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參數資料
| 型號： | THS7374IPWR |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 音頻／視頻放大 |
| 英文描述： | 4 CHANNEL, VIDEO AMPLIFIER, PDSO14 |
| 封裝： | GREEN, PLASTIC, TSSOP-14 |
| 文件頁數： | 16/40頁 |
| 文件大小： | 929K |
| 代理商： | THS7374IPWR |
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Level
Shift
Internal
Circuitry
+3.3V
800kW
R
PU
Input
Pin
Input
C
0.1 F
m
IN
V
=V
DC
S
800kW
800k
+R
W
PU
www.ti.com
SLOS590B – JULY 2008 – REVISED JANUARY 2011
To ensure proper stability of the ac STC control loop,
300 mV)/2 = 0.65 V. Thus, the pull-up resistor
the source impedance must be less than 1-k
with
calculates to a standard 3.3-M
resistor, resulting in
the input capacitor in place. Otherwise, there is a
0.644 V. If the output dc-bias point is desired to be
possibility for the control loop to ring; this ringing may
1.6 V with a 5-V power supply, then the pull-up
appear on the THS7374 output. Because most DACs
resistor
value
calculates
to
be
approximately
or encoders use resistors to establish the voltage,
5.36-M
.
which are typically less than 300-
, meeting the less
Keep in mind that the internal 800-k
resistor has a
than 1-k
requirement is easily done. However, if the
±20% variance. As such, the calculations should take
source impedance looking from the THS7374 input
this variance into account. For the 0.644-V input bias
perspective is very high, simply adding a 1-k
voltage example above using an ideal 3.3-M
resistor to GND ensures proper operation of the
resistor, the input dc bias voltage is about 0.644 V
THS7374.
(±0.1 V).
INPUT MODE OF OPERATION: AC BIAS
The value of the output bias is very flexible and is left
to each individual design. It is important to ensure
Sync tip clamps are ideal for signals that have
that the signal does not clip or saturate the video
horizontal and/or vertical syncs associated with them.
signal. Thus, it is recommended to ensure the output
However, some video signals do not have a sync
bias voltage is between 0.9 V and (VS+ – 1 V). For
embedded within the signal. If ac-coupling of these
100%
color
saturated
CVBS
or
signals
with
signals is desired, then a dc bias is required to
Macrovision, the CVBS signal can reach up to 1.23
properly set the dc operating point within the
VPP input, or 2.46 VPP output. In contrast, other
THS7374. This function is easily accomplished with
signals are typically 0.7 VPP input, or 1.4 VPP output.
the THS7374 by simply adding an external pull-up
As such, the output bias voltage must account for a
resistor to the positive power supply, as shown in
worst-case situation depending on the potential
signals.
One other issue that must be taken into account is
the dc-bias point as a function of the power supply.
As such, there is an impact on the system PSRR. To
help reduce this impact, the input capacitor combines
with the pull-up resistance to function as a low-pass
filter. Additionally, the time to charge the capacitor to
the final dc bias point is also a function of the pull-up
resistor and the input capacitor. Lastly, the input
capacitor forms a high-pass filter with the parallel
impedance of the pull-up resistor and the 800-k
resistor. In general, it is good to have this high-pass
filter at approximately 3-Hz to minimize any potential
droop on a P’B, P’R, or non-sync B’ or R’ signal. A
Figure 60. AC-Bias Input Mode Circuit
0.1-mF input capacitor with a 3.3-M pull-up resistor
Configuration
equates to a 2.5-Hz high-pass corner frequency.
This mode of operation is recommended for use with
The dc voltage that appears at the input pin is equal
chroma (C’), P’B, P’R, U’, V’, and non-sync R'G'B’
to Equation 1:
signals. This method can also be utilized with signals
with sync if desired. The benefit of using the STC
function is that it maintains a constant back porch
(1)
voltage as opposed to a back porch voltage that
fluctuates depending on the video content. Because
The THS7374 allowable input range is approximately
the corner frequency of the input is a very low 2.5 Hz,
0 V to (VS+ – 1.5 V), which allows for a very wide
then this is still very good performance, but not as
input voltage range. As such, the input dc bias point
good relative to a STC configuration.
is very flexible; the output dc bias point is the primary
factor. For example, if the output dc bias point is
desired to be mid-rail on a 3.3-V supply, then the
input dc bias point is recommended to be (1.6 V –
Copyright 2008–2011, Texas Instruments Incorporated
23
Product Folder Link(s): THS7374
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| THS7374IPW | 4 CHANNEL, VIDEO AMPLIFIER, PDSO14 |
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| THS7374IPWRG4 | 4 CHANNEL, VIDEO AMPLIFIER, PDSO14 |
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相關代理商/技術參數 |
參數描述 |
|---|---|
| THS7374IPWRG4 | 功能描述:視頻放大器 4-Ch SDTV Video Amp RoHS:否 制造商:ON Semiconductor 通道數量:4 電源類型: 工作電源電壓:3.3 V, 5 V 電源電流: 最小工作溫度: 最大工作溫度: 封裝 / 箱體:TSSOP-14 封裝:Reel |
| THS7375 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:4-Channel SDTV Video Amplifier with 6th-Order Filters and 5.6-V/V Gain |
| THS7375EVM | 功能描述:放大器 IC 開發工具 THS7375 Eval Mod RoHS:否 制造商:International Rectifier 產品:Demonstration Boards 類型:Power Amplifiers 工具用于評估:IR4302 工作電源電壓:13 V to 23 V |
| THS7375IPW | 功能描述:視頻放大器 4Ch SDTV Video Amp RoHS:否 制造商:ON Semiconductor 通道數量:4 電源類型: 工作電源電壓:3.3 V, 5 V 電源電流: 最小工作溫度: 最大工作溫度: 封裝 / 箱體:TSSOP-14 封裝:Reel |
| THS7375IPWG4 | 功能描述:視頻放大器 4Ch SDTV Video Amp w/6th order fltr RoHS:否 制造商:ON Semiconductor 通道數量:4 電源類型: 工作電源電壓:3.3 V, 5 V 電源電流: 最小工作溫度: 最大工作溫度: 封裝 / 箱體:TSSOP-14 封裝:Reel |
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