- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄377718 > LT1942EUF (LINEAR TECHNOLOGY CORP) Quad DCDC Converter for Triple Outputs TFT Supply Plus LED Driver PDF資料下載
參數(shù)資料
| 型號(hào)： | LT1942EUF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Quad DCDC Converter for Triple Outputs TFT Supply Plus LED Driver |
| 中文描述： | 4 A SWITCHING REGULATOR, 1200 kHz SWITCHING FREQ-MAX, PQCC24 |
| 封裝： | 4 X 4 MM, 0.75 MM HEIGHT, PLASTIC, MO-220WGGD, QFN-24 |
| 文件頁數(shù)： | 11/16頁 |
| 文件大小： | 248K |
| 代理商： | LT1942EUF |
LT1942
11
1942fa
APPLICATIU
W
U
U
Setting the Output Voltages
Unlike charge-pump-based TFT supplies, the LT1942 TFT
outputs can all be independently set. The AV
DD
, V
OFF
and
V
ON
outputs are all inductively based DC/DC converters.
As such, the output voltages are set by choosing the right
feedback divider ratio. The AV
DD
feedback pin is FB1 and
the reference voltage is 1.25V. The V
OFF
feedback pin is
NFB2 and the reference voltage is –150mV. The V
ON
feedback pin is FB3 and the reference voltage is 1.25V. The
LED driver is also an inductively based DC/DC converter.
Output Disconnect
The V
ON
switching regulator has built in output discon-
nect. When the V
ON
supply is enabled, the boost converter
will charge up the D3 node. With the output disconnect
PNP (Q5) turned off, the voltage on V
OUT3
will be zero.
Once the power sequencing circuitry turns on the PNP,
V
OUT3
will go to nearly the same voltage as D3.
The V
OFF
switching regulator naturally achieves output
disconnect due to the switching topology (inverting con-
figuration). When the LT1942 is in shutdown, V
OFF
will go
to zero volts.
The AV
DD
switching regulator provides a PGOOD pin to be
used for an external output disconnect function. This pin
can drive the gate of a PMOS device. When the LT1942 is
first enabled, the AV
DD
switching regulator begins to
charge up the output capacitor. Since PGOOD is still an
open collector at this point, the PMOS device is turned off,
leaving the AV
DD
output at zero volts. Once the output
capacitor charges to 97% of the final value, PGOOD
latches low turning on the PMOS device and bringing the
AV
DD
output quickly to the desired voltage.
Soft-Start
The higher current regulators, AV
DD
and LED, have user
programmable soft-start functions built into the part.
Simply place a capacitor from the SS1 pin to GND to
achieve soft-start for the AV
DD
switcher. For the LED
switcher, place a capacitor from the SS4 pin to GND. A
good value for both soft-start capacitors is 0.1
μ
F. The
soft-start time is dependent on the load characteristics
which will vary depending on the type and size of the TFT
display. It is a good practice to experiment to determine
the best value for the soft-start capacitors.
Power Sequencing
The TFT supply has integrated supply sequencing built-in
to ensure proper initiation of the TFT display. Figure 1
shows a state diagram of the power sequencing circuitry.
The power sequencing circuitry insures that the AV
DD
supply comes up first, then the negative V
OFF
supply and
lastly the V
ON
positive supply. To pick the CT capacitor for
a particular delay, use the following equation:
C
A t
μ
10
V
T
DELAY
=
0 7
.
Figure 2 shows the power sequencing during start-up of
the TFT power supply for the circuit shown in the figure on
the first page of this data sheet. All bias supplies start up
in a well controlled and well timed manner. The LED
backlight driver is independently controlled via the CTRL4
pin.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LT1943 | High Current Quad Output Regulator for TFT LCD Panels |
| LT1943EFE | High Current Quad Output Regulator for TFT LCD Panels |
| LT1944 | 1.4A, 1.5MHz Synchronous Step-Up DC/DC Converter with Output Disconnect |
| LT1944-1 | Dual Micropower Step-Up DC/DC Converter |
| LT1944-1EMS | Dual Micropower Step-Up DC/DC Converter |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT1942EUF#PBF | 功能描述:IC REG SW QUAD TFT LCD 24-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
| LT1942EUF#TRPBF | 功能描述:IC REG SW QUAD TFT LCD 24-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
| LT1942EUFPBF | 制造商:Linear Technology 功能描述:Conv DC-DC Quad Inv/Step-Up 16V QFN24EP |
| LT1943 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Quad DCDC Converter for Triple Outputs TFT Supply Plus LED Driver |
| LT1943_1 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:High Current Quad Output Regulator for TFT LCD Panels |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。