參數(shù)資料
型號: LTC1574CS-5
廠商: LINEAR TECHNOLOGY CORP
元件分類: 穩(wěn)壓器
英文描述: High Efficiency Step-Down DC/DC Converters with Internal Schottky Diode
中文描述: 1 A SWITCHING REGULATOR, 200 kHz SWITCHING FREQ-MAX, PDSO16
封裝: 0.150 INCH, PLASTIC, SO-16
文件頁數(shù): 6/8頁
文件大?。?/td> 226K
代理商: LTC1574CS-5
6
LTC1574
LTC1574-3.3/LTC1574-5
APPLICATIO
S I
FOR
ATIO
U
inductor L1 is chosen for its excellent self-shielding prop-
erties. Open magnetic structures such as drum and rod
cores are to be avoided since they inject high flux levels
into their surroundings. This can become a major source
of noise in any converter circuit.
W
U
U
I
V
V
L
RIPPLE
OUT
D
=
+
)
4 10
6
A
P-P
Solving for L in the above equation and with V
D
= 0.5V,
L = 44
μ
H. The next higher standard value of L is 50
μ
H
(example: Coiltronics CTX50-4). The operating frequency,
ignoring voltage across diode V
D
is:
=
111
f
V
V
kHz
OUT
IN
2.
5
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
I
V
V
V
V
A
mA
RMS
OUT
OUT
IN
OUT
IN
RMS
=
(
)
]
(
)
=
1 2
/
174
For C
OUT
, the RMS current rating should be at least:
I
A
RMS
RMS
2
300mA
I
PEAK
(
)
=
TYPICAL APPLICATIO
N
S
Low Noise, High Efficiency 3.3V Regulator
V
IN
5
100pF
2, 4, 13, 15
6
12
11
7
10
3, 14
50
μ
H
0.1
μ
F
6.8nF
22
μ
F*
25V
×
2
1574 TA03
V
3.3V
450mA
56k
33k
V
IN
4V TO 12.5V
GND
LTC1574
I
PGM
LB
IN
LB
OUT
SHDN
V
FB
SW
*AVX TPSD226K025
*AVX TPSD107K010
COILTRONICS CTX50-4
+
+
100
μ
F**
10V
×
2
Design Example
As a design example, assume V
IN
= 9V (nominal),
V
OUT
= 5V and I
OUT
= 350mA maximum. The LTC1574-5
is used for this application with I
PGM
(Pin 6) connected to
V
IN
. The minimum value of L is determined by assuming
the LTC1574-5 is operating in continuous mode.
I
TIME
I
PEAK
I
V
AVG CURRENT= I
OUT
=
= 350mA
I
PEAK
+ I
V
2
1574 F06
Figure 6. Continuous Inductor Current
With I
OUT
= 350mA and I
PEAK
= 0.6A (I
PGM
= V
IN
), I
V
= 0.1A.
The peak-to-peak ripple inductor current, I
RIPPLE
, is 0.5A
and is also equal to:
相關PDF資料
PDF描述
LTC1574 High Efficiency Step-Down DC/DC Converters with Internal Schottky Diode(可調(diào)輸出,高效率步降DC/DC變換器(內(nèi)部帶肖特基二極管))
LTC1574-3.3 High Efficiency Step-Down DC/DC Converters with Internal Schottky Diode(3.3V,高效率步降DC/DC變換器(內(nèi)部帶肖特基二極管))
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