Document 922-1 For SEPIC Coupled Inductors MSC1278 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 D1 max 12,3 ++ L1 C1 Dotindicates pin1 + 123 V V Q1 L2 C2 Load IN OUT 0.484 Dashnumber max 12,3 X Internalcode Typical SEPIC schematic Refer to Application Note, Document 639, 0.317 max Selecting Coupled Inductors for SEPIC Applications. 8,05 Recommended Visit Document 922-2 Coupled Inductors for SEPIC MSC1278 Series 6 Isat (A) Irms (A) DCR SRF Coupling Leakage 2 3 4 5 Part Inductance max typ coefficient inductance 10% 20% 30% both one 1 7 8 number (H) (Ohms) (MHz) typ typ (H) drop drop drop windings winding MSC1278-103ML 10 20% 0.058 20 0.80 2.75 8.80 10.0 10.66 2.56 3.62 MSC1278-223KL 22 10% 0.096 12 0.82 5.85 6.00 6.80 7.26 1.99 2.81 MSC1278-333KL 33 10% 0.15 9.5 0.85 10.1 5.50 6.10 6.52 1.59 2.25 MSC1278-473KL 47 10% 0.18 7.8 0.83 14.5 3.70 4.34 4.60 1.45 2.05 1. When ordering, please specify termination and packaging code: Coupled Inductor Core and Winding Loss Calculator This web-based utility allows you to enter frequency, peak-to-peak MSC1278-473KLD (ripple) current, and Irms current to predict temperature rise and overall Termination: L = RoHS compliant matte tin over nickel over phos losses, including core loss. Go to online calculator. 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. Current Derating 4. SRF measured using an Agilent/HP 4191A or equivalent. When leads are connected in parallel, SRF is the same value. 110 5. Leakage inductance is for L1 and is measured with L2 shorted. 100 6. DC current, at which the inductance drops the specified amount from 90 its value without current. It is the sum of the current flowing in both windings. 80 7. Equal current when applied to each winding simultaneously that causes a 40C temperature rise from 25C ambient. See temperature 70 rise calculation. 60 8. Maximum current when applied to one winding that causes a 40C temperature rise from 25C ambient. See temperature rise calculation. 50 9. Electrical specifications at 25C. 40 Refer to Doc 639 Selecting Coupled Inductors for SEPIC Applications. Refer to Doc 362 Soldering Surface Mount Components before soldering. 30 20 10 0 -40 -20 020406080 100 120 140 Ambient temperature (C) L vs Current L vs Frequency 100 100 47 H 47 H 33 H 33 H 22 H 22 H 10 H 10 10 10 H 1 1 0.1 1 10 100 0.1 1 10 100 Current (A) Frequency (MHz) Document 922-2 Revised 06/24/11 US +1-847-639-6400 sales coilcraft.com UK +44-1236-730595 sales coilcraft-europe.com Coilcraft Inc. 2013 This product may not be used in medical or high Taiwan +886-2-2264 3646 sales coilcraft.com.tw risk applications without prior Coilcraft approval. China +86-21-6218 8074 sales coilcraft.com.cn Specification subject to change without notice. Singapore + 65-6484 8412 sales coilcraft.com.sg Please check web site for latest information. Inductance (H) Inductance (H) Percent of rated Irms 25C