LX1710-1 Microsemi Corporation, LX1710-1 Datasheet - Page 12

• Manufacturer Part Number: LX1710-1
• Description: EVALUATION KIT
• Manufacturer: Microsemi Corporation

LXE1710 E
I
The output filter inductors are key elements in the
performance of the Class-D audio power amplifier.
Inductor selection criteria also involves tradeoffs
between performance (efficiency) and component
costs. The critical specifications for the inductor are
the DC resistance, DC current, and peak current
ratings. The inductors should be able to handle the
amplifier’s power as well as operate within its linear
region.
performance (increase THD) and even produce a
short, which may damage either the circuit or the
speaker.
Other variables when selecting an inductor depend on
the switching frequency of the designed amplifier. A
higher switching frequency implies that the corner
frequency of the LC filter is higher. With a higher f
the inductor value is smaller.
The amplifier’s application and design constraints will
help determine whether the inductors are selected for
size, power, or performance. Various inductors such
as those that are shielded may also have different EMI
effects and distortion performance.
The overall efficiency (
) of the amplifier circuit is given
in the previous MOSFET section.
power loss contribution is a function of the inductor’s
DC resistance, R
NDUCTOR
Copyright
Rev. 1.1, 2000-12-01
Manufacturer

 
Coilcraft
ISI
S
Saturating the inductors could decrease
Inductor Component Options
ELECTION
2000
VALUATION
IND
.
DO5022P-153HC
Part Number
RL622-150K
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: [phone]
B
OARD
Inductance
The inductor’s

15.0
15.0
Linfinity Microelectronics Division
Microsemi
Q min
50
C
,
Frequency
2.520MHz
100kHz
Test
      
The LX1710 Evaluation board utilizes two 15µH radial
leaded R.F. inductors from Inductor Supply, Inc. (ISI).
When evaluating component options, inductors such
as from Coilcraft can be used for other performance /
price tradeoffs. See inductor table below.
The efficiency approximation can now be completed.
The efficiency is a function of the power and switching
loss in the MOSFETs and inductors.






Inductor
. 1
P
P
P
OUT
DS
56
IN
DC Resistance
P
P
7 .
 
IND
25
IND
I
Power
2
56
32
.
[
45
I
( 2
2
2 (
P
R
R
CROSS
L
5 .
NDS
Loss
25
2
)(
DC Current
2


max (A
R
)(.
I
PDS
P
90
2.50
056
2
4.4
IND
R
I
2 .
L
RMS
2
)
U
%
R
R
)
(
L
IND
SER
I
0
2
7 .
Frequency min
)
Self Resonant
)(
W
2
G
R
)(
(MHz)
12.0
L
R
20
UIDE
]
Page 12
IND
P
)
CROSS