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| 型号： | SP6648LEDEB |
| 厂商： | Exar Corporation |
| 文件页数： | 11/16页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR SP6648LED |
| 标准包装： | 1 |
| 系列： | * |
APPLICATIONS INFORMATION : Continued
V OUT Programming
The SP6648 can be programmed as either a
voltage source or a current source. To program
the SP6648 as a voltage source, the SP6648
requires 2 feedback resistors R1 & R2, as shown
in the SP6648EB evaluation board schematic, to
control the output voltage. To set V OUT in the
voltage mode, use the equation:
R1 = [(V OUT /1.25)-1] * R2
Using the R LIM Function
The peak inductor current, I PEAK , is programmed
externally by the R LIM resistor connected be-
tween the R LIM pin and GND. The peak inductor
current is defined by:
I PEAK = 1600/R LIM
The saturation current specified for the inductor
needs to be greater than the peak current to avoid
saturating the inductor, which would result in a
loss in efficiency and could damage the induc-
tor. The SP6648 evaluation board uses a R LIM
value of 1.87K for an I PEAK = 850mA 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.
Using the LBON - Low Battery Output
Function
The SP6648 will regulate the output until the
input battery is completely discharged or until
the under voltage lock-out (UVLO) occurs at
V BATT = 0.61V. To provide a low battery warn-
ing, the Low Battery Output function of the
SP6648 can be used. LBON is programmed
externally by the R 3 and R 4 resistor divider
connected between V BATT , the LBI input pin
and GND. The LBON is an open drain output,
which is active low and is pulled up by a 1M Ω
resistor R 5 to V OUT . When the LBI comparator
falling threshold of 0.61V is reached, the LBON
output goes low as determined by the relation-
ship:
V LOWBATT = 0.61 * [(R 3 + R 4 )/R 4 ]
The SP6648 evaluation board R 3 & R 4 resistors
have been set to trip for a falling battery thresh-
old of about 2.0V. Using this relationship, other
low battery threshold values can be set by the
user.
UVLO the Under Voltage Lock-Out Function
Once started up, the SP6648 will regulate the
output until the input battery is completely dis-
charged or until the under voltage lock-out
(UVLO) occurs at V BATT = 0.61V. The UVLO
function will completely open all switches until
the battery again rises above the 0.61V thresh-
old.
Maximum Startup Current
It should be noted that for low input voltages the
SP6648 startup circuit cannot support large load
currents at startup. In startup the SP6648 needs
to boost the output from zero volts using the
input voltage. Once the output is greater than
1.9V, the operating circuit takes over and the
SP6648 can supply much more current. Curves
of maximum load current in startup for the
SP6648 are shown in the typical performance
characteristics and can be compared with the
page one curve for maximum load current in
operation.
For 1-cell battery applications, it is recommended
to apply any large load current after the SP6648
has started up, typically in a few milliseconds.
This is typically not a problem in many applica-
tions where the load is a processor whose load
current is low until the processor voltage comes
up.
Date: 6/7/06 Rev B
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
11
? 2006 Sipex Corporation
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP6648UEB | 功能描述:电源管理IC开发工具 Ultra Low Quies Cur Hi-Eff Boost Reg RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| SP6649 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Ultra-low Quiescent Current, High Efficiency Boost DC-DC Regulator |
| SP6649EU | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Ultra-low Quiescent Current, High Efficiency Boost DC-DC Regulator |
| SP6649EU/TR | 制造商:SIPEX 制造商全称: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 |
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