ADP3170JRU Analog Devices, ADP3170JRU Datasheet - Page 9

• Manufacturer Part Number: ADP3170JRU
• Description: VRM 8.5 Compatible Single Phase Core Controller
• Manufacturer: Analog Devices

Designing an Inductor
Once the inductance is known, the next step is either to design
an inductor or find a standard inductor that comes as close as
possible to meeting the overall design goals. The first decision
in designing the inductor is to choose the core material. There
are several possibilities for providing low core loss at high fre-
quencies. Two examples are the powder cores (e.g., Kool-M
from Magnetics, Inc.) and the gapped soft ferrite cores (e.g.,
3F3 or 3F4 from Philips). Low frequency powdered iron cores
should be avoided due to their high core loss, especially when
the inductor value is relatively low and the ripple current is high.
Two main core types can be used in this application. Open
magnetic loop types, such as beads, beads on leads, and rods
and slugs, provide lower cost but do not have a focused mag-
netic field in the core. The radiated EMI from the distributed
magnetic field may create problems with noise interference in
the circuitry surrounding the inductor. Closed-loop types,
5V SB
12V
VTT PWRGD CLK
5V
MBR052LT1
MBR052LT1
D1
D2
1.7 H
L1
C6
4.7nF
1000 F
FROM
CPU
C1
C7
100nF
C8
100pF
1000 F
C2
10
1
2
3
4
5
6
7
8
9
VID3
VID2
VID1
VID0
VID25
PWRGD
REF
SD
FB
CS–
1000 F
ADP3170
1k
R1
C3
U1
LRDRV
COMP
PGND
DRVH
DRVL
LRFB
GND
1000 F
VCC
CS+
CT
C4
19
18
17
16
15
14
13
12
11
20
1000 F
C11
1nF
C19
150pF
C5
®
220
220
C
2.7nF
R4
R5
OC
Q1
FDB7045L
Q2
FDB7045L
1 H
such as pot cores, PQ, U, and E cores, or toroids, cost more, but
have much better EMI/RFI performance. A good compromise
between price and performance are cores with a toroidal shape.
There are many useful references for quickly designing a power
inductor. Table II gives some examples.
Magnetic Designer Software
Intusoft (http://www.intusoft.com)
Designing Magnetic Components for High-Frequency DC-DC
Converters
McLyman, Kg Magnetics
ISBN 1-883107-00-08
L1
C12
22 F
R
30.1k
1%
B
R6
2.5m
13.7k
1%
R
A
Table II. Magnetics Design References
C13 C14 C15 C16 C17 C18 C19 C20
RUBYCON ZA SERIES
24m
1000 F
ESR (EACH)
8
IRL3103
C22
68pF
Q6
5V SB
C23
220 F
10k
C21
1 F
R7
ADP3170
V
1.8V SB
1.8V, 200mA
CORE
PWRGD
TO CPU
1.05V – 1.825V
23A
V
CC(CORE)
CC(CORE)
RTN