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參數(shù)資料
| 型號： | SP6648UEB |
| 英文描述： | .15UF 100V 10% MONOLITH CERM CAP |
| 中文描述： | 評估板手冊 |
| 文件頁數(shù)： | 3/5頁 |
| 文件大?。?/td> | 98K |
| 代理商： | SP6648UEB |
5) Using the R
lim
Function
The peak inductor current,
I
PEAK
, is programmed externally by the
R
LIM
resistor connected
between the RLIM pin and GND. The peak inductor current is defined by:
I
PEAK
= 1400/R
LIM
The SP6648 datasheet specifications for R
LIM
give a range of 1.87K to 4K ohms. Using the I
PEAK
equation above gives an I
PEAK
range of 350 to 750mA
.
The saturation current specified for the inductor needs to be greater then the peak current to
avoid saturating the inductor, which would result in a loss in efficiency and could damage the
inductor. The SP6648 evaluation board uses a R
lim
value of 1.87K for an I
peak
= 750mA to allow
the circuit to deliver up to 180mA for 1.3V input and 400mA for 2.6V input. Other values could
be selected using the above relationships.
6) Using the LBON - Low Battery Output Function
The SP6648 will regulate the output current until the input battery is completely discharged. To
provide an early low battery warning, the Low Battery Output function of the SP6648 switching
regulator can be used. LBON is programmed externally by the
R
1
and R
2
resistor divider
connected between VIN, the LBI input pin and GND. When the LBI comparator falling threshold
of 0.61V is reached, D1 switches on, indicating low battery condition. Low battery detect trip
point can be calculated by the following formula:
R
R
61
.
V
=
2
2
1
LOWBAT
R
+
The SP6648 evaluation board R
1
& R
2
resistors have been set to trip for a falling battery
threshold of about 2.0V. Using this relationship, other low battery threshold values can be set
by the user.
7) Brightness Control
One approach to control LED brightness is to apply a PWM signal to the SHDN input of the
SP6648. In this case, the output current will be equal to the product of 350mA and the average
duty cycle at the SHDN pin. An additional 10K potentiometer (R
5
) may also be used for dimming
LED. LED current is varied by the potentiometer between almost zero and full 350mA.
POWER SUPPLY DATA
For the standard evaluation board, The efficiency curve is shown in the figure below.
60
65
70
75
80
85
90
95
100
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
Battery Voltage (V)
E
Fig.3 Efficiency curve of the SP6648LED evaluation board
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP6649 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Ultra-low Quiescent Current, High Efficiency Boost DC-DC Regulator |
| SP6649EU | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Ultra-low Quiescent Current, High Efficiency Boost DC-DC Regulator |
| SP6649EU/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Ultra-low Quiescent Current, High Efficiency Boost DC-DC Regulator |
| SP664P7FC9086 | 制造商:Thomas & Betts 功能描述:Flush Service Floor Boxes |
| SP6650 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:High Efficiency 600mA Synchronous Buck Regulator Ideal for portable designs powered with Li Ion battery |
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