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參數(shù)資料
| 型號： | LM8207MT |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 模擬信號調(diào)理 |
| 英文描述： | TFT 18 Gamma Buffer + VCOM Driver + Voltage Reference |
| 中文描述： | SPECIALTY ANALOG CIRCUIT, PDSO48 |
| 封裝： | TSSOP-48 |
| 文件頁數(shù)： | 14/22頁 |
| 文件大?。?/td> | 1393K |
| 代理商： | LM8207MT |
Application Section
(Continued)
GAMMA BUFFERS
This section gives an overview for the applications of the
gamma buffers and also defines the gamma correction
curve. Specifications for the buffers are derived from their
operation range. Also included are the formulas for the real-
ization of the gamma correction curve using external resis-
tors. An overview is given for the gamma voltage accuracy,
using the LM8207 in combination with external resistors.
As discussed in the section entitled “Principle Operation of a
TFT-LCD,” the basic function of the gamma buffers is to
make the gamma correction curve independent of the be-
havior of the column driver. Writing data to each subsequent
pixel will cause load variations. The gamma buffers have a
low impedance output and can handle these variations with-
out changing the gamma correction curve. A typical gamma
correction curve is given in
Figure 8
.
Each buffer covers a part of the correction curve and, there-
fore, has its own specifications. All buffers require that the
output should recover quickly from disturbances caused by
the switching of the column driver. The gamma voltage level
of each buffer (VGMA1…VGMA18) depends on its position
for the levels decrease sequentially. To best utilize the
LM8207, each buffer is optimized for its position in the
gamma correction curve.
Gamma Buffers 1-2
Operating voltage range: V
DD
to V
SS
+2V. Due to the
operating voltage, only negative transitions at the output
are possible. Positive transitions will exceed the supply
voltage V
DD
. These buffers are able to source current to
bias the resistive load of the column driver having an
open collector structure. To meet the operating voltage
range, these outputs need a resistive load connected to a
lower potential sourcing an output current of at least
1 mA.
Gamma Buffers 3-16
Operating voltage range: V
– 1V to V
+ 1V. Due to
the operating range, both positive and negative transi-
tions at the outputs are possible.
Gamma Buffers 17-18
Operating voltage range: V
- 2 to V
. Due to the
operating voltage, only positive transitions at the output
are possible. Negative transitions will exceed the nega-
tive supply voltage V
. These buffers are able to sink
current from the resistive load of the column driver having
an open collector structure. To meet the operating volt-
age range, these outputs need a resistive load connected
to a higher potential sinking an output current of at least
1 mA
Example:
A typical application using the LM8207 is given in
Figure 9
.
The
corresponding
gamma
(VGMA1...VGMA18) is defined in
Table 1
. The Voltage Ref-
erence supplies the 14.4V to the resistor network. The cal-
culations for the resistor values and for setting the Voltage
Reference are shown in the section “Voltage Reference.”
correction
curve
20137922
FIGURE 7. Voltage Reference Headroom vs. Load
Current
20137923
FIGURE 8. Typical Gamma Correction Curve
L
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM8207MT/NOPB | 功能描述:LCD Gamma緩沖器 RoHS:否 制造商:Maxim Integrated 輸入補(bǔ)償電壓: 轉(zhuǎn)換速度: 電源電壓-最大:20 V 電源電壓-最小:9 V 電源電流: 最大功率耗散: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFN-38 封裝:Tube |
| LM8207MTX | 功能描述:LCD 驅(qū)動(dòng)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 |
| LM8207MTX/NOPB | 功能描述:LCD 驅(qū)動(dòng)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 |
| LM825 | 制造商:Pulse Electronics Corporation 功能描述: |
| LM8261 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:RRIO, High Output Current & Unlimited Cap Load Op Amp in SOT23-5 |
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