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參數(shù)資料
| 型號(hào)： | MAX1880EUG |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Quad-Output TFT LCD DC-DC Converters with Buffer |
| 中文描述： | 2.05 A SWITCHING REGULATOR, 1250 kHz SWITCHING FREQ-MAX, PDSO24 |
| 封裝： | 4.40 MM, 1.10 MM HEIGHT, MO-153AD, TSSOP-24 |
| 文件頁數(shù)： | 23/38頁 |
| 文件大?。?/td> | 1051K |
| 代理商： | MAX1880EUG |
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M
Quad-Output TFT LCD DC-DC
Converters with Buffer
______________________________________________________________________________________
23
times, the amplifier
’
s transconductance increases as
the output current increases (see
Typical Operating
Characteristics
).
The VCOM buffer
’
s positive feedback input features
dual mode operation. The buffer
’
s output voltage can
be internally set by a 50% resistive divider connected
to the buffer
’
s supply voltage (SUPB), or the output volt-
age can be externally adjusted for other voltages.
Shutdown (SHDN)
A logic-low level on
SHDN
shuts down all of the con-
verters and the reference. When shut down, the supply
current drops to 0.1μA to maximize battery life, and the
reference is pulled to ground. The output capacitance,
feedback resistors, and load current determine the rate
at which each output voltage will decay. A logic-level
high on
SHDN
power activates the MAX1778/
MAX1880
–
MAX1885 (see Power-Up Sequencing). Do
not leave
SHDN
floating. If unused, connect
SHDN
to
IN. A logic-level transition on
SHDN
clears the fault
latch.
Power-Up Sequencing
Upon power-up or exiting shutdown, the MAX1778/
MAX1880
–
MAX1885 start a power-up sequence. First,
the reference powers up. Then, the main DC-DC step-
up converter powers up with soft-start enabled. The lin-
ear regulator powers up at the same time as the main
step-up converter; however, the power sequence and
ready output signal are not affected by the regulation of
the linear regulator. While the main step-up converter
powers up, the output of the PWM comparator remains
low (Figure 2), and the step-up converter charges the
output capacitors, limited only by the maximum duty
cycle and current-limit comparator. When the step-up
converter approaches its nominal regulation value and
the PWM comparator
’
s output changes states for the
first time, the negative charge pump turns on. When the
negative output voltage reaches approximately 90% of
its nominal value (V
FBN
< 110mV), the positive charge
pump starts up. Finally, when the positive output volt-
age reaches 90% of its nominal value (V
FBP
> 1.125V),
the active-low ready signal (
RDY
) goes low (see
Power
Ready)
, and the VCOM buffer powers up. The
MAX1883/MAX1884/MAX1885 do not contain the
charge pumps, but the power-up sequence still con-
tains the charge pumps
’
startup logic, which appears
as a delay (2
4096/fOSC) between the step-up con-
verter reaching regulation and when the ready signal
and VCOM buffer are activated.
Soft-Start
For the main step-up regulator, soft-start allows a grad-
ual increase of the current-limit level during startup to
reduce input surge currents. The MAX1778/MAX1880
–
MAX1885 divide the soft-start period into four phases.
During the first phase, the controller limits the current
limit to only 0.38A (see
Electrical Characteristics
),
approximately a quarter of the maximum current limit
SUPB
V
SUPB
4.5V TO 13V
C
BUF
BUFOUT
BUF-
V
BUFOUT
1.2V TO (V
SUPB
- 1.2V)
BUF+
125mV
GND
R12
R
R
R11
V
BUFOUT
=
(
)
V
SUPB
R12
MAX1778
MAX1880
MAX1881
MAX1882
MAX1883
MAX1884
MAX1885
gm
Figure 6. VCOM Buffer Block Diagram
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PDF描述 |
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| MAX1882EUG | Quad-Output TFT LCD DC-DC Converters with Buffer |
| MAX1779 | 32-Bit Digital Signal Controller with ROM 100-LQFP -40 to 125 |
| MAX1779EUE | 32-Bit Digital Signal Controller with ROM 100-LQFP -40 to 125 |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1880EUG+ | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 Quad-Output TFT LCD 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 |
| MAX1880EUG+T | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 Quad-Output TFT LCD 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 |
| MAX1880EUG-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 |
| MAX1881EUG | 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 |
| MAX1881EUG+ | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 Quad-Output TFT LCD 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 |
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