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參數(shù)資料
| 型號(hào)： | BUF20800 |
| 英文描述： | 18-Channel GAMMA VOLTAGE GENERATOR with Two Programmable VCOM Channels |
| 中文描述： | 18通道伽瑪雙通道可編程的VCOM電壓發(fā)生器 |
| 文件頁數(shù)： | 14/27頁 |
| 文件大小： | 765K |
| 代理商： | BUF20800 |
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SBOS329D JUNE 2005 REVISED OCTOBER 2006
www.ti.com
14
PROGRAMMABLE V
COM
The V
COM
channels of the BUF20800 can swing to 2V from
the positive supply rail while sourcing 100mA and to 1V
above the negative rail while sinking 100mA (see Figure 4,
typical characteristic
Output Voltage vs Output Current
).
To store the gamma and the V
COM
values, an external
EEPROM is required. During power-up of the LCD panel,
the timing controller can then read the EEPROM and load
the values into the BUF20800 to generate the desired
V
COM
voltages, as illustrated in Figure 11 and Figure 12.
The V
COM
channels can be programmed independently
from the gamma channels.
BUF20800
SDA
SCL
R
Control Interface
Gamma
References
OUT1
OUT2
OUT17
OUT18
V
COM
V
COM OUT1
V
COM OUT2
Figure 12. BUF20800 Used for Programmable
V
COM
REFH AND REFL INPUT RANGE
Best performance and output swing range of the
BUF20800 are achieved by applying REFH and REFL
voltages that are slightly below the power-supply
voltages. Most specifications have been tested at
REFH = V
200mV and REFL = GND + 200mV. The
REFH internal buffer is designed to swing very closely to
V and the REFL internal buffer to GND. However, there
is a finite limit on how close they can swing before
saturating. To avoid saturation of the internal REFH and
REFL buffers, the REFH voltage should not be greater
than V 100mV and REFL voltage should not be lower
than GND + 100mV. Figure 13 shows the swing capability
of the REFH and REFL buffers.
The other consideration when trying to maximize the
output swing capability of the gamma buffers is the
limitation in the swing range of output buffers (OUT118,
V
COM
1, and V
COM
2), which depends on the load current. A
typical load in the LCD application is 510mA. For
example, if OUT1 is sourcing 10mA, the swing is typically
limited to about V 200mV. The same applies to OUT18,
which typically limits at GND + 200mV when sinking
10mA. An increase in output swing can only be achieved
for much lighter loads. For example, a 3mA load typically
allows the swing to be increased to approximately V
100mV and GND + 100mV.
Connecting REFH directly to V and REFL directly to GND
does not damage the BUF20800. As discussed above
however, the output stages of the REFH and REFL buffers
will saturate. This condition is not desirable and can result
in a small error in the measured output voltages of
OUT118, V
COM
1, and V
COM
2. As described above, this
method of connecting REFH and REL does not help to
maximize the output swing capability.
18
17
16
15
3
2
1
0
O
0
10
20
100
40
50
60
70
80
90
30
Output Current (mA)
REFL OUT (sinking), Code = 000h
V
REFL
= 0.2V, V
REFH
= 17V
R
LOAD
Connected to 18V
REFH OUT (sourcing), Code = 3FFh
V
REFL
= 1V, V
REFH
= 17.8V
R
LOAD
Connected to GND
Figure 13. Reference Buffer Output Voltage vs
Output Current
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| BUF298AF | TRANSISTOR | BJT POWER MODULE | INDEPENDENT | 450V V(BR)CEO | 50A I(C) |
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| BUF20800AIDCPR | 功能描述:LCD Gamma緩沖器 18-Ch Vltg Generator w/2 Prog VCOM Chs 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 |
| BUF20800AIDCPRE4 | 功能描述:LCD Gamma緩沖器 18-Ch Vltg Generator w/2 Prog VCOM Chs 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 |
| BUF20800ATDCPRQ1 | 功能描述:LCD Gamma緩沖器 AUTO CAT 18CH GAMMA VLTG GEN 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 |
| BUF20800-Q1 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:18-CHANNEL GAMMA VOLTAGE GENERATOR WITH TWO PROGRAMMABLE VCOM CHANNELS |
| BUF20820 | 制造商:BB 制造商全稱:BB 功能描述:18-Channel GAMMA VOLTAGE GENERATOR with Two Programmable VCOM Channels |
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