參數(shù)資料
型號: FAN4855
廠商: Fairchild Semiconductor Corporation
英文描述: 500mA High Efficiency Boost Regulator with Adjustable Output, Shutdown and Low Battery Detect
中文描述: 500mA的高效率升壓可調(diào)輸出,關(guān)機(jī)和低電池檢測穩(wěn)壓器
文件頁數(shù): 10/13頁
文件大小: 148K
代理商: FAN4855
PRODUCT SPECIFICATION
FAN4855
10
REV. 1.0.0 3/17/04
Layout and Grounding
Considerations
Careful design of printed circuit board is recommended since
high frequency switching and high peak currents are present
in DC/DC converters applications. A general rule is to place
the converter circuitry well away from any sensitive analog
components. The printed circuit board layout should be
based on some simple rules to minimize EMI and to ensure
good regulation performances:
1.
Place the IC, inductor, input and output capacitor as
close together as possible.
2.
Keep the output capacitor as close to the FAN4855 as
possible with very short traces to V
OUT
and GND pins.
Typically it should be within 0.25 inches or 6 mm.
3.
Keep the traces for the power components wide,
typically > 50 mils or 1.25 mm.
4.
Place the external networks for LBI and FB close to
FAN4855, but away from the power components as far
as possible to prevent voltage transient from coupling
into sensitive nodes.
5.
On multilayer boards use component side copper for
grounding around the IC and connect back to a quiet
ground plane using vias. The ground planes act as
electromagnetic shields for some of the RF energy
radiated.
6.
The connection of the GND pin of the IC (pin 8) to the
overall grounding system should be directly to the
bottom of the output filter capacitor. A star grounding
system radiating from where the power enters the PCB,
is a recommended practice.
Application Example
The FAN4855 can be used as a constant current source to
drive white LEDs like QTLP670C-IW. As shown in the
diagram below, the current is maintained constant over a
wide range of input voltages.
L = 10μH
D1
FAN4855
1
2
3
4
8
7
6
5
D2
Cout
10μF
Cin
10μF
+
+
+
D3
D4
62
62
62
62
20
Input Voltage (V)
L18.4
18.2
19.6
19.4
19.2
19
18.8
18.6
18
0
1
2
3
4
5
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參數(shù)描述
FAN4855MTC 功能描述:直流/直流開關(guān)調(diào)節(jié)器 Adj 2-Cell Boost RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
FAN4855MTCX 功能描述:直流/直流開關(guān)調(diào)節(jié)器 Adj 2-Cell Boost RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
FAN4855MTCX 制造商:Fairchild Semiconductor Corporation 功能描述:DC/DC Converter IC
FAN4855MU 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:500mA High Efficiency Boost Regulator with Adjustable Output, Shutdown and Low Battery Detect
FAN4855MUX 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:500mA High Efficiency Boost Regulator with Adjustable Output, Shutdown and Low Battery Detect