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参数资料
| 型号： | SP6648EB |
| 厂商： | Exar Corporation |
| 文件页数： | 12/16页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR SP6648 |
| 标准包装： | 1 |
| 系列： | * |
APPLICATIONS INFORMATION
SP6648LEDEB Evaluation Board with
LumiLED High Brightness White LED
For the high brightness LumiLED white LED
application, the SP6648 is generally programmed
as a current source. The bias resistor R b is used
to set the operating current of the white LED in
the equation:
R b = V REF /I F
where V REF is around 0.61V, I F is the operating
current of the LumiLED. To set the operating
current to be about 350mA, R b is selected as 1.8 Ω
as shown in the following schematic. The effi-
ciency of the SP6648 LumiLED circuit is im-
proved by the use of a silicon diode D1 and
resistor R 1 to set the voltage at the current sense
resistor R 2 to 0.61V instead of the higher 1.25V
at the FB pin. An efficiency curve follows
showing the SP6648 efficiency driving 350mA
output current into the high brightness LumiLED.
V BATT
1.8-3.2V
L1 10μH
Important:
1μF Ceramic Cap at V OUT Pin
R 1
C1
10μF
1
2
3
4
V BATT
LBI
LBON
R LIM
V OUT
SP6648 LX
P GND
GND
10
9
8
7
needed for stable regulation
C4
1μF
16.2k
C2
10μF
D2
1W LED
350mA
5
SHDN
FB
6
R 5 10K
D1 1N4148
V REF = 0.61V
R LIM
1.87K
(R 5 optional)
Rb
1.8?
I OUT =0.61V/R b
SP6648LEDEB Evaluation Board Schematic
100
95
90
85
80
75
70
65
As shown in following scope photos, if the
SP6648 is powered up before the LumiLED is
plugged in, the circuit will bring the Feedback
pin to 0.0V and the SP6648 has a feature to set
the output voltage to be 3.3V. Once the LumiLED
is plugged in, the Feedback pin will go up to
1.25V and begin to regulate. The output voltage
will go from 3.3V to 3.68V (=V F +0.61V), where
V F is the forward voltage of the LumiLED.
When the LumiLED is open, the Feedback pin
60
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
voltage will go to 0.0V and the output voltage
will go to 3.3V which will protect the part.
Battery Voltage (V)
SP6648LEDEB Efficiency Curve
Date: 6/7/06 Rev B
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
12
? 2006 Sipex Corporation
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP6648ER | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Ultra-low Quiescent Current, High Efficiency Boost Regulator |
| SP6648ER/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Ultra-low Quiescent Current, High Efficiency Boost Regulator |
| SP6648ER-L | 功能描述:DC/DC 开关控制器 Efficiency Boost Regulator RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| SP6648ER-L/TR | 功能描述:DC/DC 开关控制器 Ultra-low Quiescent High Efficiency RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| SP6648EU | 制造商:Rochester Electronics LLC 功能描述: 制造商:Exar Corporation 功能描述: |
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