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參數(shù)資料
| 型號： | MAX1889EGE |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Triple-Output TFT LCD Power Supply with Fault Protection |
| 中文描述： | 2.8 A SWITCHING REGULATOR, 1250 kHz SWITCHING FREQ-MAX, QCC16 |
| 封裝： | 5 X 5 MM, 0.90 MM HEIGHT, THIN, QFN-16 |
| 文件頁數(shù)： | 22/32頁 |
| 文件大小： | 796K |
| 代理商： | MAX1889EGE |
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M
Triple-Output TFT LCD Power Supply
with Fault Protection
22
______________________________________________________________________________________
The transistor
’
s current gain limits the guaranteed maxi-
mum output current to:
where I
DRV
is the minimum base-drive current, and R
BE
is the pullup resistor connected between the transis-
tor
’
s base and emitter. Furthermore, the transistor
’
s cur-
rent gain increases the linear regulator
’
s DC loop gain
(see the
Stability Requirements
section), so excessive
gain destabilizes the output. Therefore, transistors with
current gain over 100 at the maximum output current
are not recommended. The transistor
’
s input capaci-
tance and input resistance also create a second pole,
which could be low enough to make the output unsta-
ble when heavily loaded.
The transistor
’
s saturation voltage at the maximum output
current determines the minimum input-to-output voltage
differential that the linear regulator supports.
Alternatively, the package
’
s power dissipation could limit
the usable maximum input-to-output voltage differential.
The maximum power dissipation capability of the transis-
tor
’
s package and mounting must exceed the actual
power dissipation in the device. The power dissipation
equals the maximum load current times the maximum
input-to-output voltage differential:
During startup, the LDO outputs are below their respec-
tive setpoints, and the base drive to the pass transis-
tors is a maximum. The large drive currents can cause
the charge-pump outputs to collapse. If the charge-
pump loading is objectionable, base resistors can be
added between the drive outputs (DRVN and DRVP)
and the pass transistors (Figure 7). These resistors limit
the maximum drive current and prevent discharging the
charge pump
’
s output capacitors. Select the minimum
base drive current to meet the maximum required LDO
output current:
The resistance required to guarantee this base current is:
As a consequence of adding the base resistors, a volt-
age change at DRVN and DRVP accompanies changes
in drive current. This voltage change can be coupled
through parasitic capacitance to the LDO feedback
pins. If the rate of voltage change is sufficiently large, it
can cause instability.
R
V
V
I
V
V
I
BASE
LDOIN MAX
BE
DRIVE(
(
MIN
β
LDOIN MAX
BE
LDOOUT MAX
≤
=
)
(
)
)
(
)
(
)
-
-
I
I
DRIVE MIN
LDOOUT MAX
β
MIN
(
)
(
)
=
P I
I
LOAD MAX
V
V
V
LOAD MAX
LDOIN
LDOOUT
CE
=
(
)
(
)
(
)
-
I
I
V
R
LOAD MAX
DRV
BE
BE
MIN
β
(
)
=
-
DRVP
FBP
DRVN
FBN
Q1
Q2
V
PL
7
6
8
9
REF
R20
51k
R19
15k
C24
2200pF
C20
470pF
V
NL
V
N
V
P
MAX1889
Figure 7. Limiting LDO Drive Current During Startup
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1889EGE+ | 制造商:Maxim Integrated Products 功能描述:TRIPLE-OUTPUT TFT LCD POWER SUPPLY WITH FAULT PROTECTION - Rail/Tube |
| MAX1889ETE | 功能描述:LCD 驅(qū)動器 RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
| MAX1889ETE+ | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 Quad-Output TFT LCD Power Supply 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 |
| MAX1889ETE+T | 功能描述:LCD 驅(qū)動器 Quad-Output TFT LCD Power Supply RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
| MAX1889ETE-T | 功能描述:LCD 驅(qū)動器 RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
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