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參數資料
| 型號： | SC2441ATETRT |
| 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換器控制器 |
| 文件頁數： | 21/37頁 |
| 文件大?。?/td> | 1024K |
| 代理商： | SC2441ATETRT |
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21
2006 Semtech Corp.
www.semtech.com
POWER MANAGEMENT
Applications Information
SC2441A
switching frequency and very short duty cycle is not
practical. If the input voltage is 3.3V and the operating
frequency is 1MHz, the lowest output voltage will be 0.6V.
There will not be enough modulation headroom if the on
time is simply made equal to the minimum on time of the
SC2441A. For ease of control, we recommend that the
required pulse width be at least 1.5 times the minimum
on time.
Maximum Duty-cycle Consideration
The top MOSFET turns off for at least 200ns every cycle
regardless of the switching frequency. This places an
upper bound on the voltage conversion ratio at a given
switching frequency.
If the desired output voltage requires high operating duty-
cycle, then operating frequency will have to be lowered
to allow modulating headroom.
RC Filtering network for V
CC
and V
IN
pins
A RC filtering network is recommended for the SC2441A
V
CC
and V
IN
pin connections. As shown in Figure 1, R
6
plus
C
and R
plus C
are the filtering networks for V
pin
and V
pin respectively. The value of the R
and R
ranges
from 3.3
to 5.11
.
C
8
and C
2
should be larger than
1
μF
.
C
and C
are the decoupling capacitors for the V
pin
and V
pin. They should be placed as close as possible
to the pins of the SC2441A to achieve the best
decoupling performance. Due to the different
functionalities of the V
pin and V
pin, C
should be
placed between the V
pin and the signal ground of the
SC2441A. And C
should be placed between the V
pin
and the power ground of the SC2441A. The
recommended connections for the V
CC
pin and V
IN
pin are
illustrated in Figure 8.
V
IN
GND
PGND1
SC2441A
9
24
V
CC
1
21
C
2
C
8
R
2
R
6
Figure 8. RC Network Connections for V
IN
and V
CC
pins
Step-Up Converter
The SC2441A features a step-up regulator and two step-
down controllers.
The boost section of the SC2441A comprises of pins 7,
8, 26 and 27. Pin 26 is the independent power ground
for the boost converter section, which should be
separated from the step-down section power ground pin
24 in layout to minimize the noise influence. The boost
section in SC2441A has an internal reference set at
1.25V. The output of the boost section can be
programmed with external resistors R
1
and R
4
as shown
in Figure 1.
4
4
1
BOOST
V
R
R
R
1.25V
SC2441A utilizes a transconductance error amplifier for
the step-up controller and it can be compensated with
C
, R
and C
as shown in Figure 1. The step-up controller
in the SC2441A employs cycle-by-cycle peak current limit
to protect the internal switching transistor. Current limit
threshold is typically 0.8A.
In the applications where only low input voltage is
available, the step-up converter in the SC2441A is very
useful for generating an auxiliary output to power the
gate drive of the step-down controllers.
相關PDF資料 |
PDF描述 |
|---|---|
| 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 |
| SC2442 | High Performance Wide Input Range Dual Synchronous Buck Controller |
| SC2442H | High Performance Wide Input Range Dual Synchronous Buck Controller |
相關代理商/技術參數 |
參數描述 |
|---|---|
| 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 |
| SC2442 | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:High Performance Wide Input Range Dual Synchronous Buck Controller |
| SC2442H | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:High Performance Wide Input Range Dual Synchronous Buck Controller |
| SC2442HITSTR | 制造商:Semtech Corporation 功能描述: |
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