Overload, Note 8

Output response to
step load changes (V

Recovery time,
step load changes (T

Output response to
step line changes (V

Recovery Time,
step line changes (T

Turn-on Response

Overshoot (V

Turn-on Delay (T

TLN

TLN

TLD

TLD

)

)

)

)

)

OS

)

DLY

4,5,6 Half Load to/from Full Load, Notes 4,9 -300

4,5,6 Half Load to/from Full Load, Note

4,9,10

4,5,6 16V to/from 50V

I

= 100% rated load, Notes 1,4,11

OUT

4,5,6 16V to/from 50V

I

= 100% rated load, Notes

OUT

4,5,6

1,4,10,11

No Load, Full Load

Notes 4,12

Min

68
75
75
75
75
75
75

-0.5

-300

Limits

Nom

75
79
80
81
79
79
80

2

Max

60
70
70
70

70
100
100

8 mA

35

50

70

80

80

80

80

11.5
500

50

130 %

14 W

300 mV pk

200

300 mV pk

200

500

10

Unit

mV p-p
mV p-p
mV p-p
mV p-p
mV p-p
mV p-p
mV p-p

mA
mA
mA
mA
mA
mA
mA

%
%
%
%
%
%
%

V

µ

V

µ

µ

mV
mS

A

S

S

For Notes to Specifications, refer to page 5

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