Document 704-1 Coupled Inductors – MSD1278T For high temperature SEPIC applications The MSD1278T series of coupled inductors was designed for high temperature applications – up to 125°C. The excellent coupling coefficient (k ≥ 0.94) makes it 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 VRM inductors in high-current DC-DC 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 VIN Dash number Internal code L2 Q1 C2 + Load – VOUT – Typical SEPIC schematic Refer to Application Note, Document 639, “Selecting Coupled Inductors for SEPIC Applications” 0.308 ±0.010 7,8 ±0,25 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 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 +125°C with Irms current, +125°C to +165°C with derated current Storage temperature Component: –40°C to +165°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 704-1 Revised 08/31/09 Document 704-2 High Temperature Coupled Inductors for SEPIC – MSD1278T Part number1 MSD1278T-472ML_ MSD1278T-562ML_ MSD1278T-682ML_ MSD1278T-822ML_ MSD1278T-103ML_ Inductance2 (µH) 4.7 ±20% 5.6 ±20% 6.8 ±20% 8.2 ±20% 10 ±20% DCR max3 (Ohms) 0.040 0.046 0.048 0.055 0.058 SRF typ4 (MHz) 33.0 30.0 23.0 20.0 17.0 10% drop 13.90 13.38 12.10 10.30 8.80 Isat (A)5 20% drop 15.20 14.86 13.56 11.52 10.00 30% drop 16.36 15.74 14.20 12.20 10.66 Irms (A) both one windings6 winding7 3.16 4.47 2.87 4.06 2.81 3.98 2.76 3.90 2.56 3.62 MSD1278T-123ML_ MSD1278T-153ML_ MSD1278T-183ML_ MSD1278T-223ML_ MSD1278T-273ML_ 12 15 18 22 27 ±20% ±20% ±20% ±20% ±20% 0.062 0.072 0.080 0.096 0.120 15.0 13.0 12.0 11.0 10.0 8.20 7.40 6.50 6.00 5.80 9.18 8.36 7.38 6.80 6.56 9.74 9.03 7.86 7.26 7.02 2.48 2.30 2.18 1.99 1.78 3.50 3.25 3.08 2.81 2.52 MSD1278T-333ML_ MSD1278T-393ML_ MSD1278T-473ML_ MSD1278T-563ML_ MSD1278T-683ML_ 33 39 47 56 68 ±20% ±20% ±20% ±20% ±20% 0.150 0.161 0.180 0.190 0.210 9.5 8.5 7.5 7.0 6.5 5.50 4.70 3.70 3.60 3.50 6.10 5.26 4.34 4.18 4.04 6.52 5.60 4.60 4.50 4.32 1.59 1.54 1.45 1.41 1.35 2.25 2.18 2.05 2.00 1.90 MSD1278T-823ML_ MSD1278T-104ML_ MSD1278T-124KL_ MSD1278T-154KL_ MSD1278T-184KL_ 82 100 120 150 180 ±20% ±20% ±10% ±10% ±10% 0.280 0.300 0.410 0.460 0.510 5.0 4.5 4.3 4.1 4.0 3.30 2.80 2.60 2.20 2.10 3.72 3.24 2.94 2.54 2.42 4.02 3.46 3.16 2.70 2.58 1.16 1.13 0.96 0.91 0.86 1.65 1.59 1.36 1.29 1.22 MSD1278T-224KL_ MSD1278T-274KL_ MSD1278T-334KL_ MSD1278T-394KL_ MSD1278T-474KL_ 220 270 330 390 470 ±10% ±10% ±10% ±10% ±10% 0.690 0.900 1.02 1.12 1.53 3.4 3.1 2.9 2.7 2.2 1.90 1.70 1.50 1.40 1.30 2.16 1.94 1.70 1.60 1.50 2.28 2.10 1.84 1.70 1.60 0.74 0.65 0.61 0.58 0.50 1.05 0.92 0.86 0.82 0.70 MSD1278T-564KL_ MSD1278T-684KL_ MSD1278T-824KL_ MSD1278T-105KL_ 560 680 820 1000 ±10% ±10% ±10% ±10% 1.69 2.29 2.55 2.87 2.0 1.7 1.4 1.3 1.20 1.00 0.900 0.850 1.34 1.08 1.04 0.948 1.46 1.22 1.18 1.05 0.47 0.41 0.39 0.37 0.67 0.58 0.55 0.52 1. When ordering, please specify termination and packaging code: MSD1278T-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 the specified amount 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. Temperature rise calculation based on specified Irms 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. MSD1278T-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. MSD1278T-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 704-2 Revised 08/31/09 Document 704-3 High Temperature Coupled Inductors for SEPIC – MSD1278T Typical L vs Current Typical L vs Frequency 10000 10000 1000 µH 470 µH 100 µH 100 1000 µH 1000 Inductance (µH) Inductance (µH) 1000 47 µH 10 µH 10 470 µH 100 µH 100 47 µH 10 µH 10 4.7 µH 1 4.7 µH 1 0.1 10 1 100 0.01 Current (A) 0.1 1 10 Frequency (MHz) Current Derating 120 100 90 80 70 60 50 40 25°C Percent of rated Current 110 30 20 Isat Irms 10 0 -40 -20 0 20 40 60 80 100 120 140 160 180 Ambient temperature (°C) Specifications subject to change without notice. Please check our website for latest information. © Coilcraft, Inc. 2010 Document 704-3 Revised 08/31/09