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參數(shù)資料
| 型號(hào)： | SP6656ER |
| 英文描述： | High Efficiency 400mA Synchronous Buck Regulator with Bit Programmable Output |
| 中文描述： | 高效率400mA同步降壓穩(wěn)壓器的可編程輸出位 |
| 文件頁數(shù)： | 12/17頁 |
| 文件大?。?/td> | 185K |
| 代理商： | SP6656ER |
12
Date: 7/9/04
SP6656 High Efficiency 400mA Synchronous Buck Regulator with Bit Programmable Output Copyright 2004 Sipex Corporation
For the 10
μ
F Ceramic Output Capacitor with
0.003
ESR, and a 10
μ
H inductor yielding 200mA
inductor current ripple I
LR
, the V
OUT
ripple would
be 0.6mVpp. Since 0.6mV is a very small signal
level, the actual value would probably be as large
as 10mV due to noise and layout issues, but this
illustrates that the SP6656 output ripple can be
very low indeed. To improve stability, a small
ceramic capacitor, C
F
= 22pF should be paralleled
with the feedback voltage divider RF, as shown on
the typical application schematic on page 1. An-
other function of the output capacitance is to hold
up the output voltage during the load transients and
prevent excessive overshoot and undershoot. The
typical performance characteristics curves show
very good load step transient response for the
SP6656 with the recommended output capaci-
tance of 10
μ
F ceramic.
The input capacitor will reduce the peak current
drawn from the battery, improve efficiency and
significantly reduce high frequency noises in-
duced by a switching power supply. The typical
input capacitor for the SP6656 is 10
μ
F ceramic.
These capacitors will provide good high frequency
bypassing and their low ESR will reduce resistive
losses for higher efficiency. An RC filter is recom-
mended for the V
IN
pin 2 to effectively reduce the
noise for the ICs analog supply rail which powers
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
= 10
and C
VIN
= 1
μ
F to meet these
requirements.
APPLICATION INFORMATION
inductor current ripple of almost 200mA would
produce very stable regulation and fast load
transient response at the expense of slightly
reduced efficiency.
Other inductor parameters are important: the in-
ductor 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 in-
ductor current ripple. To avoid this, the inductor
should be selected with saturation current at least
equal to the maximum output current of the con-
verter plus half the inductor current ripple. To
provide the best performance in dynamic condi-
tions such as start-up and load transients, inductors
should be chosen with saturation current close to
the SP6656 inductor current limit of 0.625A.
DC resistance, another important inductor charac-
teristic, directly affects the efficiency of the con-
verter, 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 SP6656 are mag-
netically shielded types to minimize radiated mag-
netic field emissions.
Capacitor Selection
The SP6656 has been designed to work uith very
low ESR output capacitors (listed in Table 2
Component Selection) which for the typical appli-
cation circuit are 10
μ
F ceramic capacitors. These
capacitors combine small size, low ESR and good
value. To regulate the output with low ESR capaci-
tors of 0.01
or less, an internal ramp voltage
V
RAMP
has been added to the FB signal to reliably
trip the loop comparator (as described in the Op-
erations section).
Output ripple for a buck regulator is determined
mostly by output capacitor ESR, which for the
SP6656 with a constant inductor current ripple can
be expressed as:
V
OUT
(ripple) = I
LR
* R
ESR
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| SP6656 | High Efficiency 400mA Synchronous Buck Regulator with Bit Programmable Output |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP6656ER/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:High Efficiency 400mA Synchronous Buck Regulator with Bit Programmable Output |
| SP6656ER3 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:High Efficiency 400mA Synchronous Buck Regulator with Dynamically Adjustable Voltage Output |
| SP6656ER3-L | 功能描述:DC/DC 開關(guān)控制器 High Eff. 400mA Sync. Buck Reg RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| SP6656ER3-L/TR | 功能描述:DC/DC 開關(guān)控制器 High Eff 400mA Synchronous RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| SP6656ER3TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:High Efficiency 400mA Synchronous Buck Regulator with Dynamically Adjustable Voltage Output |
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