SMD Toroidal Power Choke

West Coast Magnetics' high frequency inductors are designed for use as filters in high frequency power supplies. They will handle significant amounts of DC and will attenuate frequencies as high as 500 MHz. The winding has been optimized to maximize the inductance and minimize the losses under load. The parts are used in a wide variety of power supply topologies and are ideal for use in computer and related applications.

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Design Constants

Part Number	Inductance, no DC(µH)	Max DCR (milliohms)	Rated DC Current (amps) a.	Nominal Energy Storage at Rated Load (µJ) b.	Inductance at Rated Load (µH) b.	ET at 50 kHz c.	ET at 100 kHz c.	ET at 250 kHz c.	ET at 500 kHz c.	Coil Size Code
304-01	8.5	117	0.8	2.4	7.4	10.1	6.8	4.0	2.6	SM 1
304-02	15.8	160	0.8	4.0	12.5	13.8	9.3	5.4	3.6	SM 1
304-03	61.8	370	0.8	16	49.4	41.4	27.5	15.8	10.4	SM 2
304-04	149.5	374	0.8	32	100.2	64.4	42.7	24.5	16.1	SM 2
304-05	291.6	1093	0.8	71	221.6	141.9	93.1	54.5	36.7	SM 5
304-06	3.4	49	1.0	1.6	3.1	6.4	4.3	2.5	1.7	SM 1
304-07	5.1	59	1.0	2.2	4.5	7.8	5.3	3.1	2.0	SM 1
304-08	29.6	158	1.0	13	25.5	28.5	18.9	10.8	7.1	SM 2
304-09	105.9	370	1.0	42	84.7	74.3	49.0	28.6	19.3	SM 4
304-10	190.6	554	1.0	72	144.9	114.8	75.2	44.1	29.6	SM 5
304-11	1.8	23	1.4	1.6	1.7	4.6	3.1	1.8	1.2	SM 1
304-12	19.1	86	1.4	15	15.7	23.0	15.3	8.8	5.8	SM 2
304-13	35.6	132	1.4	27	27.8	36.6	24.1	14.1	9.3	SM 3
304-14	64.7	185	1.4	49	49.8	58.1	38.3	22.4	15.1	SM 4
304-15	9.9	40	2.0	16	8.0	16.6	11.0	6.3	4.1	SM 2
304-16	23.7	66	2.0	38	19.0	32.6	21.6	12.5	8.4	SM 3
304-17	40.5	94	2.0	60	30.0	45.9	30.3	17.7	11.9	SM 4
304-18	66.8	135	2.0	94	46.8	68.0	45.0	26.1	17.6	SM 5
304-19	6.9	22	2.8	21	5.2	13.8	9.2	5.3	3.5	SM 2
304-20	11.0	29	2.8	35	9.0	22.2	14.7	8.6	5.7	SM 3
304-21	21.9	45	2.8	62	16.0	33.8	22.3	13.0	8.8	SM 4
304-22	45.2	72	2.8	116	29.8	55.9	37.0	21.5	14.4	SM 5
304-23	3.7	11	4.0	22	2.8	10.1	6.7	3.9	2.5	SM 2
304-24	5.9	15	4.0	35	4.4	14.9	9.8	5.7	3.8	SM 3
304-25	14.0	23	4.0	76	9.5	27.0	17.8	10.4	7.0	SM 4
304-26	20.6	31	4.0	110	13.8	37.8	25.0	14.5	9.8	SM 5
304-27	2.6	6.5	5.7	31	1.9	9.9	6.5	3.8	2.5	SM 3
304-28	5.0	9.2	5.7	59	3.7	16.2	10.7	6.2	4.2	SM 4
304-29	9.5	14	5.7	103	6.4	25.7	17.0	9.9	6.6	SM 5
304-30	16.0	18	5.7	153	9.4	33.2	22.0	12.8	8.6	SM 5

a. Current rating for maximum T rise of 40 degrees C.

b. Energy storage and inductance at rated load assume ripple current less than 1% of rated DC current.

c. Volt Microseconds for 15 degree C T rise due to core losses.

pcb layouts

click image to enlarge

Size/Code	A	B	C	D	E	F
SM 1	.340/8.64	.340/8.64	.270/6.86	.270/6.86	.300/7.62	.060/1.52
SM 2	.485/11.05	.440/11.18	.360/9.14	.360/9.14	.400/10.16	.060/1.52
SM 3	.560/14.22	.565/14.35	.360/9.14	.460/11.68	.520/13.21	.060/1.52
SM 4	.590/14.99	.615/15.62	.400/10.16	.510/12.95	.550/13.97	.060/1.52
SM 5	.670/17.02	.700/17.78	.400/10.16	.590/14.99	.620/15.75	.060/1.52

Dimensions A, B, C are maximum dimensions.

Recommended tolerance on dimensions D, E = ±.005/.13

Maximum Rise = .010/.25

Moulding: Ryton R4
Rating: UL 94 V0
SMD Pads: Sn96.5/Ag3.0/Cu0.5