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參數資料
| 型號： | THS4221DGN |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 音頻／視頻放大 |
| 英文描述： | 1 CHANNEL, VIDEO PREAMPLIFIER, PDSO8 |
| 封裝： | GREEN, POWERPAD, PLASTIC, MSOP-8 |
| 文件頁數： | 11/38頁 |
| 文件大小： | 1219K |
| 代理商： | THS4221DGN |
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THS4221, THS4225
THS4222, THS4226
SLOS399G AUGUST 2002 REVISED JANUARY 2004
www.ti.com
19
the feedback resistor directly under the package on
the other side of the board between the output and
inverting input pins. Even with a low parasitic
capacitance
shunting
the
external
resistors,
excessively high resistor values can create significant
time constants that can degrade performance. Good
axial metal-film or surface-mount resistors have
approximately 0.2 pF in shunt with the resistor. For
resistor values > 2.0 k, this parasitic capacitance can
add a pole and/or a zero below 400 MHz that can
effect circuit operation. Keep resistor values as low as
possible, consistent with load driving considerations.
It has been suggested here that a good starting point
for design would be set the Rf be set to 1.3 k for
low-gain, noninverting applications. Doing this
automatically keeps the resistor noise terms low, and
minimize the effect of their parasitic capacitance.
4. Connections to other wideband devices on the
board may be made with short direct traces or
through onboard transmission lines. For short
connections, consider the trace and the input to the
next device as a lumped capacitive load. Relatively
wide traces (50 mils to 100 mils) should be used,
preferably with ground and power planes opened up
around them. Estimate the total capacitive load and
set RISO from the plot of recommended RISO vs
Capacitive Load. Low parasitic capacitive loads
(<4 pF) may not need an R(ISO), since the THS4222
is nominally compensated to operate with a 2-pF
parasitic load. Higher parasitic capacitive loads
without an R(ISO) are allowed as the signal gain
increases (increasing the unloaded phase margin). If
a long trace is required, and the 6-dB signal loss
intrinsic to a doubly-terminated transmission line is
acceptable, implement a matched impedance
transmission line using microstrip or stripline
techniques (consult an ECL design handbook for
microstrip and stripline layout techniques). A 50-
environment is normally not necessary onboard, and
in fact a higher impedance environment improves
distortion as shown in the distortion versus load plots.
With a characteristic board trace impedance defined
based on board material and trace dimensions, a
matching series resistor into the trace from the output
of the THS4222 is used as well as a terminating shunt
resistor at the input of the destination device.
Remember also that the terminating impedance is the
parallel combination of the shunt resistor and the input
impedance of the destination device: this total
effective impedance should be set to match the trace
impedance. If the 6-dB attenuation of a doubly
terminated transmission line is unacceptable, a long
trace can be series-terminated at the source end only.
Treat the trace as a capacitive load in this case and set
the series resistor value as shown in the plot of R(ISO)
vs Capacitive Load. This setting does not preserve
signal integrity or a doubly-terminated line. If the input
impedance of the destination device is low, there is
some signal attenuation due to the voltage divider
formed by the series output into the terminating
impedance.
5. Socketing a high speed part like the THS4222 is
not recommended. The additional lead length and
pin-to-pin capacitance introduced by the socket can
create a troublesome parasitic network which can
make it almost impossible to achieve a smooth, stable
frequency response. Best results are obtained by
soldering the THS4222 onto the board.
PowerPAD DESIGN CONSIDERATIONS
The THS4222 family is available in a thermally-enhanced
PowerPAD family of packages. These packages are
constructed using a downset leadframe upon which the die
is mounted [see Figure 36(a) and Figure 36(b)]. This
arrangement results in the lead frame being exposed as a
thermal pad on the underside of the package [see
Figure 36(c)]. Because this thermal pad has direct thermal
contact with the die, excellent thermal performance can be
achieved by providing a good thermal path away from the
thermal pad.
The PowerPAD package allows for both assembly and
thermal management in one manufacturing operation.
During the surface-mount solder operation (when the
leads are being soldered), the thermal pad can also be
soldered to a copper area underneath the package.
Through the use of thermal paths within this copper area,
heat can be conducted away from the package into either
a ground plane or other heat dissipating device.
The PowerPAD package represents a breakthrough in
combining the small area and ease of assembly of surface
mount with the heretofore awkward mechanical methods
of heatsinking.
Figure 36. Views of Thermally Enhanced
Package
DIE
Side View (a)
DIE
End View (b)
Thermal
Pad
Bottom View (c)
Although there are many ways to properly heatsink the
PowerPAD package, the following steps illustrate the
recommended approach.
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| THS4221DGNR | 1 CHANNEL, VIDEO PREAMPLIFIER, PDSO8 |
| THS4221DBVR | 1 CHANNEL, VIDEO PREAMPLIFIER, PDSO5 |
| THS4221DG4 | 1 CHANNEL, VIDEO PREAMPLIFIER, PDSO8 |
| THS4222DGNG4 | 1 CHANNEL, VIDEO PREAMPLIFIER, PDSO8 |
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相關代理商/技術參數 |
參數描述 |
|---|---|
| THS4221DGNG4 | 功能描述:高速運算放大器 Low-Distortion High Speed R-to-R Output RoHS:否 制造商:Texas Instruments 通道數量:1 電壓增益 dB:116 dB 輸入補償電壓:0.5 mV 轉換速度:55 V/us 工作電源電壓:36 V 電源電流:7.5 mA 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
| THS4221DGNR | 功能描述:高速運算放大器 Low-Distortion High Speed R-to-R Output RoHS:否 制造商:Texas Instruments 通道數量:1 電壓增益 dB:116 dB 輸入補償電壓:0.5 mV 轉換速度:55 V/us 工作電源電壓:36 V 電源電流:7.5 mA 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
| THS4221DGNRG4 | 功能描述:高速運算放大器 Low-Distortion High Speed R-to-R Output RoHS:否 制造商:Texas Instruments 通道數量:1 電壓增益 dB:116 dB 輸入補償電壓:0.5 mV 轉換速度:55 V/us 工作電源電壓:36 V 電源電流:7.5 mA 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
| THS4221DR | 功能描述:高速運算放大器 Low-Distortion High Speed R-to-R Output RoHS:否 制造商:Texas Instruments 通道數量:1 電壓增益 dB:116 dB 輸入補償電壓:0.5 mV 轉換速度:55 V/us 工作電源電壓:36 V 電源電流:7.5 mA 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
| THS4221DRG4 | 功能描述:高速運算放大器 Low-Distortion High Speed R-to-R Output RoHS:否 制造商:Texas Instruments 通道數量:1 電壓增益 dB:116 dB 輸入補償電壓:0.5 mV 轉換速度:55 V/us 工作電源電壓:36 V 電源電流:7.5 mA 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
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