F
EATURES
•
•
•
•
•
•
•
•
•
•
–55° to +125°C operation
16 to 40 VDC input
Fully isolated
Optocoupler feedback
Fixed frequency, 550 kHz typical
(400 kHz typ. 60 V output model)
Topology – Flyback
50 V for up to 50 ms transient protection
Inhibit function
Indefinite short circuit protection
Up to 76% efficiency, 16 W/in
3
Size (max.):
Weight:
Screening:
DC/DC C
ONVERTERS
28 V
OLT
I
NPUT
MSA SERIES
5 WATT
MODELS
VDC O
UTPUT
SINGLE
5
5.2
12
15
60
DUAL
±5
±12
±15
1.075 x 1.075 x 0.270 inches (27.31 x 27.31 x 6.86 mm)
15 grams maximum.
Standard, ES, or 883 (Class H).
DESCRIPTION
The MSA Series™ of high frequency DC/DC converters offers a new
standard of performance for low power, military/aerospace grade
DC/DC converters. MSA parts provide up to 5 watts output power
over the full military temperature range with up to 76% efficiency.
Thick-film hybrid techniques provide military/aerospace reliability
levels and optimum miniaturization. The hermetically sealed case is
only 1.075 by 1.075 inches — with a height of only 0.270 inches.
Power density for the MSA Series parts is 16 watts per cubic inch.
The MSA Series’ small size, low height, and hermetically sealed
metal enclosures make them ideal for use in military, aerospace and
other high reliability applications. Units are available with standard,
screening, “ES”, and fully compliant SMD “883” screening. See
page 8 for screening options and descriptions.
W
IDE
V
OLTAGE
R
ANGE
The MSA 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. Please refer to the low line dropout graphs
(Figures 17 and 18) for details. A low voltage lockout feature keeps
the converter shutdown below approximately 13 VDC to ensure
smooth initialization.
I
MPROVED
D
YNAMIC
R
ESPONSE
The MSA feed-forward compensation system provides excellent
dynamic response and noise rejection. Audio rejection is typically 50
dB. The minimum to maximum step line transient response is typi-
cally less than 1%.
I
NHIBIT
F
UNCTION
MSA converters provide a TTL open collector-compatible inhibit
feature that can be used to disable internal switching and inhibit the
unit’s output. Inhibiting in this manner results in low standby current,
and no generation of switching noise.
The converter is inhibited when the 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 4 mA must be sunk from the inhibit pin.
C
ONVERTER
D
ESIGN
The MSA converters are switching regulators that use a flyback
converter design with a constant switching frequency of 550 kHz.
They are regulated, isolated units using a pulse width modulated
topology and built as high reliability thick-film hybrids. Isolation
between input and output circuits is provided with a transformer in
the forward power path and an optical link in the feedback control
loop. Excellent input line transient response and audio rejection is
achieved by an advanced feed-forward compensation technique.
Negative output regulation is maintained by tightly coupled
magnetics. Up to 4 watts, 80% of the total output power, is available
from either output, provided that the opposite output is simultane-
ously carrying 20% of the total power. Each output must carry a
minimum of 20% of the total output power in order to maintain spec-
ified regulation on the negative output. Predictable current limit is
accomplished by direct monitoring of the output load current, which
results in a constant current output above the overload point.
Internal input and output filters eliminate the need for external
capacitors.
U
NDERVOLTAGE
L
OCKOUT AND
T
RANSIENT
P
ROTECTION
Undervoltage lockout helps keep system current levels low during
initialization or re-start operations. They can withstand short term
transients of up to 50 volts without damage.
1
MSA SERIES
5 WATT
ABSOLUTE MAXIMUM RATINGS
Input Voltage
• 16 to 40 V
Output Power
• 5 watts
Lead Soldering Temperature (10 sec per lead)
• 300°C
Storage Temperature Range (Case)
• –65°C to +135°C
DC/DC C
ONVERTERS
INHIBIT
Inhibit TTL Open Collector
• Logic low (output disabled)
Logic low voltage
≤0.8
V max
Inhibit pin current 4 mA max
• Referenced to input common
• Logic high (output enabled)
Open collector
TYPICAL CHARACTERISTICS
Output Voltage Temperature Coefficient
• 100 ppm/°C typical
Input to Output Capacitance
• 50 pF typical
Isolation
• 100 megohm minimum at 500 V
Audio Rejection
• 50 dB typical
Conversion Frequency
• 550 kHz typical (400 kHz 60 V model)
450 kHz min, 600 kHz max
350 kHz min, 450 kHz max 60 V model
Inhibit Pin Voltage (unit enabled)
• 9 to 11 V
RECOMMENDED OPERATING CONDITIONS
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 (Tc)
• Linearly from 100% at 125°C to 0% at 135°C
Electrical Characteristics: 25°C Tc, 28 VDC Vin, 100% load, unless otherwise specified.
SINGLE OUTPUT MODELS
PARAMETER
CONDITIONS
OUTPUT VOLTAGE
Tc = –55°C TO +125°C
OUTPUT CURRENT
Tc = –55°C TO +125°C V
IN
= 16 TO 40 VDC
OUTPUT POWER
OUTPUT RIPPLE
VOLTAGE
LINE REGULATION
LOAD REGULATION
INPUT VOLTAGE
NO LOAD TO FULL
INPUT CURRENT
Tc = –55°C TO +125°C
INPUT RIPPLE
CURRENT
EFFICIENCY
LOAD FAULT
3, 4
SHORT CIRCUIT
STEP LOAD
RESPONSE
4, 5
STEP LINE
RESPONSE
4, 5
V
IN
= 16 TO 40 VDC
Tc = –55°C TO +125°C
10 kHz - 2 MHz
V
IN
= 16 TO 40 VDC
Tc = –55°C TO +125°C
NO LOAD TO FULL
Tc = –55°C TO +125°C
Tc = –55°C TO +125°C
CONTINUOUS
TRANSIENT 50 ms
NO LOAD
FULL LOAD
INHIBITED
10 kHz - 10 MHz
Tc = –55°C TO +125°C
POWER DISSIPATION
RECOVERY
50% - 100% - 50%
TRANSIENT
RECOVERY
TRANSIENT
16 TO 40 V
IN
40 TO 16 V
IN
RECOVERY
16 TO 40 V
IN
START-UP
40 TO 16 V
IN
DELAY
OVERSHOOT
—
—
—
—
16
0
—
—
—
—
—
66
—
—
—
—
—
—
—
—
—
—
—
125
10
10
28
—
27
250
3
25
30
71
1.5
12.5
100
100
50
50
100
200
10
0
5
350
50
2
50
40
50
40
—
5
100
150
—
2.0
25
250
250
150
150
250
500
25
50
—
—
—
—
16
0
—
—
—
—
—
66
—
—
—
—
—
—
—
—
—
—
—
110
10
10
28
—
28
250
3
25
30
71
1.5
1.5
100
100
50
50
100
200
10
0
5
335
50
50
40
50
40
—
5
100
150
—
2.0
25
250
250
150
150
250
500
25
50
—
—
—
—
16
0
—
—
—
—
—
70
—
—
—
—
—
—
—
—
—
—
—
50
10
10
28
—
29
235
3
25
30
76
1.2
1
150
200
80
100
250
250
3
0
5
200
50
50
40
50
42
—
5
100
150
—
1.9
10
375
500
200
250
625
625
10
120
—
—
—
—
16
0
—
—
—
—
—
71
—
—
—
—
—
—
—
—
—
—
—
50
10
10
28
—
31
235
3
25
30
76
1.2
1
200
200
50
50
250
250
3
0
5
170
50
50
40
50
44
—
5
100
150
—
1.8
10
500
500
125
125
625
625
10
150
—
—
—
—
16
0
—
—
—
—
—
70
—
—
—
—
—
—
—
—
—
—
—
—
—
—
28
—
—
72
3
—
—
75
—
—
—
—
—
—
—
—
—
—
1.2
300
300
300
40
50
30
—
5
90
—
—
—
—
—
—
—
—
—
—
—
—
W
mV p-p
mV
mV
VDC
V
mA
MSA2805S
MSA285R2S
MSA2812S
MSA2815S
MIN TYP MAX MIN TYP MAX MIN TYP MAX MIN TYP MAX
4.95 5.00 5.05 5.15 5.20 5.25 11.88 12.00 12.12 14.85 15.00 15.15
0
—
1000
0
—
962
0
—
417
0
—
333
MSA2860S
1
MIN TYP MAX
59.1 60.00 60.9
0
—
20
UNITS
VDC
mA
mA p-p
%
W
ms
mV pk
µs
mV pk
µs
ms
mV pk
Notes
1. MSA2860S specifications are at 25°Tc only, contact your Interpoint
representative for more information on over temperature specs.
2. Line regulation for /ES and non /ES 2805S models at 16 to 17 V
IN
and 110
°C to 125°C (case) is 5% (max).
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
V
OUT
is within 1% of V
OUT
at final value.
5. Transition time >10µs.
2
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