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參數(shù)資料
| 型號(hào)： | SP6682UEB |
| 英文描述： | Evaluation Board Manual |
| 中文描述： | 評(píng)估板手冊(cè) |
| 文件頁(yè)數(shù)： | 7/12頁(yè) |
| 文件大?。?/td> | 190K |
| 代理商： | SP6682UEB |
7
Date: 5/5/04
SP6682 High Efficiency Charge Pump Regulator for White LEDs Copyright 2004 Sipex Corporation
In this application, the bias resistor can be se-
lected by:
R
B
= V
FB
I
LED (TOTAL)
where I
LED(TOTAL)
is the total operating current
of all the white LEDs.
To use SP6682 as a voltage source for fixed
voltage applications, a voltage divider is need to
program the ouput voltage, as shown in figure 12.
The output voltage is set by the ratio of the two
Anode
5
8
SP6682
Cathode
V
OUT
R6
1
R5
2.2uF
V
FB
2-wire W-LED
module
GND
Figure 12. Driving 2-wire white LED module as voltage
source
resistors and the feedback control voltage as
shown by:
V
OUT
= R
5
) V
FB
6
Programming the Operating Mode
SP6682 can automatically change from X1.5
mode to X2 mode for highest efficiency. To use
this feature, divider resistors should be chosen
according to the specific application, as shown
in figure 13.
The guideline for divider resistor selections is as
follows. For high input voltage, the SP6682 will
work in X1.5 mode. When the input voltage
drops to Vth threshold voltage, it will switch to
X2 mode automatically. The Vth threshold volt-
age for mode change can be calculated by:
V
TH
= (V
F
+ 0.306 + m I
LED
R
OUT
)/1.5
Where V
F
and m are the forward voltage and
number of the white LEDs, Rout is the output
resistance of the SP6682.
The equation for the voltage divider R
1
and R
2
with V
MODE
= 1.25V is:
V
TH
= 1.25V (1+R
1
/R
2
)
which can be expressed as R1:
R
1
= (V
TH
/ 1.25 -1) R
2
For the typical SP6682 application, Using
V
F
=3.6V, m=4, I
LED
=15mA, R
OUT
=16
, the
V
TH
will be 3.24V. Select R
2
=100k
, then
R
1
=158k
.
Capacitor Selection
Ceramic capacitors are recommended for their
inherently low ESR, which will help produce
low peak to peak output ripple, and reduce high
frequency spikes.
The fly capacitor controls the strength of the
charge pump. Selection of the fly capacitor is a
trade-off between the output voltage ripple and
the output current capability. Decreasing the fly
capacitor will reduce the output voltage ripple
because less charge will be delivered to the
output capacitor. However, smaller fly capaci-
V
IN
V
IN
C2
GND
4
V
MODE
R1
SP6682
8
R2
3
Figure 13. Programming the Vmode Resistors
APPLICATION INFORMATION: Continued
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PDF描述 |
|---|---|
| SP6683 | High Power LED Driver for Parallel Configuration |
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| SP6683EU | High Power LED Driver for Parallel Configuration |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP6683 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:High Power LED Driver for Parallel Configuration |
| SP6683EB | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP6683ER | 制造商:Exar Corporation 功能描述:Driver, Other |
| SP6683ER/TR | 功能描述:LED照明驅(qū)動(dòng)器 High Power Parallel Configuration 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 |
| SP6683ER-L | 功能描述:LED照明驅(qū)動(dòng)器 Configuration 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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