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參數(shù)資料
| 型號： | MAX1800 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Digital Camera Step-Up Power Supply |
| 中文描述： | 數(shù)碼相機(jī)升壓型電源 |
| 文件頁數(shù)： | 21/24頁 |
| 文件大?。?/td> | 461K |
| 代理商： | MAX1800 |
Choose the MOSFET for low dropout. The maximum
acceptable on-resistance of the MOSFET is determined
by the maximum load current to achieve the required
dropout voltage (minimum input voltage minus output
voltage):
Determine the minimum output capacitance as follows.
The output capacitor and load resistance set the domi-
nant pole (f
P1
):
The second pole (f
P2
) occurs due to the AO output
resistance and the gate capacitance of the external
MOSFET:
where R
AO
is the output resistance of the gain block at
AO, and C
(GATE-Q1)
is the total gate capacitance of the
MOSFET, Q1. The control loop DC gain is:
where A
V-GB
is the voltage gain from AI to AO (typically
100), and G
(FS-Q1)
is the forward transconductance
gain of Q1. Choose the output capacitance so that the
second pole occurs at or above the loop-gain crossover
frequency:
Since V
REF
is 1.25V, A
(V-GB)
is typically 100, and R
AO
is typically 800
, then:
Using the Linear Regulator to Make a
Step-Up/Step-Down Circuit
Some applications have a battery voltage that can be
either greater than or less than the desired output volt-
age. In this case, a step-up or step-down converter will
not be able to generate the required output voltage
under all conditions. To avoid this limitation, use a step-
C
G
C
)
V
OUT
FS Q
(
GATE Q
OUT
≥
(
)
,
12 500
1
1
C
V
V
A
G
)
R
)
C
OUT
REF
OUT
V GB
FS Q
(
AO
GATE Q
≥
(
(
)
1
1
A
V
V
A
G
)
R
VLOOP
REF
OUT
V GB
FS Q
(
LOAD
=
(
)
1
f
R
C
P
AO
GATE Q
(
2
1
1
2
)
=
π
f
R
C
P
LOAD
OUT
1
1
2
=
π
R
DS ON
≤
V
I
DROPOUT
LOAD(MAX)
R
R
V
V
OUT
REF
1
2
1
=
M
Digital Camera Step-Up
Power Supply
______________________________________________________________________________________
21
Figure 11. Linear Regulator
C
OUT
Q
1
V
REF
R
1
R
2
LOAD
RESISTOR
(R
L
)
INPUT VOLTAGE
(FROM MAIN
OUTPUT)
PART OF MAX 1800
ONA
AI
AI
ON
OFF
Q
1
C
1
C
2
C
3
D
1
D
2
D
3
C
C
R
1
V
OUT+
V
OUT-
L
R
2
R
C
MAIN
IN
COMP
DCON
PART OF
MAX1800
DL
FB
INPUT
1-CELL
LITHIUM-ION
Figure 10. Auxiliary Charge-Pump Configuration
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| MAX1806EUA | 3A Fixed Low Dropout Linear Regulator (LDO) |
| MAX1806EUA08 | 3A Fixed Low Dropout Linear Regulator (LDO) |
| MAX1806EUA15 | 3A Fixed Low Dropout Linear Regulator (LDO) |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1800EHJ | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| MAX1800EHJ-T | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| MAX1800EVKIT | 功能描述:電源管理IC開發(fā)工具 RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| MAX1801EKA | 制造商:Maxim Integrated Products 功能描述:DIGITAL CAMERA STEP-UP SLAVE DC-DC - Rail/Tube |
| MAX1801EKA+ | 制造商:Maxim Integrated Products 功能描述:DC DC CNTRLR SGL-OUT STEP UP 2.7V TO 5.5V 8PIN SOT-23 - Rail/Tube |
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