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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)： | 9/12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
9
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
2006 MPS. All Rights Reserved.
Calculate the required inductance value by the
equation:
(
V
IN
×
)
I
f
V
V
V
L
SW
OUT
IN
OUT
×
×
=
Where
I is the peak-to-peak inductor ripple
current. It is recommended to choose
I to be
30%~40% of the maximum load current.
Compensation
The system stability is controlled through the
COMP pin. COMP is the output of the internal
transconductance error amplifier. A series
capacitor-resistor combination sets a pole-zero
combination to control the characteristics of the
control system.
The DC loop gain is:
LOAD
CS
VEA
OUT
V
FB
VDC
R
G
A
V
A
×
×
×
=
Where V
FB
is the feedback voltage, 0.9V, A
VEA
is the transconductance error amplifier voltage
gain, 400 V/V and G
CS
is the current sense
transconductance, (roughly the output current
divided by the voltage at COMP), 4.5A/V.
R
LOAD
is the load resistance:
OUT
OUT
V
LOAD
I
R
=
Where I
OUT
is the output load current.
The system has 2 poles of importance, one is
due to the compensation capacitor (C3), and
the other is due to the load resistance and the
output capacitor (C2), where:
3
C
A
2
G
f
VEA
EA
1
P
×
×
π
=
P1 is the first pole, and G
EA
is the error amplifier
transconductance (450μA/V) and
2
C
R
2
1
f
LOAD
2
P
×
×
π
=
The system has one zero of importance, due to
the compensation capacitor (C3) and the
compensation resistor (R3). The zero is:
3
C
3
R
2
1
f
1
Z
×
×
π
=
If large value capacitors with relatively high
equivalent-series-resistance (ESR) are used,
the zero due to the capacitance and ESR of the
output capacitor can be compensated by a third
pole set by R3 and C4. The pole is:
4
C
3
R
2
1
f
3
P
×
×
π
=
The system crossover frequency (the frequency
where the loop gain drops to 1dB or 0dB) is
important. Set the crossover frequency below
one tenth of the switching frequency to insure
stable operation. Lower crossover frequencies
result in slower response and worse transient
load recovery. Higher crossover frequencies
degrade the phase and/or gain margins and
can result in instability.
Table 1—Compensation Values for Typical
Output Voltage/Capacitor Combinations
V
OUT
C2
R3
C3
C4
1.8V 22μF Ceramic
2.5V 22μF Ceramic
3.3V 22μF Ceramic
47μF Tantalum
(300m
)
47μF Tantalum
(300m
)
47μF Tantalum
(300m
)
6.8k
9.1k
12k
3.3nF
2.2nF
1.8nF
None
None
None
1.8V
13k
2nF
1nF
2.5V
18k
1.2nF 750pF
3.3V
24k
1nF
560pF
Choosing the Compensation Components
The values of the compensation components
listed in Table 1 yields a stable control loop for
the given output voltage and capacitor. To
optimize the compensation components for
conditions not listed in Table 1, use the
following procedure.
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|---|---|
| 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(kāi)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(kāi)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(kāi)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(kāi)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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