LTC1174
LTC1174-3.3/LTC1174-5
APPLICATIO S I FOR ATIO
Solving for L in the above equation and with V
D
= 0.6V,
L = 44.8µH. The next higher standard value of L is 50µH
(example: Coiltronics CTX50-4). The operating frequency,
neglecting voltage across diode V
D
is:
⎛
V
⎞
f
≈
2.5 • 10
5
1
−
OUT
⎜
⎝
⎟
V
IN
⎠
=
111kHz
With the value of L determined, the requirements for C
IN
and C
OUT
are calculated. For C
IN
, its RMS current rating
should be at least:
I
RMS
=
I
OUT
V
OUT
(
V
IN
−
V
OUT
)
V
IN
[
]
1/ 2
(
A
RMS
)
=
174mA
For C
OUT
, the RMS current rating should be at least:
I
RMS
≈
I
PEAK
(
A
RMS
)
2
=
300mA
12
U
Now allow V
IN
to drop to 6V. At this minimum input voltage
the operating frequency will decrease. The new frequency
is 42kHz.
Table 1. Inductor Manufacturers
MANUFACTURER
Coilcraft
1102 Silver Lake Road
Cary, IL 60013
(708) 639-2361
Coiltronics Inc.
6000 Park of Commerce Blvd.
Boca Raton, FL 33487
(407) 241-7876
Gowanda Electronics Corporation
1 Industrial Place
Gowanda, NY 14070
(716) 532-2234
Sumida Electric Co. Ltd.
637 E. Golf Road, Suite 209
Arlington Heights, IL 60005
(708) 956-0666/7
PART NUMBER
DT3316 Series
Econo-Pac
Octa-Pac
GA10 Series
CD 54 Series
CD 75 Series
W
U U
Table 2. Capacitor Manufacturers
MANUFACTURER
AVX Corporation
P.O. Box 887
Myrtle Beach, SC 29578
(803) 448-9411
Nichicon America Corporation
927 East State Parkway
Schaberg, IL 60173
(708) 843-7500
Sanyo Video Components
2001 Sanyo Avenue
San Diego, CA 92173
(619) 661-6385
Attn: Sales Dept.
PART NUMBER
TPS Series
TAJ Series
PL Series
OS-CON Series
1174fe
LINEAR [ LINEAR INTEGRATED SYSTEMS ]
