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参数资料
| 型号： | SP6655EB |
| 厂商： | Exar Corporation |
| 文件页数： | 12/17页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR SP6655 |
| 标准包装： | 1 |
| 系列： | * |
S P 6 6 5 5
H i g h E f f i c i e n c y 4 0 0 m A S y n c h r o n o u s B u c k R e g u l a t o r
currents on supply pins 1 and 2. After pins 4
or 5 are brought high to enable the converter,
there is a turn on delay to allow the regulator
logic level battery low indicator. A low
bandwidth comparator and 3% hysteresis filter
the input voltage ripple to prevent noisy
circuitry to re-establish
itself.
Power
transitions at the threshold. BLON is forced
conversion begins with the assertion of the
internal reference ready signal which occurs
approximately 150μs after the enable signal is
received.
B ATTERY L OW I NDICATOR
The BLON function is a differential
measurement of (V IN -V OUT ) which causes the
open drain NMOS on pin 3 to sink current to
ground when (V IN -V OUT ) < 300mV. Tying a
resistor from pin 3 to V IN or V OUT creates a
APPLICATION INFORMATION
I NDUCTOR S ELECTION
The SP6655 uses a specially adapted minimum
on-time control of regulation utilizing a
precision comparator and bandgap reference.
This adaptive minimum on-time control has
the advantage of setting a constant current
ripple for a given inductor size. From the
operations section it has been shown:
Inductor Current Ripple, I LR ≈ K ON / L
For the typical SP6655 application circuit with
inductor size of 10μH, and K ON of 2V*μsec, the
SP6655 current ripple would be about 200mA,
and would be fairly constant for different input
and output voltages, simplifying the selection
of components for the SP6655 power circuit.
Other inductor values could be selected, as
shown in Table 1 Components Selection. Using
a larger value than 10μH in an attempt to
reduce output voltage ripple would reduce
inductor current ripple and may not produce
as stable an output ripple. For larger inductors
with the SP6655, which has a peak inductor
current of 0.625A, most 15μH or 22μH
inductors would have to be of larger physical
sizes, limiting their use in small portable
applications. Smaller values like 10 μ H would
more easily meet the 0.625A limit and come in
small case sizes, and the increased inductor
current ripple of almost 200mA would produce
very stable regulation and fast load transient
Low when in UVLO.
E XTERNAL F EEDBACK P IN
The FB pin 6 is compared to an internal
reference voltage of 0.8V to regulate the
SP6655 output. The output voltage can be
externally programmed within the range
+1.0V to +5.0V by tying a resistor from FB to
ground and FB to V OUT (pin7). See the
applications section for resistor selection
information.
response at the expense of slightly reduced
efficiency.
Other inductor parameters are important, such
as the inductor current rating and the DC
resistance. When the current through the
inductor reaches the level of I SAT , the
inductance drops to 70% of the nominal value.
This non-linear change can cause stability
problems or excessive fluctuation in inductor
current ripple. To avoid this, the inductor
should be selected with saturation current at
least equal to the maximum output current of
the converter plus half the inductor current
ripple. To provide the best performance in
dynamic conditions such as start-up and load
transients, inductors should be chosen with
saturation current close to the SP6655
inductor current limit of 0.625A.
DC resistance, another important inductor
characteristic, directly affects the efficiency of
the converter, so inductors with minimum DC
resistance should be chosen for high efficiency
designs. Recommended inductors with low DC
resistance are listed in Table 2. Preferred
inductors for on board power supplies with the
SP6655 are magnetically shielded types to
minimize radiated magnetic field emissions.
? 2012 Exar Corporation
12/17
Rev. 1.0.0
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP6655ER | 制造商:Rochester Electronics LLC 功能描述: 制造商:Exar Corporation 功能描述: |
| SP6655ER/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:High Efficiency 400mA Synchronous Buck Regulator Ideal for portable designs powered with Li Ion battery |
| SP6655ER-L | 功能描述:DC/DC 开关控制器 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 |
| SP6655ER-L/TR | 功能描述:DC/DC 开关控制器 High Eff 400mA Synchronous 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 |
| SP6655EU-L | 功能描述:开关变换器、稳压器与控制器 High Eff 400mA Synchronous RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
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