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參數(shù)資料
| 型號： | SC2441A |
| 廠商： | Semtech Corporation |
| 英文描述： | 1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter |
| 中文描述： | 1.8V至20V的輸入2相同步降壓與升壓轉(zhuǎn)換器控制器 |
| 文件頁數(shù)： | 22/37頁 |
| 文件大?。?/td> | 1024K |
| 代理商： | SC2441A |
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22
2006 Semtech Corp.
www.semtech.com
POWER MANAGEMENT
Applications Information
SC2441A
Assuming that the efficiency of the boost converter is
η
and the boost converter is running in CCM with duty ratio
D. The peak inductor current is
The saturation current rating of the selected inductor
should be at least 1.2 times of the calculated peak
current value.
Step-up Converter Capacitor Selection
Input capacitor
: The input capacitance should be large
such that the input transients due to both the step-up
and the step-down converters do not trip the UVLO
threshold 1.71V. Since the SC2441A controls a 2-phase
low input voltage step-down converter, the input
capacitance is sized to handle the input ripple current of
the buck converter. This is usually sufficient for the
auxiliary boost converter because the input current in a
boost converter is continuous.
Output capacitor:
Unlike buck converter, pulse current
is delivered to the output of a boost converter. To reduce
the output ripple voltage, low ESR capacitors should be
used. The output capacitor should also be able handle
the output ripple current. The SC2441A is designed to
use multi-layer ceramic capacitor as the sole output
capacitor.
Maximum Output Current of the Step-up Converter
Figure 3 shows that the boost switch current is sensed
with an internal sense resistor Rs and it is internally
limited at 0.6A. So the maximum output current can be
given as (
η
is the efficiency of the step-up section):
o3
in
V
3
max
o3,
I
V
2
0.6A
)
(
SW3
PGND2
SC2441A
27
26
L
1
D
1
C
1
C
2
R
1
V
CC
PGND1
V
IN
21
24
Small
Loop
Figure 9. Step-Up Section Layout Illustration
As shown in Figure 9, to minimize the switching noise
generated by the step-up converter, the loop formed by
D
, C
, SW3 and PGND2 should be as small as possible.
And the PGND2 pin should be tied to PGND1 at one
spot close to the PGND1 pin.
Step-up Converter Inductor Selection
For a specified inductor current ripple ratio
δ
(peak-to-
peak current ripple v.s. actual input current I
IN
), the
inductor value is
.
V
V
)
V
V
1
I
f
V
L
3
o
in
3
o
in
3
o
3
3
s
in
1
Typically, select
δ
3
<2 for a Continous Conduction Mode
(CCM) operation.
If V
= 3.3V, V
= 5V and I
o3
= 100mA with
δ
3
= 1.6 and
f
s3
= 1MHz, then, L
1
= 4.7
μ
2
1
T
D
L
V
V
I
V
I
1
in
in
o3
o3
L1PEAK
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SC2441AEVB | 1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter |
| SC2441ATETRT | 1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter |
| SC2441 | Very Low Input Voltage 2-Phase Synchronous Step-down Controllers with Step-up Converter |
| SC2441EVB | Very Low Input Voltage 2-Phase Synchronous Step-down Controllers with Step-up Converter |
| SC2441ITSTRT | Very Low Input Voltage 2-Phase Synchronous Step-down Controllers with Step-up Converter |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SC2441A_09 | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter |
| SC2441AEVB | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter |
| SC2441ATETRT | 制造商:Semtech Corporation 功能描述: |
| SC2441EVB | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:Very Low Input Voltage 2-Phase Synchronous Step-down Controllers with Step-up Converter |
| SC2441ITSTRT | 制造商:Semtech Corporation 功能描述:Controller IC |
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