© Coilcraft, Inc. 2010
Specifications subject to change without notice.
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Document 704-1
Document 704-1
Revised 08/31/09
The MSD1278T series of coupled inductors was de-
signed for high temperature applications – up to 125°C.
The excellent coupling coefficient (k
≥ 0.94) makes it
ideal for use in SEPIC applications. In SEPIC topolo-
gies, the required inductance for each winding in a
coupled inductor is half the value needed for two sepa-
rate inductors, allowing selection of a part with lower
DCR and higher current handling.
These inductors provide high inductance, high effi-
ciency and excellent current handling in a rugged, low
cost part. They are well suited for use as VRM induc-
tors in high-current DC-DC and VRM/VRD controllers.
They can also be used as two single inductors con-
nected in series or parallel, as a common mode choke
or as a 1 : 1 transformer.
Dimensions are in
inches
mm
123
X
Recommended
Land Pattern
0.197
5,0
0.059
1,5
0.197
5,0
0.138
3,5
0.484
12,3
max
0.484
12,3
max
Dash number
Dot indicates pin1
Internal code
1
4
2
3
0.217
5,5
0.177
4,5
0.157
4,0
0.079
2,0
1
4
2
3
0.308 ±0.010
7,8 ±0,25
3
1
2
4
L1
L2
Core material Ferrite
Terminations RoHS compliant matte tin over nickel over phos
bronze. Other terminations available at additional cost.
Weight: 3.7 – 4.4 g
Ambient temperature –40°C to +125°C with
Irms current, +125°C
to +165°C with derated current
Storage temperature Component: –40°C to +165°C.
Packaging: –40°C to +80°C
Winding to winding isolation 500 Vrms
Resistance to soldering heat Max three 40 second reflows at
+260°C, parts cooled to room temperature between cycles
Moisture Sensitivity Level (MSL) 1 (unlimited floor life at <30°C /
85% relative humidity)
Failures in Time (FIT) / Mean Time Between Failures (MTBF)
38 per billion hours / 26,315,789 hours, calculated per Telcordia SR-332
Packaging 500/13
″ reel; Plastic tape: 24 mm wide, 0.4 mm thick,
16 mm pocket spacing, 8.1 mm pocket depth
PCB washing Only pure water or alcohol recommended
L1
L2
Q1
C1
C2
+
++
––
D1
VOUT
VIN
Load
Typical SEPIC schematic
Refer to Application Note, Document 639,
“Selecting Coupled Inductors for SEPIC Applications”
Coupled Inductors –MSD1278T Forhightemperature
SEPIC applications
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