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參數資料
| 型號： | SC2441 |
| 廠商： | Semtech Corporation |
| 英文描述： | Very Low Input Voltage 2-Phase Synchronous Step-down Controllers with Step-up Converter |
| 中文描述： | 非常低的輸入電壓2相同步降壓與升壓轉換器控制器 |
| 文件頁數： | 27/35頁 |
| 文件大?。?/td> | 733K |
| 代理商： | SC2441 |
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27
2005 Semtech Corp.
www.semtech.com
POWER MANAGEMENT
Applications Information (Cont.)
SC2441
4) Shorten the gate driver path. Integrity of the gate drive
(voltage level, leading and falling edges) is important for
circuit operation and efficiency. Short and wide gate drive
traces reduce trace inductances. Bond wire inductance is
about 2~3nH. If the length of the PCB trace from the gate
driver to the MOSFET gate is 1 inch, the trace inductance
will be about 25nH. If the gate drive current is 2A with
10ns rise and falling times, the voltage drops across the
bond wire and the PCB trace will be 0.6V and 5V
respectively. This may slow down the switching transient of
the MOSFET’s. These inductances may also ring with the
gate capacitance.
5) Put the decoupling capacitor for the gate drive power
supplies (BST and VCC) close to the IC and power ground.
Control Section
6) The frequency-setting resistor Rosc should be placed
close to Pin 10. Trace length from this resistor to the analog
ground should be minimized.
7) Solder the VCC decoupling capacitor next to the VCC
and power ground PGND pins.
8) Place the combi-sense components away from the power
circuit and close to the corresponding CS+ and CS- pins.
Use X7R type ceramic capacitors for combi-sensing due
to their thermal stability.
9) Use an isolated local ground plane for the controller
and tie it to the negative side of output capacitor bank.
PC Board Layout Issues
Circuit board layout is very important for the proper
operation of high frequency switching power converters. A
power ground plane is required to reduce ground bounces.
The followings are suggested for proper layout.
Power Stage
1) Separate the power ground from the signal ground. In
SC2441 the power ground PGND should be tied to the
source terminal of lower MOSFETs. The signal ground AGND
should be tied to the negative terminal of the output
capacitor (ouput return terminal).
2) Minimize the size of pulse current loop. Place the top
MOSFET, the bottom MOSFET and the input capacitors
close to each other with short and wide traces. In addition
to the aluminum energy storage capacitors, add multi-layer
ceramic (MLC) capacitors from the input to the power
ground to improve high frequency bypass.
3) Reduce high frequency voltage ringing. Widen and
shorten the drain and source traces of the MOSFET’s to
reduce stray inductances. Add a small RC snubber if
necessary to reduce the high frequency ringing at the phase
node. Sometimes slowing down the gate drive signal also
helps in reducing the high frequency ringing at the phase
node.
A note for Vin = 12V application
Figure 21 shows an application where the input voltage is 12V. A LDO is used to provide 5V bias for SC2441. The
voltages at BST1 (Pin 25) and BST2 (Pin 18) should not exceed their maximum voltage rating (20V).
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| 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 |
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相關代理商/技術參數 |
參數描述 |
|---|---|
| SC2441A | 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 |
| 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 |
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