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參數(shù)資料
| 型號： | LM1276AAA/NA |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 音頻／視頻放大 |
| 英文描述： | 1 CHANNEL, VIDEO PREAMPLIFIER, PDIP28 |
| 封裝： | PLASTIC, DIP-28 |
| 文件頁數(shù)： | 2/50頁 |
| 文件大?。?/td> | 6075K |
| 代理商： | LM1276AAA/NA |
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SYSTEM INTERFACE SIGNALS
The Horizontal Sync, Flyback, Vertical Sync, and the Clamp
input signals are important for proper functionality of the
LM1276. Both blanking inputs must be present for OSD syn-
chronization. In addition, the Horizontal blanking input also
assists in setting the proper cathode black level, along with
the Clamping pulse. The Vertical blanking input initiates a
blanking level at the LM1276 outputs, which is programmable
from 3 to 127 lines (at least 10 is recommended). This input
is set up to only accept a vertical sync pulse, and the leading
edge is used to start the programmable vertical blanking sig-
nal directly. The start position of the internal Horizontal blank-
ing pulse is programmable from 0 to 64 pixels ahead of the
start position of the Horizontal flyback input. Both horizontal
and vertical blanking can be individually disabled, if desired.
it is logic level and the Vertical input (which must always be
logic level). Figure 3 shows the smaller pin 28 voltage super-
imposed on the horizontal blanking pulse input to the neck
board with R
H = 4.7k and C1 = 0.1 F. Note where the voltage
at pin 28 is clamped to about 1V when the pin is sinking cur-
rent. Figure 4 shows the smaller pin 1 voltage superimposed
on the vertical blanking input to the neck board with R
V = 4.7k.
These component values correspond to the application circuit
of Figure 9.
Please note that the Horizontal Flyback signal to pin 28 MUST
be continuously provided to the IC, even during energy save
or sleep modes. In the application, this signal should be al-
ways generated whether the VGA cable is disconnected, the
monitor is in energy save mofe, or sleep mode.
Figure 5 show the case where the horizontal input is from de-
flection. Figure 5 shows the pin 28 voltage which is derived
from a horizontal flyback pulse of 35V peak to peak with R
H
= 8.2K and C
1 jumpered.
Figure 6 shows the pin 27 clamp input voltage superimposed
on the neck board clamp logic input pulse. R = 1k and should
be chosen to limit the pin 27 voltage to about 2.5V peak to
peak. This corresponds to the application circuit given in Fig-
ure 9. The clamp input pin can also be internally connected
to the Horizontal Sync pin, thus eliminating the need for a
Clamp signal supplied to the neckboard. This can be enabled
with register 0x853E[4].
H SYNC & V SYNC
V Sync at pin 1 and H Sync at pin 15 must be supplied with
logic level signals generated by the MCU. In an application
where a logic level clamp pulse is used, the same signal can
be used for the H Sync input. It is important that both V Sync
and H Sync are always receiving signals, even during VGA
cable disconnect, energy save mode, or sleep mode.
CATHODE RESPONSE
Figure 7 shows the response at the red cathode for the ap-
1.5 ns. The resulting leading edge has a 7.1 ns rise time and
7.6% overshoot, while the trailing edge has a 7.1 ns rise time
and 6.9% overshoot using an LM2467 driver.
ABL GAIN REDUCTION
The ABL function reduces the contrast level of the LM1276
as the voltage on pin 26 is lowered from V
CC to around 2V.
Figure 8 shows the amount of gain reduction as the voltage
is lowered from V
CC (5.0V) to 2V. The gain reduction is small
until V
26 reaches the knee around 3.7V, where the slope in-
creases. Many system designs will require about 3 dB to
5 dB of gain reduction in full beam limiting. Additional atten-
uation is possible, and can be used in special circumstances.
However, in this case, video performance such as video lin-
earity and tracking between channels will tend to depart from
normal specifications.
The onset of ABL in the LM1276 is adjustable so that the
amount of beam limiting can be varied, especially for larger
Hi-Brite window displays where the contrast level is not de-
sired to be reduced as much as a normal video display. The
beam current limiting is 4-bit adjustable in steps of 80 A each
all the way up to a delta of 1.2 mA. The value of the ABL pull
up resistor (R2) to the external +80V supply must be selected
carefully such that the ABL threshold current will be at the
desired maximum (i.e. 2 mA) when register 0x85C4 is at the
lowest setting, 0x00.
There are 4 different ABL current registers corresponding to
4 different ABL settings. Each setting or register (0x85C4 -
0x85C7) can be assigned a different ABL current threshold.
ABL current register 0 can correspond to a minimal area of
the screen being highlighted, and ABL current register 4 can
correspond to the maximum area of the screen being high-
lighted. This area is calculated by the HiBrite software, and
the particular ABL register that is is to be activated is selected
by the software. The values of each register are written by the
MCU.
www.national.com
10
200969 Version 2 Revision 4
Print Date/Time: 2011/07/11 11:20:12
LM1276
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參數(shù)描述 |
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| LM1279AN | 功能描述:IC AMP RGB VIDEO SYSTEM 20-DIP RoHS:否 類別:集成電路 (IC) >> 線性 - 放大器 - 視頻放大器和頻緩沖器 系列:- 標(biāo)準(zhǔn)包裝:1,000 系列:- 應(yīng)用:驅(qū)動器 輸出類型:差分 電路數(shù):3 -3db帶寬:350MHz 轉(zhuǎn)換速率:1000 V/µs 電流 - 電源:14.5mA 電流 - 輸出 / 通道:60mA 電壓 - 電源，單路/雙路(±):5 V ~ 12 V，±2.5 V ~ 6 V 安裝類型:表面貼裝 封裝/外殼:20-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:20-QFN 裸露焊盤（4x4） 包裝:帶卷 (TR) |
| LM1279DL WAF | 制造商:Texas Instruments 功能描述: |
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