參數(shù)資料
型號(hào)： LP3954
廠商： National Semiconductor Corporation
英文描述： Advanced Lighting Management Unit
中文描述： 高級(jí)照明管理單位
文件頁(yè)數(shù)： 34/56頁(yè)
文件大小： 5801K
代理商： LP3954
Recommended External
Components
OUTPUT CAPACITOR, C
OUT
The output capacitor C
directly affects the magnitude of
the output ripple voltage. In general, the higher the value of
C
, the lower the output ripple magnitude. Multilayer ce-
ramic capacitors with low ESR are the best choice. At the
lighter loads, the low ESR ceramics offer a much lower Vout
ripple that the higher ESR tantalums of the same value. At the
higher loads, the ceramics offer a slightly lower Vout ripple
magnitude than the tantalums of the same value. However,
the dv/dt of the Vout ripple with the ceramics is much lower
that the tantalums under all load conditions. Capacitor voltage
rating must be sufficient, 10V or greater is recommended.
Some ceramic capacitors, especially those in small pack-
ages, exhibit a strong capacitance reduction with the
increased applied voltage. The capacitance value can fall
to below half of the nominal capacitance. Too low output
capacitance will increase the noise and it can make the
boost converter unstable.
INPUT CAPACITOR, C
IN
The input capacitor C
IN
directly affects the magnitude of the
input ripple voltage and to a lesser degree the V
ripple. A
higher value C
will give a lower V
ripple. Capacitor voltage
rating must be sufficient, 10V or greater is recommended.
OUTPUT DIODE, D
OUT
A Schottky diode should be used for the output diode. To
maintain high efficiency the average current rating of the
schottky diode should be larger than the peak inductor current
(1A). Schottky diodes with a low forward drop and fast switch-
ing speeds are ideal for increasing efficiency in portable ap-
plications. Choose a reverse breakdown of the schottky diode
larger than the output voltage. Do not use ordinary rectifier
diodes, since slow switching speeds and long recovery times
cause the efficiency and the load regulation to suffer.
INDUCTOR, L
1
The LP3954’s high switching frequency enables the use of
the small surface mount inductor. A 4.7 μH shielded inductor
is suggested for 2 MHz operation, 10 μH should be used at 1
MHz. The inductor should have a saturation current rating
higher than the peak current it will experience during circuit
operation
(1A)
. Less than 300 m
ESR is suggested for high
efficiency. Open core inductors cause flux linkage with circuit
components and interfere with the normal operation of the
circuit. This should be avoided. For high efficiency, choose an
inductor with a high frequency core material such as ferrite to
reduce the core losses. To minimize radiated noise, use a
toroid, pot core or shielded core inductor. The inductor should
be connected to the SW pin as close to the IC as possible.
LIST OF RECOMMENDED EXTERNAL COMPONENTS
Symbol
C
VDD1
C
VDD2
C
VDDIO
C
VDDA
C
OUT
C
IN
L
BOOST
C
VREF
C
VDDIO
R
FLASH
R
RBG
R
RT
D
OUT
C
ASE
LEDs
D
LIGHT
Symbol explanation
C between VDD1 and GND
Value
100
Unit
nF
Type
Ceramic, X7R / X5R
C between VDD2 and GND
100
nF
Ceramic, X7R / X5R
C between VDDIO and GND
100
nF
Ceramic, X7R / X5R
C between VDDA and GND
1
μF
Ceramic, X7R / X5R
C between FB and GND
10
μF
Ceramic, X7R / X5R, 10V
C between battery voltage and GND
10
μF
Ceramic, X7R / X5R
L between SW and V
BAT
at 2 MHz
C between V
REF
and GND
C between V
DDIO
and GND
R between I
FLASH
and GND
R between I
RGB
and GND
R between I
RT
and GND
Rectifying Diode (Vf @ maxload)
4.7
μH
Shielded,low ESR, Isat 1A
100
nF
Ceramic, X7R
100
nF
k
k
k
V
Ceramic, X7R
1.2
±1%
5.6
±1%
82
±1%
0.3
Schottky diode
C between Audio input and ASE
100
nF
Ceramic, X7R / X5R
Light Sensor
User defined
TDK BSC2015
www.national.com
34
L
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參數(shù)描述
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LP39542RLX 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Advanced Lighting Management Unit
LP39542RLX/NOPB 功能描述:LED照明驅(qū)動(dòng)器 RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N
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