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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)： | 15/32頁 |
| 文件大?。?/td> | 796K |
| 代理商： | MAX1889EGE |
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M
Triple-Output TFT LCD Power Supply
with Fault Protection
______________________________________________________________________________________
15
Positive Linear-Regulator Controller
The positive linear regulator provides the positive high
voltage for the TFT LCD gate drivers. The high voltage
can be produced using a charge-pump circuit as shown
in Figure 1. Use as many stages as necessary to obtain
the required output voltage (see the
Selecting the
Number of Charge-Pump Stages
section). The positive
linear-regulator controller is an analog gain block with an
open-drain N-channel output. It drives an external PNP
pass transistor with a 3k
base-to-emitter resistor to
post-regulate the charge-pump output (Figure 1). The
regulator controller is designed to be stable with an out-
put capacitor of 0.1μF or more.
To enable the regulator using an external control signal,
apply the logic-control input in series with a signal
diode (Figure 1). Additional delay can be added with
external circuitry.
Note that the voltage rating of the DRVP output is 28V.
If higher voltages are present, an external cascode
NPN transistor should be used with the emitter con-
nected to DRVP, the base to V
MAIN
, and the collector to
the base of the PNP.
Negative Linear-Regulator Controller
The negative linear regulator provides the negative volt-
age required to supply gate drivers in TFT LCD panels.
The negative voltage can be produced using a charge
pump circuit as shown in Figure 1. Use as many stages
as necessary to obtain the required output voltage (see
the
Selecting the Number of Charge-Pump Stages
sec-
tion). The negative linear-regulator controller is an ana-
log gain block with an open-drain P-channel output. It
drives an external NPN pass transistor with a 3k
base-
to-emitter resistor to postregulate the charge-pump out-
put (Figure 1). The regulator controller is designed to
be stable with an output capacitor of 0.1μF or more.
The negative linear regulator is enabled as soon as the
main step-up regulator is enabled. To enable the regula-
tor using an external control signal, apply the logic-control
input through an open-drain output or an N-channel MOS-
FET (Figure 1). Additional delay can be added with exter-
nal circuitry (see the
Applications Information
section).
Note that the voltage rating of the DRVN output is
V
IN
- 28V. If higher voltages are present, an external
cascode PNP transistor should be used with the emitter
connected to DRVN, the base to GND, and the collec-
tor to the base of the NPN.
Undervoltage Lockout (UVLO)
The UVLO comparator of the MAX1889 compares the
input voltage at the IN pin with the UVLO threshold (2.7V
rising, 2.35V falling, typ) to ensure that the input voltage is
high enough for reliable operation. The 350mV (typ) hys-
teresis prevents supply transients from causing a restart.
Once the input voltage exceeds the UVLO threshold, the
controller enables the reference block. Once the refer-
ence is above 1.05V, an internal 12μA current source
pulls the GATE pin low and turns on an external P-chan-
nel MOSFET switch (P1, Figure 1) that connects the input
supply to the regulator. When the input voltage falls below
the UVLO threshold, the controller sets the fault latch and
pulls GATE high with an internal 100
switch to turn off
P1 quickly (Figure 4).
Reference Voltage (REF)
The reference output is nominally 1.25V, and can
source at least 50μA (see the
Typical Operating
Characteristics
). Bypass REF with a 0.22μF ceramic
capacitor connected between REF and GND.
Oscillator Frequency (FREQ)
The internal oscillator frequency is pin programmable.
Connect FREQ to ground for 500kHz operation and to V
IN
for 1MHz operation. Note that the soft-start period scales
with the oscillator frequency (see the
Soft-Start
section).
Shutdown (
SHDN
)
A logic-low signal on the
SHDN
pin disables all device
functions including the reference. When shut down, the
supply current drops to 0.1μA (typ) to maximize battery
life. The output capacitance, feedback resistors, and load
current determine the rate at which each output voltage
decays. A logic-high signal on the
SHDN
pin activates the
MAX1889 (see the
Power-Up Sequencing
section). Do not
leave the pin floating. If unused, connect
SHDN
to IN.
Toggling
SHDN
or cycling IN clears the fault latch.
+
-
+
-
0.625V
12
μ
A
GATE
IN
EN
L
C
IN
Figure 4. External Input P-Channel MOSFET Switch Control
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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(shí)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(shí)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(shí)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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