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參數(shù)資料
| 型號： | LMH6609MAX |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 運算放大器 |
| 英文描述： | 900MHz Voltage Feedback Op Amp |
| 中文描述： | OP-AMP, 2500 uV OFFSET-MAX, PDSO8 |
| 封裝： | SOIC-8 |
| 文件頁數(shù)： | 12/15頁 |
| 文件大?。?/td> | 641K |
| 代理商： | LMH6609MAX |
Application Section
(Continued)
COMPONENT SELECTION AND FEEDBACK RESISTOR
Surface mount components are highly recommended for the
LMH6609. Leaded components will introduce unpredictable
parasitic loading that will interfere with proper device opera-
tion. Do not use wire wound resistors.
The LMH6609 operates best with a feedback resistor of
approximately 250
for all gains of +2 and greater and for 1
and less. With lower gains in particular, large value feedback
resistors will exaggerate the effects of parasitic capacitances
and may lead to ringing on the pulse response and fre-
quency response peaking. Large value resistors also add
undesirable thermal noise. Feedback resistors that are much
below 100
will load the output stage, which will reduce
voltage output swing, increase device power dissipation,
increase distortion and reduce current available for driving
the load.
In the buffer configuration the output should be shorted
directly to the inverting input. This feedback does not load
the output stage because the inverting input is a high imped-
ance point and there is no gain set resistor to ground.
OPTIMIZING DC ACCURACY
The LMH6609 offers excellent DC accuracy. The well-
matched inputs of this amplifier allows even better perfor-
mance if care is taken to balance the impedances seen by
the two inputs. The parallel combination of the gain setting
R
G
and feedback R
F
resistors should be equal to R
SEQ
, the
resistance of the source driving the op amp in parallel with
any terminating Resistor (See
Figure 1
). Combining this with
the non inverting gain equation gives the following param-
eters:
R
F
= A
VRSEQ
R
G
= R
F
/(A
V
1)
For Inverting gains the bias current cancellation is accom-
plished by placing a resistor R
on the non-inverting input
equal in value to the resistance seen by the inverting input
(See
Figure 2
). R
B
= R
F
|| (R
G
+ R
S
)
The additional noise contribution of R
can be minimized by
the use of a shunt capacitor (not shown).
POWER DISSIPATION
The LMH6609 has the ability to drive large currents into low
impedance loads. Some combinations of ambient tempera-
ture and device loading could result in device overheating.
For most conditions peak power values are not as important
as RMS powers. To determine the maximum allowable
power dissipation for the LMH6609 use the following for-
mula:
P
MAX
= (150
o
- T
AMB
)/
θ
JA
Where T
AMB
= Ambient temperature (C) and
θ
JA = Thermal
(C/W). For the SOIC package
θ
JA is 148C/W, for the SOT
it is 250C/W. 150
o
C is the absolute maximum limit for the
internal temperature of the device.
Either forced air cooling or a heat sink can greatly increase
the power handling capability for the LMH6609.
VIDEO PERFORMANCE
The LMH6609 has been designed to provide good perfor-
mance with both PAL and NTSC composite video signals.
The LMH6609 is specified for PAL signals. NTSC perfor-
mance is typically marginally better due to the lower fre-
quency content of the signal. Performance degrades as the
loading is increased, therefore best performance will be
obtained with back-terminated loads. The back termination
reduces reflections from the transmission line and effectively
masks transmission line and other parasitic capacitances
from the amplifier output stage. This means that the device
should be configured for a gain of 2 in order to have a net
gain of 1 after the terminating resistor. (See
Figure 6
)
ESD PROTECTION
The LMH6609 is protected against electrostatic discharge
(ESD) on all pins. The LMH6609 will survive 2000V Human
Body model or 200V Machine model events.
Under closed loop operation the ESD diodes have no effect
on circuit performance. There are occasions, however, when
the ESD diodes may be evident. For instance, if the amplifier
is powered down and a large input signal is applied the ESD
diodes will conduct.
TRANSIMPEDANCE AMPLIFIER
The low input current noise and unity gain stability of the
LMH6609 make it an excellent choice for transimpedance
applications.
Figure 7
illustrates a low noise transimpedance
amplifier that is commonly implemented with photo diodes.
R
sets the transimpedance gain. The photo diode current
multiplied by R
F
determines the output voltage.
20079034
FIGURE 6. Typical Video Application
L
www.national.com
12
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LMH6609MAX/NOPB | 功能描述:運算放大器 - 運放 RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| LMH6609MF | 功能描述:運算放大器 - 運放 RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| LMH6609MF/NOPB | 功能描述:運算放大器 - 運放 RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| LMH6609MF/NOPB | 制造商:Texas Instruments 功能描述:Operational Amplifier (Op-Amp) IC |
| LMH6609MFX | 功能描述:運算放大器 - 運放 RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
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