SD3814-1R2-R COOPER | Alldatasheet
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Introduction/Basic Operation In switching regulator applications the inductor is used as an energy storage device. When the semiconductor switch is on the current in the inductor ramps up and energy is stored. When the switch turns off energy is released into the load. The amount of energy stored is calculated by the formula EEnneerrggyy == ½½LL..II²² (Joules), where: L is the inductance in Henrys I is the peak value of inductor current The amount by which the current changes during a switching cycle is known as the ripple current. Ripple current is defined as VVll == LL..ddii//ddtt:: Vl is the voltage across the inductor di is the ripple current dt is the duration for which the voltage is applied Inductor current is made up of AC and DC components (Figure 1). The AC component is high frequency and will flow through the output capacitor because it has a low HF impedance. A ripple voltage is produced due to the capacitor ‘equivalent series resistance’ (ESR) that will appear at the output of the switching regulator. This ripple voltage needs to be sufficiently low as not to effect the operation of the circuit the regulator is supplying, normally in the order of 10-500mVpk-pk. Selecting the correct ripple current impacts the size of the inductor and output capacitor. The capacitor needs to have a sufficiently high ripple current rating or it will overheat and dry out. To achieve a good compromise between inductor and capacitor size a ripple current value of 10-30% of maximum inductor current should be chosen. The current in the inductor will be continuous for output currents greater that 5-15% of full load. The following parameters need to be defined or calculated to select an inductor: Maximum input voltage Output voltage Switching frequency Maximum ripple current Duty cycle 1 2 I load I inductor dI V out ESR Figure 1: Buck Inductor Inductor Selection for Switching Regulators SD3814
Note: For full product information and a listing of all available inductor values, see http://www.cooperbussmann.com/datasheets/elx, Data Sheet number SD38 Series. NNoottee: For full product information and a listing of all available inductor values, see http://www.cooperbussmann.com/datasheets/elx, Data Sheet number SDH3812 Series. SDH3812 Dimensions - mm Recommended Pad Layout SchematicTop View Side View Bottom View Pin #1 indicator Marking 1.25 Typ. 1.2 Max. 0.415 Min. 0.90 Max. no plating 4.8 Max. 2.5 2 plcs 1.0 2 plcs 5.0 Top View Side View Bottom View Recommended Pad Layout Schematic 1.4 Max 1.25 ±0.12 2.5 2p l c s 1.0 2p l c s 4.0 typ 5.0 4.0 Max4.0 Max Pin #1 indicator Marking (see note A) 2.03 ±.02
0.09 Max
4.8 Max 3.65 Typ
0.415 Min
PPaarrtt NNuummbbeerr RRaatteedd OOCCLL PPaarrtt IIrrmmss IIssaatt DDCCRR DDCCRR IInndduuccttaannccee μμHH ±± 2200%% MMaarrkkiinngg AAmmppss AAmmppss ΩΩ@@2200°°CC ΩΩ@@2200°°CC ((μμHH)) DDeessiiggnnaattoorr ((TTyyppiiccaall)) ((MMaaxxiimmuumm)) SSDD33881144 PPaarrtt NNuummbbeerr RRaatteedd OOCCLL PPaarrtt IIrrmmss IIssaatt DDCCRR IInndduuccttaannccee μμHH ±± 1155%% MMaarrkkiinngg AAmmppss AAmmppss ΩΩ ((μμHH)) DDeessiiggnnaattoorr TTyyppiiccaall SSDDHH33881122 SD3814
© 2008 Cooper B ussmann St. Lo uis, MO 63178 636-394-2877 www.cooperb ussmann.com Reorder # 4031 1008 PDF Only SD14 & SD25 Dimensions - mm 5.2 Max 5.2 Maxa HT 1.5 Typ. Ref. P i n#1 identifier Part marking (Note A) 2 R2.250 2.975 5.950 2.9752R2.250 5.959 1.0 2.9752 5.15 2.5752 5.9509 Top View Side View Bottom View Recommended Pad Layout
2 Pad Layout 4 Pad Layout
SD14 = 1.45mm Max SD25 = 2.5mm Max SSDD1144 && SSDD2255 PPaarrtt NNuummbbeerr RRaatteedd OOCCLL PPaarrtt IIrrmmss IIssaatt DDCCRR IInndduuccttaannccee ±± 2200%% MMaarrkkiinngg AAmmppss AAmmppss ΩΩ ((μμHH)) μμHH TTyyppiiccaall SD14-100-R 10 9.93 L 1.1 1.18 0.2058 SD14-220-R 22 21.93 N 0.806 0.793 0.3853 SD14-330-R 33 32.55 O 0.654 0.651 0.5852 SD14-470-R 47 47.57 P 0.525 0.538 0.9055 SD14-101-R 100 99.25 S 0.386 0.373 1.68 SD14-221-R 220 222 U 0.258 0.249 3.77 SD14-331-R 330 335.1 V 0.206 0.203 5.92 SD14-471-R 470 471.4 W 0.173 0.171 8.34 SD14-102-R 1000 1008 Z 0.126 0.117 15.8 SD25-101-R 100 100.79 R 0.670 0.398 0.5937 SD25-151-R 150 148.4 S 0.553 0.328 0.8723 SD25-221-R 220 222.4 T 0.446 0.268 1.34 SD25-331-R 330 332.2 U 0.359 0.219 2.07 SD25-471-R 470 472.4 V 0.293 0.184 3.10 NNoottee: SD10, 12, 18 and 20 not shown. For full product information and a listing of all available inductor values, see http://www.cooperbussmann.com/datasheets/elx, Data sheet number SD Series Typical SD Series Applications Mobile phones Digital cameras Industrial test equipment Computers Uninterruptible power supplies Televisions Typical SD Series Uses Buck and boost converters LED Drivers EL panel drivers Backlighting Noise filtering chokes The Cooper Bussmann Coiltronics® brand of magnetics specializes in standard and custom solutions, offering the latest in state-of-the-art low-profile high power density magnetic components. We remain at the forefront of i nnovation and new technology to deliver the optimal mix of packaging , high efficiency and unbeatable reliability. Our designs utilize high frequency, low core loss materials, and new and custom core shapes in combination with innovative construction and packaging to provide designers with the highest performance parts available on the market. The Coiltronics Brand product line of power magnetics continually expands to satisfy shifts in technology and related market needs. Standard Product Categories include: Shielded Drum Inductors Unshielded Drum Inductors High Current Inductors Toroidal Inductors Specialty Magnetics Custom Magnetics Please visit http://www.cooperbussmann.com/datasheets/elx to see data sheets on the wide variety of inductor solutions we have to offer. For techncial inquiries e-mail InductorTech@cooperindustries.com. Order samples online - www.cooperbussmann.com