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參數(shù)資料
| 型號(hào)： | MP2108 |
| 廠商： | Monolithic Power Systems, Inc. |
| 英文描述： | 2A, 6V, 740KHz Synchronous Buck Converter |
| 中文描述： | 第2A，6V的，740KHz同步降壓轉(zhuǎn)換器 |
| 文件頁(yè)數(shù)： | 8/12頁(yè) |
| 文件大小： | 311K |
| 代理商： | MP2108 |
MP2108 – 2A, 6V, 740KHz SYNCHRONOUS BUCK CONVERTER
MP2108 Rev 1.1
10/2/2006
www.MonolithicPower.com
8
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
2006 MPS. All Rights Reserved.
rate as the voltage at SS, forcing a linear
output voltage ramp from 0V to the desired
regulation voltage during soft-start.
The soft-start period is determined by the
equation:
5
C
45
.
t
SS
×
=
Where C5
(in nF) is the soft-start capacitor from
SS to GND, and t
SS
(in ms) is the soft-start
period. Determine the capacitor required for a
given soft-start period by the equation:
SS
t
22
.
5
C
×
=
Use values for C5 between 10nF and 22nF to
set the soft-start period between 4ms and
10ms.
Setting the Output Voltage (see Figure 2)
Set the output voltage by selecting the resistive
voltage divider ratio. The voltage divider drops
the output voltage to the 0.9V feedback voltage.
Use 10k
for the low-side resistor of the
voltage divider. Determine the high-side resistor
by the equation:
1
R
1
V
9
V
2
R
OUT
×
=
Where R2 is the high-side resistor, R1 is the
low-side resistor and V
OUT
is the output voltage.
Selecting the Input Capacitor
The input current to the step-down converter is
discontinuous, so a capacitor is required to
supply the AC current to the step-down
converter while maintaining the DC input
voltage. A low ESR capacitor is required to
keep the noise at the IC to a minimum. Ceramic
capacitors are preferred, but tantalum or low
ESR electrolytic capacitors are also an option.
The capacitor can be electrolytic, tantalum or
ceramic. Because it absorbs the input switching
current, it must have an adequate ripple current
rating. Use a capacitor with RMS current rating
greater than 1/2 of the DC load current.
For stable operation, place the input capacitor
as close to the IC as possible. A smaller high
quality 0.1μF ceramic capacitor may be placed
closer to the IC with the larger capacitor placed
further away.
If using this technique, it is recommended that
the larger capacitor be a tantalum or electrolytic
type. All ceramic capacitors should be placed
close to the IC. For most applications, a 10
μ
F
ceramic capacitor will work.
Selecting the Output Capacitor
The output capacitor (C2) is required to
maintain the DC output voltage. Low ESR
capacitors are preferred to keep the output
voltage ripple to a minimum. The characteristics
of the output capacitor also affect the stability of
the
regulation
control
tantalum, or low ESR electrolytic capacitors are
recommended.
system.
Ceramic,
The output voltage ripple is:
×
×
+
×
×
×
=
2
C
f
8
1
R
V
V
1
L
f
V
V
SW
ESR
IN
OUT
SW
OUT
RIPPLE
Where V
RIPPLE
is the output voltage ripple, f
SW
is
the switching frequency, V
IN
is the input voltage
and R
ESR
is the equivalent series resistance of
the output capacitors.
Choose an output capacitor to satisfy the output
ripple requirements of the design. A 22μF
ceramic
capacitor
is
applications.
suitable
for
most
Selecting the Inductor
The inductor is required to supply constant
current to the output load while being driven by
the switched input voltage. A larger value
inductor results in less ripple current that in turn
results in lower output ripple voltage. However,
the larger value inductor is likely to have a
larger
physical
size
resistance. Choose an inductor that does not
saturate under the worst-case load conditions.
A good rule for determining the inductance is to
allow peak-to-peak ripple current to be
approximately 30% to 40% of the maximum
load current. Make sure that the peak inductor
current (the load current plus half the peak-to-
peak inductor ripple current) is below 2.5A to
prevent loss of regulation due to the current
limit.
and
higher
series
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| MP2108_06 | 2A, 6V, 740KHz Synchronous Buck Converter |
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| MP2109 | Dual 1.2MHz, 800mA Synchronous Step-Down Converter |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MP2108_06 | 制造商:MPS 制造商全稱:Monolithic Power Systems 功能描述:2A, 6V, 740KHz Synchronous Buck Converter |
| MP2108DK | 制造商:MPS 制造商全稱:Monolithic Power Systems 功能描述:2A, 6V, 740KHz Synchronous Buck Converter |
| MP2108DK-LF-P | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 2A, 6V, 720kHz Synchronous Buck RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| MP2108DK-LF-Z | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 2A, 6V, 720kHz Synchronous Buck RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| MP2108DQ | 制造商:MPS 制造商全稱:Monolithic Power Systems 功能描述:2A, 6V, 740KHz Synchronous Buck Converter |
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