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© Coilcraft, Inc. 2009
Hexa-Path Magnetics
Document 613-6
Revised 01/23/09
Document 613-6
Inductors – using multiple windings
DCR
Volt-time
Peak energy
Part
Inductance
max
product
storage
Isat
Irms
number
(µH)
(Ohms)
(V-µsec)
(µJ)
(A)
(A)
HP3-0138L_
11.2 ±20%
0.055
30.4
1.656
0.650
1.73
Connecting windings in series
For higher inductance, the windings can be connected in series. As inductance
increases, energy storage and
Irms remain the same, but DCR increases and
Isat decreases.
Example: Calculate new electricals for HP3-0138L with four windings (Wn)
connected in series:
Inductance = Inductancetable × Wn2
= 11.2 × 42 = 179.2 µH
DCR = DCRtable × Wn
= 0.055 × 4 = 0.22 Ohms
Isat = (Isattable) × 6
÷ Wn
= (0.65 × 6)
÷ 4 = 0.975 A
Irms = Irmstable = 1.73 A
Connecting windings in parallel
To increase current ratings, the windings (Wn) can be connected in parallel.
DCR decreases, current ratings increase, and inductance remains the same.
Example: Calculate new electricals for HP5-0083L, with three (Wn) windings
connected in parallel (equivalent to one winding in series):
Inductance = Inductancetable
= 11.2 µH
DCR = 1
÷ [Wn × (1 ÷ DCRtable)]
= 1
÷ [3 × (1 ÷ 0.045)] = 0.015 Ohms
Isat = (Isattable × 6)
÷ Wn
= (0.65 × 6)
÷ 1 = 3.9 A
Irms = Irmstable × Wn
= 1.73 × 3 = 5.19 A
1
2
3
9
4
12
11
10
8
7
5
6
L = 179.2 µH
DCR = 0.22
Isat = 0.975 A
Irms = 1.73 A
Formulas used to calculate electrical characteristics
Connecting windings in series
Inductance = Inductancetable × (number of windings)2
DCR = DCRtable × number of windings
Isat = (Isattable × 6)
÷ number of windings connected in series
Irms = Irmstable
Connecting windings in parallel
Inductance = Inductancetable
DCR = 1
÷ [number of windings × (1 ÷ DCRtable)]
Isat = (Isattable × 6)
÷ number of windings connected in series
Irms = Irmstable × number of windings
1
2
3
9
4
12
11
10
8
7
5
6
L = 11.2 µH
DCR = 0.015
Isat = 3.9 A
Irms = 5.19 A