MSC1278

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 current 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
0.484
max
12,3
123
X
D1
+
L1
Dot indicates pin1
VIN
Dash number
Internal code
+
C1
L2
Q1
C2
+
Load
–
VOUT
–
Typical SEPIC schematic
0.317
max
8,05
Recommended
Land Pattern
0.217
5,5
0.197
5,0
0.138
3,5
0.197
5,0
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.
3
2
0.157
4,0
4
2
1
1
3
4
0.059
1,5
0.079
2,0
1
Dimensions are in
inches
mm
0.177
4,5
2
L1
3
L2
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.
US +1-847-639-6400 [email protected]
UK +44-1236-730595 [email protected]
Taiwan +886-2-2264 3646 [email protected]
China +86-21-6218 8074 [email protected]
Singapore + 65-6484 8412 [email protected]
Document 922-1 Revised 06/24/11
© Coilcraft Inc. 2013
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
DCR SRF CouplingLeakage
typ4coefficient
inductance5
Part Inductance2 max3 number1
(µH)
(Ohms)
(MHz)
typ
typ (µH)
Isat (A)6
Irms (A)
10%
20%30% both
one
drop
drop drop windings7 winding8
MSC1278-103ML_
MSC1278-223KL_
MSC1278-333KL_
MSC1278-473KL_
8.80
6.00
5.50
3.70
10±20%
22±10%
33±10%
47±10%
0.058
0.096
0.15
0.18
20
12
9.5
7.8
0.80
0.82
0.85
0.83
2.75
5.85
10.1
14.5
10.0 10.66
6.80 7.26
6.10 6.52
4.34 4.60
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:
Coupled Inductor Core and Winding Loss Calculator
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).
B = Less than full reel. In tape, but not machine ready.
To have a leader and trailer added ($25 charge),
use code letter D instead.
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.
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
80
70
60
50
40
25°C
Percent of rated Irms
90
30
20
10
0
-40
L vs Current
-20
0
40
60
80
100
120 140
L vs Frequency
100
100
47 µH
33 µH
47 µH
33 µH
Inductance (µH)
Inductance (µH)
20
Ambient temperature (°C)
22 µH
10
10 µH
1
22 µH
10 µH
10
1
0.1
1
Current (A)
10
100
0.1
US +1-847-639-6400 [email protected]
UK +44-1236-730595 [email protected]
Taiwan +886-2-2264 3646 [email protected]
China +86-21-6218 8074 [email protected]
Singapore + 65-6484 8412 [email protected]
1
10
Frequency (MHz)
100
Document 922-2 Revised 06/24/11
© Coilcraft Inc. 2013
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.