Application Note

VISHAY DALE
www.vishay.com
Magnetics
Application Note
IHLP Selection Example
INPUT
LREQ
IDC
I
Freq.
TAMB
V-μs

0.54 μH
20 A
7.39 A
300 kHz
50 °C
4.14
0.46
IHLP SELECTED
Step 1.
IHLP-4040DZ-01 0.56 μH
L
DCR
IHEAT
ISAT
RTH
PHEAT
ET100
K0
K1
0.56 μH
0.0017 
30 A
49 A
26.96 °C/W
1.48 W
0.88
18.31
0.00340
VERIFICATION
Step 2.
B PK
OPER
4.14
= ----------- x 100 = 470.5 G
0.88
Step 3.
300 000
f e = ---------------------------------------------- = 192 216.1 Hz
2
2  0.46 – 0.46 
Step 4.
PCORE = 18.31 x 192 2160.188 x 470.52.118 x 300 000 x 10-14 = 0.248 W
Step 5.
The core losses are 0.248 W which is less then 1/3 of PHEAT (0.493 W)
Step 6.
PCUallowed = 1.48 - 0.248 = 1.32 W
Step 7.
274.5 + 50
R OPER = 0.0017 x ---------------------------- = 0.00213 
259.5
2
P DC = 20 x 0.00213 = 0.852 W
300 000 x 0.00213 = 0.217 W
Step 8.
PTOTAL = 0.248 + 0.852 + 0.217 = 1.317 W
Step 9.
T = 1.317 x 26.96 = 35.51 °C
TOPER = 50 + 35.51 = 85.51 °C
Step 10.
7.39
I PEAK = 20 + ----------- = 23.7 A
2
ISAT = 49 A which is greater then the required 23.7 A
Revision: 20-Mar-13
Document Number: 34252
1
For technical questions, contact: magnetics@vishay.com
THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT
ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
APPLICATION NOTE
2
P AC = 0.00340 x 7.39 x
Application Note
www.vishay.com
Vishay Dale
IHLP Selection Example
SELECTION CRITERIA
1. Limit core losses (PCORE) to  1/3 of total losses for 40 °C temperature rise (PHEAT).
2. Total copper losses allowed will be equal to PHEAT - PCORE.
3. Maximum component temperature should be kept  125 °C, 155 °C for -51 components.
4. Maximum T should be  40 °C (this can be exceeded provided caution is taken to insure max. temperature  125 °C/155 °C).
5. IPEAK  ISAT (recommended, IPEAK can exceed ISAT with caution due to soft saturation of IHLP product).
GOVERNING EQUATIONS
ET ckt
= --------------- x 100
ET 100
G
1.
B PK
2.
f0
f e = ---------------------------2
2   –  
3.
P CORE = K 0 f e
4.
P AC = K 1 x I x
5.
274.5 + T AMB
R OPER = R TYP. x -----------------------------------259.5
OPER
Kf – 1
2
 Hz 
B pk
Kb
x f 0 x 10
f 0 x R OPER
– 14
W
W
A
2
W
6.
P DC = I
7.
P TOTAL = P CORE + P DC + P AC
8.
T = P TOTAL x R TH
 C 
9.
T OPER = T AMB + T
 C 
DC
x R OPER
I
10. I PEAK = I DC + ----2
W
A
Notes
(1) Equation #5 assumes a 40 °C temperature rise and will have the same units as R
TYP.
(2) For equations #3 f in Hz and B
PK in G.
(3) R
OPER is based on a 40 °C temperature rise.
(4) K is 1.188 for -01 material, 1.173 for -11 material, and 1.044 for -51 material.
f
(5) K is 2.118 for -01 material, 2.213 for -11 material, and 2.497 for -51 material.
b
(6) For IHLP-2525EZ-01 - K = 1.181 and K = 2.166.
f
b
SELECTION PROCESS
APPLICATION NOTE
Note
• This process assumes that the following is known: Required inductance, frequency, IDC, I, TAMB, and V-μs (ET) required.
Step 1.
Select inductor value based on controller data
sheet recommendation and current (IDC) rating.
Step 6.
Use selection criteria #2 to determine allowable
copper losses.
Step 2.
Determine peak operational flux density in Gauss
using equation #1.
Step 7.
Determine actual copper losses using equations
#4, #5 and #6.
Step 3.
Calculate effective frequency using equation #2.
Step 8.
Use equation #7 for total losses.
Step 4.
Determine core loss using equation #3 (see notes
#1 and #2) and compare to selection criteria #1.
Step 9.
Step 5.
If core losses are > 1/3 PHEAT select a larger
inductor.
Determine T using equation #8 and insure
TOPER  125 °C (155 °C for -51 material) using
equation #9.
Step 10. Verify IPEAK is less then ISAT using equation #10 for
the selected part (see selection criteria #5).
DEFINITIONS
ETckt V-μs product of the circuit
f0
Switching frequency in Hz
ET100 V-μs product at 100 Gauss from table #1
RTH
Thermal gradient of IHLP from Table #1
PCORE Core losses in W
fe
Effective frequency in Hz
PDC
Losses due to the DCR of the inductor copper
winding in W

Duty cycle
PAC-
Losses in the coil due to AC effects
K0
IHLP core constant from table #1
K1-
AC loss constant from Table #1
Revision: 20-Mar-13
Document Number: 34252
2
For technical questions, contact: magnetics@vishay.com
THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT
ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000