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参数资料
| 型号： | SP6655EB |
| 厂商： | Exar Corporation |
| 文件页数： | 14/17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
supply. The typical input capacitor for the
SP6655 is 10μF ceramic. These capacitors will
provide good high frequency bypassing and
their low ESR will reduce resistive losses for
higher efficiency. An RC filter is recommended
for the V IN pin 2 to effectively reduce the noise
for the IC's analog supply rail which provides
power to sensitive circuits. This time constant
needs to be at least 5 times greater than the
switching period, which is calculated as 1/FLP
during the CCM mode. The typical application
schematic uses the values of R VIN = 10Ω and
C VIN = 1 μF to meet these requirements.
O UTPUT V OLTAGE P ROGRAM
The output voltage is programmed by the
external divider, as shown in the typical
application circuit on page 1. First pick a value
for R I that is no larger than 300KΩ. Too large a
value of R I will reduce the AC voltage seen by
the loop comparator, since the internal FB pin
capacitance can form a low pass filter with R F
in parallel with R I . The formula for R F with a
given R I and output voltage is:
O UTPUT V OLTAGE R IPPLE F REQUENCY
An important consideration in a power supply
application is the frequency value of the
output ripple. Given the control technique of
the SP6655 (as described in the operations
section), the frequency of the output ripple will
vary when in light to moderate load in the
discontinuous or PFM mode. For moderate to
heavy loads greater than about 100mA
inductor current ripple, (for the typical 10μH
inductor application on 100mA is half the
200mA inductor current ripple), the output
ripple frequency will be fairly constant. From
the operations section, this maximum loop
frequency in continuous conduction mode is:
Data for loop frequency, as measured from
output voltage ripple frequency, can be found
in the typical performance curves.
L AYOUT C ONSIDERATIONS
Proper layout of the power and control circuits
is necessary in a switching power supply to
obtain good output regulation with stability
and a minimum of output noise. The SP6655
application circuit can be made very small and
reside close to the IC for best performance
and solution size, as long as some layout
techniques are taken into consideration. To
avoid excessive interference between the
SP6655 high frequency converter and the
other active components on the board, some
rules should be followed. Refer to the typical
application schematic on page 1 and the
sample PCB layout shown in the following
figures to illustrate how to layout a SP6655
power supply.
Avoid injecting noise into the sensitive part of
circuit via the ground plane. Input and output
capacitors conduct high frequency current
through the ground plane. Separate the
control and power grounds and connect them
together at a single point. Power ground plane
is shown in the figure titled PCB top sample
layout and connects the ground of the C OUT
capacitor to the ground of the C IN capacitor
and then to the PGND pin 10. The control
ground plane connects from pin 9 GND to
ground of the C VIN capacitor and the R I ground
return of the feedback resistor. These two
separate control and power ground planes
come together in the figure titled PCB top
sample layout where SP6655 pin 9 GND is
connected to pin 10 PGND.
Power loops on the input and output of the
converter should be laid out with the shortest
and widest traces possible. The longer and
narrower the trace, the higher the resistance
and inductance it will have. The length of
traces in series with the capacitors increases
their ESR and ESL and reduces their
effectiveness at high frequencies. Therefore,
put the 1μF bypass capacitor as close to the
V IN and GND pins of the converter as possible,
the 10μF C IN close to the P VIN pin and the 10μF
output capacitor as close to the inductor as
possible. The external voltage feedback
network R F , R I and feedforward capacitor C F
should be placed very close to the FB pin. Any
noise traces like the LX pin should be kept
? 2012 Exar Corporation
14/17
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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