Document 499-1 Coupled Inductors–MSD1278 For SEPIC and other Applications The excellent coupling coefficient (k ≥ 0.94) makes the MSD1278 series of coupled inductors ideal for use in SEPIC applications. In SEPIC topologies, the required inductance for each winding in a coupled inductor is half the value needed for two separate inductors, allowing selection of a part with lower DCR and higher current handling. These inductors provide high inductance, 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, as a common mode choke or as a 1 : 1 transformer. 0.484 max 12,3 D1 + + L1 0.484 max 12,3 123 X C1 Dot indicates pin1 Parts manufactured prior to Sept. 2007 were marked with only the dash number. Dash number Internal code VIN L2 Q1 C2 + Load – VOUT – Typical SEPIC schematic Refer to Application Note, Document 639, “Selecting Coupled Inductors for SEPIC Applications” 0.317 max 8,05 Recommended Land Pattern 0.217 5,5 0.197 5,0 0.138 3,5 0.197 5,0 0.157 4,0 3 4 2 1 2 1 3 4 0.059 1,5 Dimensions are in inches mm 0.177 4,5 0.079 2,0 1 L1 3 2 L2 4 Designer’s Kit C400 contains 3 each of all values. 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 +85°C with Irms current, +85°C to +125°C with derated current Storage temperature Component: –40°C to +125°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 Specifications subject to change without notice. Please check our website for latest information. © Coilcraft, Inc. 2010 Document 499-1 Revised 10/08/08 Document 499-2 Coupled Inductors for SEPIC – MSD1278 Series SRF typ4 (MHz) Isat5 (A) Irms (A) both one windings6 winding7 Part number1 Inductance2 (µH) DCR max3 (Ohms) MSD1278-472ML_ MSD1278-562ML_ MSD1278-682ML_ MSD1278-822ML_ MSD1278-103ML_ 4.7 ±20% 5.6 ±20% 6.8 ±20% 8.2 ±20% 10 ±20% 0.038 0.046 0.048 0.050 0.058 32.0 25.0 24.0 18.0 16.5 14.9 13.4 13.1 10.8 10.5 3.16 2.87 2.81 2.76 2.56 4.47 4.06 3.98 3.90 3.62 MSD1278-123ML_ MSD1278-153ML_ MSD1278-183ML_ MSD1278-223ML_ 12 15 18 22 ±20% ±20% ±20% ±20% 0.062 0.072 0.080 0.096 14.5 11.8 10.5 9.0 9.6 9.1 8.0 6.8 2.48 2.30 2.18 1.99 3.50 3.25 3.08 2.81 MSD1278-273ML_ MSD1278-333ML_ MSD1278-393ML_ MSD1278-473ML_ MSD1278-563ML_ 27 33 39 47 56 ±20% ±20% ±20% ±20% ±20% 0.120 0.150 0.160 0.180 0.190 8.4 7.6 6.5 6.0 5.6 6.5 5.6 5.5 5.2 4.5 1.78 1.59 1.54 1.45 1.41 2.52 2.25 2.18 2.05 2.00 MSD1278-683ML_ MSD1278-823ML_ MSD1278-104ML_ MSD1278-124KL_ MSD1278-154KL_ 68 82 100 120 150 ±20% ±20% ±20% ±10% ±10% 0.210 0.280 0.300 0.410 0.460 5.0 4.1 3.6 3.2 3.0 4.1 3.8 3.4 3.2 2.8 1.35 1.16 1.13 0.96 0.91 1.90 1.65 1.59 1.36 1.29 MSD1278-184KL_ MSD1278-224KL_ MSD1278-274KL_ MSD1278-334KL_ MSD1278-394KL_ 180 220 270 330 390 ±10% ±10% ±10% ±10% ±10% 0.510 0.690 0.900 1.02 1.12 2.7 2.5 2.1 2.0 1.8 2.5 2.3 2.1 1.9 1.7 0.86 0.74 0.65 0.61 0.58 1.22 1.05 0.92 0.86 0.82 MSD1278-474KL_ MSD1278-564KL_ MSD1278-684KL_ MSD1278-824KL_ MSD1278-105KL_ 470 560 680 820 1000 ±10% ±10% ±10% ±10% ±10% 1.43 1.69 2.29 2.55 2.83 1.6 1.5 1.4 1.3 1.1 1.6 1.5 1.3 1.2 1.1 0.50 0.47 0.41 0.39 0.37 0.70 0.67 0.58 0.55 0.52 Temperature rise calculation based on specified Irms 1. When ordering, please specify termination and packaging code: MSD1278-105KLD 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. DC current, at which the inductance drops 30% (typ) from its value without current. It is the sum of the current flowing in both windings. 6. Equal current when applied to each winding simultaneously that causes a 40°C temperature rise from 25°C ambient. See temperature rise calculation. 7. Maximum current when applied to one winding that causes a 40°C temperature rise from 25°C ambient. See temperature rise calculation. 8. 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. Winding power loss = (IL12 + IL22 ) × DCR in Watts (W) 52.6°C Temperature rise (Δt) = Winding power loss × W 52.6°C Δt = (IL12 + IL22 ) × DCR × W Example 1. MSD1278-153ML (Equal current in each winding) Winding power loss = (2.3 2 + 2.3 2) × 0.072 = 0.761 W 52.6°C = 40°C Δt = 0.761 W × W Example 2. MSD1278-153ML (IL1 = 2.4 A, IL2 = 1.3 A) Winding power loss = (2.4 2 + 1.3 2) × 0.072 = 0.536 W Δt = 0.536 W × 52.6°C = 28.2°C W 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. Visit www.coilcraft.com/coupledloss. Specifications subject to change without notice. Please check our website for latest information. © Coilcraft, Inc. 2010 Document 499-2 Revised 10/08/08 Document 499-3 Coupled Inductors for SEPIC – MSD1278 Series Typical L vs Current Typical L vs Frequency 10000 10000 -105 -474 -104 100 -473 -103 10 -105 1000 Inductance (µH) Inductance (µH) 1000 -474 -104 100 -473 -103 10 -472 -472 1 1 0.1 10 1 100 0.01 Current (A) 0.1 1 10 Frequency (MHz) Current Derating 100 90 80 70 60 50 40 30 20 25°C Percent of rated current 120 110 Isat Irms 10 0 -40 -20 0 20 40 60 80 100 120 140 Ambient temperature (°C) Specifications subject to change without notice. Please check our website for latest information. © Coilcraft, Inc. 2010 Document 499-3 Revised 10/08/08