F
EATURES
•
•
•
•
•
•
•
•
•
•
•
–55° to +125°C operation
16 to 40 VDC input
Fully isolated
Magnetic feedback
Fixed frequency 600 kHz typical
Topology – Single Ended Forward
50 V for up to 50 ms transient protection
Inhibit and synchronization functions
Indefinite short circuit protection
Up to 25 watts output power
Up to 73% efficiency
PRELIMINARY
DC/DC C
ONVERTERS
28 V
OLT
I
NPUT
SMTR TRIPLE SERIES
25 WATT
MODELS
VDC O
UTPUT
+5 & ±12
+5 & ±15
Size (max): Non-flanged: 1.950 x 1.350 x 0.405 inches (49.53 x 34.29 x 10.29 mm)
Flanged:
2.720 x 1.350 x 0.405 inches (69.09 x 34.29 x 10.29 mm)
See cases “F maximum dimensions,” “F1”, “J maximum dimensions,”
and “J1” for dimensions.
Weight:
Triple non-flanged 58 grams max., flanged 62 grams max.
Screening: Space Prototype, Class H, or Class K
Radiation hardness levels O or R
See “QA Screening: Class H and K, QML” for more information.
Available configurations: OO, HO, HR, KR
DESCRIPTION
The SMTR Triple Series™ of DC/DC converters offers up to 25
watts of output power from a triple output configuration. They
operate over the full military temperature range with up to 73% effi-
ciency. SMTR Triple converters are packaged in hermetically sealed
metal cases, making them ideal for use in military, aerospace and
other high reliability applications.
S
YNCHRONIZATION
Synchronizing the converter with the system clock allows the
designer to confine switching noise to clock transitions, minimizing
interference and reducing the need for filtering. In sync mode, the
converter will run at any frequency between 500 kHz and 675 kHz.
The sync control operates with a quasi-TTL signal at any duty cycle
between 40% and 60%. The sync pin must be connected to input
common pin when not in use.
C
ONVERTER
D
ESIGN
The SMTR converters are constant frequency, pulse-width mod-
ulated switching regulators which use a quasi-square wave, single
ended, forward converter design. Tight load regulation is maintained
via wide bandwidth magnetic feedback. The SMTR Triple Series
DC/DC converter’s design includes individual regulators on the
auxiliary outputs which provide for no cross regulation error when a
minimum 500 mA load is maintained on the main (+5) output.
Indefinite short circuit protection and overload protection are
provided by a constant current-limit feature. This protective system
senses current in the converter’s secondary stage and limits it to
approximately 115% of the maximum rated output current.
SMTR converters have internal filtering capacitors that help reduce
the need for external components in normal operation. For systems
that require compliance with MIL-STD-461C’s CE03 standard,
Interpoint offers filter/transient suppression modules which will
result in compliance. Contact your Interpoint representative for
further details.
W
IDE
V
OLTAGE
R
ANGE
SMTR 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.
I
MPROVED
D
YNAMIC
R
ESPONSE
The SMTR Triple Series feed-forward compensation system
provides excellent dynamic response and noise rejection. Audio
rejection is typically 50 dB. The minimum to maximum step line tran-
sient response is typically less than 4%.
I
NHIBIT
F
UNCTION
SMTR converters provide an inhibit terminal that can be used to
disable internal switching, resulting in no output and very low
quiescent input current. The converter is inhibited when a 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 8 mA must be sunk
from the inhibit pin.
SMTR TRIPLE SERIES
25 WATT
ABSOLUTE MAXIMUM RATINGS
Input Voltage
• 16 to 40 VDC
Output Power
• 25 to 25 watts depending on model
Lead Soldering Temperature (10 sec per pin)
• 300°C
Storage Temperature Range (Case)
• –65°C to +135°C
DC/DC C
ONVERTERS
SYNC AND INHIBIT
Sync (500 to 675 kHz)
• Duty cycle 40% min, 60% max
• Logic low 0.8 V max
• Logic high 4.5 V min, 5 V max
• Referenced to input common
• If not used, connect to input common
Inhibit TTL Open Collector
• Logic low (output disabled)
Voltage
≤0.8
V
Inhibit pin current 8.0 mA max
• Referenced to input common
• Logic high (output enabled)
Open collector
Preliminary
TYPICAL CHARACTERISTICS
Output Voltage Temperature Coefficient
• 100 ppm/°C typical single and dual outputs
• 200 ppm/°C main, 300 ppm/°C aux
triple output
Input to Output Capacitance
• 50 pF typ (100 pF typ triple outputs)
Current Limit
• 115% of full load typical
Isolation
• 100 megohm minimum at 500 V
Audio Rejection
• 40 dB typ (50 dB typ triple output)l
Conversion Frequency
• Free run 550 min, 600 typ, 650 max kHz
• External sync 500 to 675 kHz
Inhibit Pin Voltage (unit enabled)
• 9 to 11 V
RECOMMENDED OPERATING CONDITIONS
Input Voltage Range
• 16 to 40 VDC continuous
• 50 V for 50 msec transient
Case Operating Temperature (Tc)
• –55°C to +125°C full power
• –55°C to +135°C absolute
Derating Output Power/Current
• Linearly from 100% at 125°C to 0% at 135°C
PIN OUT
Squared corner and dot on top
of package indicate pin one.
Pin
1
2
3
4
5
6
7
8
9
10
Designation
Positive Input
Main (+5) Output
Output Common
Neg. Aux. Output
Pos. Aux. Output
Case Ground
Case Ground
Inhibit
Sync
Input Common
1
2
3
4
5
BOTTOM VIEW
SMTR TRIPLE
FLANGED AND NON-FLANGED
10
9
8
7
6
Dotted line outlines flanged package option.
See cases “F maximum dimensions,” “F1”,
“J maximum dimensions,” and “J1” for dimensions.
F
IGURE
1: P
IN
O
UT
SMTR T
RIPLE
MODEL NUMBERING KEY
SMTR
Base Model
Input Voltage
Output Voltage
(Main and aux. Vout for triple models)
Number of Outputs
(T = triple)
Case Option
("F" indicates flanged option, non-flanged
case has no designator in this position)
Screening
(OO-prototype, HO, HR, KR)
28 512 T
F / KR
Preliminary
DC/DC C
ONVERTERS
SMTR28512T
CONDITION
MAIN
+ AUXILIARY
– AUXILIARY
MIN
4.95
11.82
11.82
0.5
—
—
—
—
—
—
MAIN
± AUXILIARY
—
—
—
—
—
—
16
—
—
—
—
71
POWER DISSIPATION
SHORT CIRCUIT
ALL OUTPUTS SHORTED TOTAL
RECOVERY EACH OUTPUT
MAIN
± AUXILIARY
MAIN
± AUXILIARY
MAIN
± AUXILIARY
MAIN
± AUXILIARY
—
—
—
—
—
—
—
—
—
—
—
—
1.4
150
500
0.05
3
150
100
1.4
0
0
14
2.0
250
750
0.10
5
250
250
2.0
250
500
—
—
—
—
—
—
—
—
—
—
—
TYP
5.0
12.0
12.0
—
416
416
—
5
5
—
—
—
10
25
10
30
28
—
—
3.0
20
73
MAX
5.05
12.18
12.18
3.0
625
625
15
7.5
7.5
25
115
80
20
60
20
75
40
50
50
8
40
—
MIN
4.95
14.77
14.77
0.5
—
—
—
—
—
—
—
—
—
—
—
—
16
—
—
—
—
71
SMTR TRIPLE SERIES
25 WATT
SMTR28515T
TYP
5.0
15.0
15.0
—
333
333
—
5
5
—
—
—
10
30
10
30
28
—
—
3.0
20
73
MAX
5.05
15.23
15.23
3.0
500
500
15
7.5
7.5
25
115
80
20
75
50
75
40
50
50
8
40
—
mV p-p
mV
mV
VDC
mA
mA
mA p-p
%
W
A
mA
VDC
UNITS
Electrical Characteristics: 25°C Tc, 28 VDC Vin, 100% load, free run, unless otherwise specified.
TRIPLE OUTPUT MODELS
PARAMETER
OUTPUT VOLTAGE
OUTPUT CURRENT
1
V
IN
= 16 TO 40
OUTPUT POWER
1
V
IN
= 16 TO 40
MAIN
+ AUXILIARY
– AUXILIARY
MAIN
+ AUXILIARY
– AUXILIARY
TOTAL
OUTPUT RIPPLE
VOLTAGE
LINE REGULATION
V
IN
= 16 TO 40
LOAD REGULATION
2, 3
INPUT VOLTAGE
10 kHz to 2 MHz
MAIN
±AUXILIARY
MAIN
± AUXILIARY
CONTINUOUS
TRANSIENT 50 ms
INPUT CURRENT
INPUT RIPPLE CURRENT
EFFICIENCY
LOAD FAULT
4
NO LOAD
INHIBITED
10 kHz TO 10 MHz
—
1.4
150
500
0.05
2
150
100
1.4
0
0
14
2.0
250
750
0.10
5
250
250
2.0
250
500
W
ms
mV
ms
mV
ms
mV
STEP LOAD RESPONSE
TRANSIENT
5
RECOVERY
6
STEP LINE RESPONSE
V
IN
= 16 TO 40
START-UP
TRANSIENT
DELAY
OVERSHOOT
Notes
1. The sum of the two aux outputs is not to exceed 10 watts. The maximum
load per aux output is 7.5 watts.
2. To maintain regulation when operating the ±Aux at full load, a minimum load
of 500 mA is required on the main.
3. Measured on each output one at a time with the other outputs at full load.
4. Indefinite short circuit protection not guaranteed above 125°C (case).
5. Response of each output as all outputs are simultaneously transitioned.
Main: 50% - 100% - 50% of main full load
Auxiliaries: 25% - 50% - 25% each, of total auxiliary full load
6. Recovery time is measured from application of the transient to point at
which Vout is within 1% of regulation.
SMTR TRIPLE SERIES
25 WATT
80
16V
75
DC/DC C
ONVERTERS
80
16V
10
75
20
0
Preliminary
Typical Performance Curves: 25°C Tc, 28 VDC Vin, 100% load, free run, unless otherwise specified.
ATTENUATION (dB)
EFFICIENCY (%)
40V
70
28V
65
EFFICIENCY (%)
30
40
50
60
70
80
40V
70
28V
65
60
60
90
100
0.1
5
10
15
20
25
30
1
10
100
55
5
10
15
20
25
30
55
FREQUENCY (kHz)
OUTPUT POWER (WATTS)
OUTPUT POWER (WATTS)
SMTR SERIES AUDIO REJECTION
SMTR28512T EFFICIENCY
SMTR28515T EFFICIENCY
F
IGURE
2
F
IGURE
3
F
IGURE
4
20V/div
100mV/div
20V/div
1ms/div
50% to 100%
VIN
+5 VOUT
+5 V
50% to 100%
50
µs/div
VIN
100mV/div
+AUX
–AUX
–AUX
2V/div
+AUX
200mV/div
+5 VOUT
50µs/div
16V TO 40V
SMTR28515T STEP LINE RESPONSE
50%
100%
500
µs/div
SMTR28515T STEP LOAD RESPONSE
SMTR28515T, MAIN (+5)
TURN-ON INTO FULL LOAD
F
IGURE
5
F
IGURE
6
F
IGURE
7
16.0
16.0
INPUT VOLTAGE (VOLTS)
20V/div
INPUT VOLTAGE (VOLTS)
5
10
15
20
25
30
15.5
15.5
VIN
15.0
15.0
±15
VOUT
14.5
14.5
5V/div
14.0
14.0
13.5
13.5
500µs/div
5
10
15
20
25
30
SMTR28515T, AUX. (±15)
TURN-ON INTO FULL LOAD
OUTPUT POWER (WATTS)
1% DROP
SMTR28512T
LOW LINE DROPOUT VS. LOAD
OUTPUT POWER (WATTS)
1% DROP
SMTR28515T
LOW LINE DROPOUT VS. LOAD
F
IGURE
8
F
IGURE
9
F
IGURE
10
SMTR Triple Preliminary (format) September 8, 2005
All technical information is believed to be accurate, but no responsibility is
assumed for errors or omissions. Interpoint reserves the right to make changes in
products or specifications without notice. SMTR Series is a trademark of
Interpoint. Copyright © 2003-2005 Interpoint Corp. All rights reserved.
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