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 Inductance2 max3 typ4 Part number1 (µH) (Ohms) (MHz) MSC1278-103ML_ MSC1278-223KL_ MSC1278-333KL_ MSC1278-473KL_ 10 ±20% 22 ±10% 33 ±10% 47 ±10% 0.058 0.096 0.15 0.18 20 12 9.5 7.8 Coupling Leakage coefficient inductance5 typ typ (µH) 0.80 0.82 0.85 0.83 10% drop 2.75 5.85 10.1 14.5 Isat (A)6 Irms (A) 20% 30% both one drop drop windings7 winding8 8.80 6.00 5.50 3.70 10.0 6.80 6.10 4.34 10.66 7.26 6.52 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 10 100 Document 922-2 Revised 06/24/11 Frequency (MHz) © 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.