參數(shù)資料
型號: LTC1627
廠商: Linear Technology Corporation
英文描述: Monolithic Synchronous Step-Down Switching Regulator(單片同步步降開關穩(wěn)壓器)
中文描述: 單片同步降壓型開關穩(wěn)壓器(單片同步步降開關穩(wěn)壓器)
文件頁數(shù): 12/16頁
文件大?。?/td> 228K
代理商: LTC1627
12
LTC1627
3. Does the (+) plate of C
IN
connect to V
IN
as closely as
possible This capacitor provides the AC current to the
internal power MOSFETs.
4. Keep the switching node SW away from sensitive small-
signal nodes.
Design Example
As a design example, assume the LTC1627 is used in a
single lithium-ion battery-powered cellular phone applica-
tion. The V
IN
will be operating from a maximum of 4.2V
down to about 2.7V. The load current requirement is a
maximum of 0.5A but most of the time it will be on standby
mode, requiring only 2mA. Efficiency at both low and high
load currents is important. Output voltage is 2.5V. With
this information we can calculate L using equation (1),
L
f
I
V
V
V
L
OUT
OUT
IN
=
( )(
)
1
1
(3)
Substituting V
OUT
= 2.5V, V
IN
= 4.2V,
I
L
= 200mA and
f = 350kHz in equation (3) gives:
L
V
200
kHz
mA
V
V
H
=
(
)(
)
=
2 5
350
1
2 5
4 2
14 5
A 15
μ
H inductor works well for this application. For good
efficiency choose a 1A inductor with less than 0.25
series resistance.
C
IN
will require an RMS current rating of at least 0.25A at
temperature and C
OUT
will require an ESR of less than
0.25
. In most applications, the requirements for these
capacitors are fairly similar.
For the feedback resistors, choose R1 = 80.6k. R2 can then
be calculated from equation (2) to be:
R
V
R
k
OUT
0 8
2
1
1 171
=
;
use 169k
Figure 8 shows the complete circuit along with its effi-
ciency curve.
C
SS
0.1
μ
F
C
OUT
100
μ
F
6.3V
C
IN
22
μ
F
16V
C1
0.1
μ
F
C2
0.1
μ
F
D2
D1
BAT54S**
15
μ
H*
* SUMIDA CD54-150
** ZETEX BAT54S
AVX TPSC107M006R0150
AVX TPSC226M016R0375
R2
169k
1%
R1
80.6k
1%
C
47pF
1
2
3
4
8
7
6
5
SYNC/FCB
V
DR
V
IN
SW
I
TH
RUN/SS
V
FB
GND
LTC1627
V
2.8V TO
4.5V
V
2.5V
0.5A
1627 F08a
+
+
OUTPUT CURRENT (mA)
E
1
100
1000
1627 F08b
10
100
95
90
85
80
75
70
65
60
55
50
45
V
OUT
= 2.5V
V
IN
= 3.6V
V
IN
= 4.2V
Figure 8. Single Lithium-Ion to 2.5V/0.5A Regulator
APPLICATIOU
W
U
U
相關PDF資料
PDF描述
LTC1628-SYNC High Efficiency, 2-Phase Synchronous Step-Down Switching Regulator
LTC1628-PG RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS
LTC1628I-PG RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS
LTC1628C RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS
LTC1628C-PG RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS
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