Crane Aerospace & Electronics Power Solutions
SMTR Single, Dꢀꢁl ꢁnd Triple DC/DC Converters
28 VOꢂT INPuT – 30 WaTT – PENDINꢃ REVISION F REꢂEaSE
Wi D e vo l t a g e ra n g e
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-704D emergency power conditions is possible
with derated power.
in h i b i t Fu n c t i o n
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 an active
lowꢀ(≤0.8V)ꢀisꢀappliedꢀtoꢀtheꢀinhibitꢀpin.ꢀTheꢀunitꢀisꢀenabledꢀwhenꢀ
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
VDC. In the inhibit mode, a maximum of 8 mA must be sunk from
the inhibit pin.
im p r o v e D Dy n a m i c re S p o n S e
The SMTR Series feed-forward compensation system provides
excellent dynamic response and noise rejection. Audio rejection
is typically 50 dB (for Triple output models). The min. to max.
step line transient response is typically less than 4%.
TRIM aND REMOTE SENSE (aVaIꢂabꢂE ON SINꢃꢂE OuTPuT MODEꢂS ONꢂy)
SMTR SINGLE OUTPUT CONVERTER
SMTR SINGLE OUTPUT CONVERTER
1
4
1
4
OUTPUT
COMMON
OUTPUT
COMMON
+V
+V
IN
IN
1
SENSE
2
2
SENSE
RETURN
RETURN
3
6
3
6
R
R
L
L
SENSE
SENSE
1
R
T
INPUT
COMMON
POSITIVE
OUTPUT
INPUT
COMMON
POSITIVE
OUTPUT
10
5
10
5
EXTERNAL TRIM CONNECTION
REMOTE SENSE CONNECTION
2 Make connections at load.
1
Make connections at converter.
1, 2, 3
2,
3
Fi g u r e 1: tr i m CO n n e C t i O n
Fi g u r e 2: re m O t e Se n S e
ꢀotes for Remote Sense and Trim
Trim Formulas
1.ꢀWhenꢀtrimmingꢀoutputꢀvoltageꢀand/orꢀremoteꢀsensing,ꢀtheꢀ
total output voltage increase must be less than 0.6 volts at the
converters pins to maintain specified performance.
2. If neither voltage trim nor remote sense will be used, connect pin 3
to pin 4 and pin 5 to pin 6 or the output voltage will increase by 1.2
volts.
Vout = desired output voltage; Rt = trim resistor
3.3V: Rt = 1300 Vout – 4304
*
1.2475
5V: Rt = 1300 Vout – 6512
*
1.2475
12V: Rt = 1300 Vout – 15631
3. CAUTIOꢀ: The converter will be permanently damaged if the posi-
tive remote sense (pin 6) is shorted to ground. Damage may also
result if the output common or positive output is disconnected from
the load with the remote sense leads connected to the load.
*
1.2475
15V: Rt = 1300 Vout – 19498
*
1.2475
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Rev F - 20090324 - Pending Revision F Release
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