Document 922-1
Coupled Inductors – MSC1278
For SEPIC
Applications
The MSC1278 coupled inductors are designed with
high leakage inductance for use in SEPIC applications.
The loosely coupled windings (K
≈
0.8) improve SEPIC
efficiency by reducing circulating current and provide
twice the ripple current reduction of separate inductors.
These inductors offer high efficiency and excellent cur-
rent handling in a rugged, low cost part. They are well
suited for use as a VRM inductors in high-current DC-DC
converters and VRM/VRD controllers.
They can also be used as two single inductors connected
in series or parallel.
0.484
max
12,3
Dot indicates pin1
Dash number
Internal code
+
L1
V
IN
Q1
C1
D1
+
+
Load
V
OUT
0.484
max
12,3
123
X
L2
C2
–
Refer to Application Note, Document 639,
“Selecting Coupled Inductors for SEPIC Applications.”
Visit http://www.coilcraft.com/apps/sepic/selector_2.cfm
for the Coilcraft on-line SEPIC Inductor Selector tool.
–
Typical SEPIC schematic
0.317
max
8,05
Recommended
Land Pattern
0.197
5,0
0.138
3,5
0.157
4,0
2
3
0.217
5,5
0.197
5,0
3
2
4
1
0.177
4,5
4
1
0.059
1,5
0.079
2,0
1
2
L2
inches
Dimensions are in
mm
L1
3
1
:
1
4
Core material
Ferrite
Core and winding loss
Go to online calculator
Terminations
RoHS compliant matte tin over nickel over phos
bronze. Other terminations available at additional cost.
Ambient temperature
–40°C to +85°C with
Irms
current, +85°C to
+125°C with derated current
Storage temperature
Component: –40°C to +125°C.
Tape and reel 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
Tested with pure water or alcohol only. For other
solvents, see
Doc787_PCB_Washing.pdf.
Document 922-1
Revised 06/24/11
US
+1-847-639-6400 sales@coilcraft.com
UK
+44-1236-730595 sales@coilcraft-europe.com
Taiwan
+886-2-2264 3646 sales@coilcraft.com.tw
China
+86-21-6218 8074 sales@coilcraft.com.cn
Singapore
+ 65-6484 8412 sales@coilcraft.com.sg
© Coilcraft Inc. 2020
This product may not be used in medical or high
risk applications without prior Coilcraft approval.
Specification subject to change without notice.
Please check web site for latest information.
Document 922-2
Coupled Inductors for SEPIC – MSC1278 Series
Part
number
1
MSC1278-103ML_
MSC1278-223KL_
MSC1278-333KL_
MSC1278-473KL_
Inductance
(µH)
10 ±20%
22 ±10%
33 ±10%
47 ±10%
2
DCR
max
3
(Ohms)
0.058
0.096
0.15
0.18
SRF
typ
4
(MHz)
20
12
9.5
7.8
Coupling
Leakage
coefficient inductance
5
typ
typ (µH)
0.80
0.82
0.85
0.83
2.75
5.85
10.1
14.5
10%
drop
8.80
6.00
5.50
3.70
Isat
(A)
6
20%
30%
drop
drop
10.0
6.80
6.10
4.34
10.66
7.26
6.52
4.60
Irms
(A)
both
one
windings
7
winding
8
2.56
1.99
1.59
1.45
3.62
2.81
2.25
2.05
1. When ordering, please specify
termination
and
packaging
code:
MSC1278-473KLD
Termination: L
= RoHS compliant matte tin over nickel over phos
bronze
Special order:
T
= RoHS tin-silver-copper (95.5/4/0.5) or
S
= non-RoHS tin-lead (63/37).
Packaging: D
= 13″ machine-ready reel. EIA-481 embossed plastic
tape (500 parts per full reel). Quantities less than
full reel available: in tape (not machine ready) or
with leader and trailer ($25 charge).
B
= Less than full reel. In an effort to simplify our part
numbering system, Coilcraft is eliminating the need
for multiple packaging codes. When ordering, sim-
ply change the last letter of your part number from
B to D.
2. Inductance shown for each winding, measured at 100 kHz, 0.1 Vrms,
0 Adc on an Agilent/HP 4284A LCR meter or equivalent. When leads
are connected in parallel, inductance is the same value. When leads
are connected in series, inductance is four times the value.
3. DCR is for each winding. When leads are connected in parallel, DCR
is half the value. When leads are connected in series, DCR is twice the
value.
4. SRF measured using an Agilent/HP 4191A or equivalent. When leads
are connected in parallel, SRF is the same value.
5. Leakage inductance is for L1 and is measured with L2 shorted.
6. DC current, at which the inductance drops the specified amount from
its value without current. It is the sum of the current flowing in both
windings.
7. Equal current when applied to each winding simultaneously that
causes a 40°C temperature rise from 25°C ambient. See temperature
rise calculation.
8. Maximum current when applied to one winding that causes a 40°C
temperature rise from 25°C ambient. See temperature rise calculation.
9. Electrical specifications at 25°C.
Refer to Doc 639 “Selecting Coupled Inductors for SEPIC Applications.”
Refer to Doc 362 “Soldering Surface Mount Components” before soldering.
Coupled Inductor Core and Winding Loss Calculator
This web-based utility allows you to enter frequency, peak-to-peak
(ripple) current, and
Irms
current to predict temperature rise and overall
losses, including core loss.
Go to online calculator
.
Current Derating
110
100
90
Percent of rated
I
rms
80
70
60
50
40
30
20
10
0
-40
-20
0
Ambient temperature (°C)
20
25°C
40
60
80
100
120 140
L vs Current
100
47 µH
L vs Frequency
100
47 µH
33 µH
Inductance (µH)
22 µH
10
10 µH
Inductance (µH)
33 µH
22 µH
10 µH
10
1
0.1
1
1
Current (A)
10
100
0.1
1
Frequency (MHz)
10
100
US
+1-847-639-6400 sales@coilcraft.com
UK
+44-1236-730595 sales@coilcraft-europe.com
Taiwan
+886-2-2264 3646 sales@coilcraft.com.tw
China
+86-21-6218 8074 sales@coilcraft.com.cn
Singapore
+ 65-6484 8412 sales@coilcraft.com.sg
Document 922-2
Revised 06/24/11
© Coilcraft Inc. 2020
This product may not be used in medical or high
risk applications without prior Coilcraft approval.
Specification subject to change without notice.
Please check web site for latest information.
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