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參數(shù)資料
| 型號： | MAX1901 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | SWITCH, 3 POS DIP |
| 中文描述： | 500kHz、多路輸出、低噪聲、電源控制器，用于筆記本電腦 |
| 文件頁數(shù)： | 20/33頁 |
| 文件大?。?/td> | 649K |
| 代理商： | MAX1901 |
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M
500kHz Multi-Output, Low-Noise Power-Supply
Controllers for Notebook Computers
20
______________________________________________________________________________________
tor (primary) current, pulling current from the output fil-
ter capacitor and causing the flyback transformer to
operate in forward mode. The low impedance present-
ed by the transformer secondary in forward mode
dumps current into the secondary output, charging up
the secondary capacitor and bringing V
DD
or SECFB
back into regulation. The secondary feedback loop
does not improve secondary output accuracy in normal
flyback mode, where the main (primary) output is heavi-
ly loaded. In this condition, secondary output accuracy
is determined by the secondary rectifier drop, trans-
former turns ratio, and accuracy of the main output volt-
age. A linear post-regulator may still be needed to meet
strict output-accuracy specifications.
MAX1902 has a V
DD
pin that regulates at a fixed 13.5V,
set by an internal resistor-divider. The MAX1901/
MAX1904 have an adjustable secondary-output voltage
set by an external resistor-divider on SECFB (Figure 5).
Ordinarily, the secondary regulation point is set 5% to
10% below the voltage normally produced by the flyback
effect. For example, if the output voltage as determined
by turns ratio is 15V, set the feedback resistor ratio to pro-
duce 13.5V. Otherwise, the SECFB one-shot might be
triggered unintentionally, unnecessarily increasing supply
current and output noise.
12V Linear Regulator Output (MAX1902)
The MAX1902 includes a 12V linear regulator output
capable of delivering 120mA of output current.
Typically, greater current is available at the expense of
output accuracy. If an accurate output of more than
120mA is needed, an external pass transistor can be
added. The circuit in Figure 6 delivers more than
200mA. Total output current is constrained by the V+
input voltage and the transformer primary load (see
Maximum V
DD
Output Current vs. Input Voltage graphs
in the
Typical Operating Characteristics
).
Design Procedure
The three predesigned 3V/5V standard application cir-
cuits (Figure 1 and Table 1) contain ready-to-use solu-
tions for common application needs. Also, one
standard flyback transformer circuit supports the
12OUT linear regulator in the
Applications Information
section. Use the following design procedure to optimize
these basic schematics for different voltage or current
requirements. But before beginning a design, firmly
establish the following:
Maximum Input (Battery) Voltage, V
IN(MAX)
. This value
should include the worst-case conditions, such as no-
load operation when a battery charger or AC adapter is
MAX1901
MAX1904
POSITIVE
SECONDARY
OUTPUT
MAIN
OUTPUT
DH_
V+
SECFB
2.5V REF
R2
R1
1-SHOT
TRIG
DL_
WHERE V
REF
(NOMINAL) = 2.5V
+V
TRIP
= V
REF
(
1 + R1
)
R2
MAX1902
V
DD
OUTPUT
12V OUTPUT
200mA
MAIN
OUTPUT
2N3906
0.1
μ
F
0.1
μ
F
0.1
μ
F
2.2
μ
F
10
μ
F
10
V+
V
DD
12OUT
DH_
DL_
Figure 5. Adjusting the Secondary Output Voltage with SECFB
Figure 6. Increased 12V Linear Regulator Output Current
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX1901-MAX1904 | 3 POSITION RIGHT ANGLE DIP SWITCH |
| MAX1901EAI | 500kHz Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers |
| MAX1901ETJ | 500kHz Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers |
| MAX1902 | 500kHz Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers |
| MAX1902EAI | 500kHz Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1901EAI | 功能描述:DC/DC 開關(guān)控制器 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 安裝風格: 封裝 / 箱體:CPAK |
| MAX1901EAI+ | 功能描述:DC/DC 開關(guān)控制器 500kHz Multi-Output Power-Supply Ctlr 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 安裝風格: 封裝 / 箱體:CPAK |
| MAX1901EAI+T | 功能描述:DC/DC 開關(guān)控制器 500kHz Multi-Output Power-Supply Ctlr 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 安裝風格: 封裝 / 箱體:CPAK |
| MAX1901EAI-T | 功能描述:DC/DC 開關(guān)控制器 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 安裝風格: 封裝 / 箱體:CPAK |
| MAX1901ETJ | 功能描述:DC/DC 開關(guān)控制器 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 安裝風格: 封裝 / 箱體:CPAK |
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