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參數(shù)資料
| 型號(hào)： | SP6690EK |
| 元件分類： | LED驅(qū)動(dòng)器 |
| 英文描述： | Micro Power Boost Regulator Series White LED Driver |
| 中文描述： | 微功率升壓穩(wěn)壓器系列白光LED驅(qū)動(dòng)器 |
| 文件頁數(shù)： | 11/16頁 |
| 文件大?。?/td> | 270K |
| 代理商： | SP6690EK |
11
Date: 05/25/04
SP6690 Micro Power Boost Regualtor, Series White LED Driver Copyright 2004 Sipex Corporation
Layout Consideration
Both the input capacitor and the output capacitor
should be placed as close as possible to the IC.
This can reduce the copper trace resistance
which directly effects the input and output
ripples. The feedback resistor network should
be kept close to the FB pin to minimize copper
trace connections that can inject noise into the
system. The ground connection for the feedback
resistor network should connect directly to the
GND pin or to an analog ground plane that is tied
directly to the GND pin. The inductor and the
schottky diode should be placed as close as
possible to the switch pin to minimize the noise
coupling to the other circuits, especially the
feedback network.
Power Efficiency
For the typical application circuit, the output
efficiency of the circuit is expressed by
η
= V
OUT
I
OUT
V
IN
I
IN
Where V
IN
, I
IN
, V
OUT
, I
OUT
are the input and
output voltage and current respectively.
While the white LED efficiency is expressed by
η
= (V
OUT
- 1.22) I
OUT
V
IN
I
IN
This equation indicates that the white LED
efficiency will be much smaller than the output
efficiency of the circuit when V
OUT
is not very
large, compared to the feedback voltage (1.22V).
The other power is consumed by the bias resis-
tor. To reduce this power loss, two circuits can
be used, as shown in Figure 23 and Figure 24. In
Figure 23, a general-purpose diode (for ex-
ample, 1N4148) is used to bring the voltage
across the bias resistor to be around 0.7V. R
1
is
used to create a loop that provides around 100
μ
A
operating current for the diode. 3% efficiency
improvement can be achieved by using this
APPLICATION INFORMAMTION: Continued
method.
Figure 23. Improve Efficiency with Diode in Feedback
Loop
To further improve the efficiency and reduce the
effects of the ambient temperature on the diode
D1 used in method 1, an op amp circuit can be
used as shown in Figure 24. The gain of the op
amp circuit can be calculated by:
Av = R
1
+ R
2
R
1
If the voltage across the bias resistor is set to be
0.1V the current through R
1
and R
2
to be around
100
μ
A, R
1
and R
2
can be selected as 1K and
11.2K respectively. LMV341 can be used be-
cause of its small supply current, offset voltage
and minimum supply voltage. By using this
method, the efficiency can be increased around
VIN
WLED MODULE
C1
MurL1 10uH 0.45A
DS
MBR0530
D1
DIODE
34.8ohm
Rb
C2
2.2uF
R1
150Kohm
1.22V
2.7-4.2V
0.7V
U1
SP6690
1
2
3
4
5
V
IN
SW
GND
FB
SHDN
LMV341
1
3
4
+
-
OUT
2
6
0.1V
C2
2.2uF
2.7-4.2V
1.22V
Vbattery
U1
SP6690
1
SW
2
3
4
5
V
IN
GND
FB
SHDN
5
DS
MBR0530
R1
1K
WLED MODULE
C1
R2
11.2K
Vbattery
MurL1 10uH 0.45A
Rb
5.1
7%.
Figure 24. Improve Efficiency with Op Amp in Feedback
Loop
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SP6690ER | Micro Power Boost Regulator Series White LED Driver |
| SP6690EU | Evaluation Board Manual |
| SP6690EK1 | CAP CERM .5PF 25V NP0 0201 |
| SP6691 | Micro Power Boost Regulator Series White LED Driver |
| SP674AA | 12-Bit Sampling A/D Converters |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP6690EK/TR | 制造商:Exar Corporation 功能描述:Driver, Other |
| SP6690EK1 | 制造商:Exar Corporation 功能描述:Driver, Other |
| SP6690EK1/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Micro Power Boost Regulator Series White LED Driver |
| SP6690EK-L | 制造商:Exar Corporation 功能描述:BOOST REG WHITE LED DRIVE 6690 |
| SP6690EK-L/TR | 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
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