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參數(shù)資料
| 型號(hào)： | OPA832ID |
| 英文描述： | Low-Power, Single-Supply, Fixed-Gain Video Buffer Amplifier |
| 中文描述： | 低功耗，單電源，固定增益視頻緩沖放大器 |
| 文件頁數(shù)： | 17/26頁 |
| 文件大?。?/td> | 471K |
| 代理商： | OPA832ID |
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SBOS266B JUNE 2003 REVISED SEPTEMBER 2004
OPERATING SUGGESTIONS
GAIN SETTING
Setting the gain for the OPA832 is very easy. For a gain of
+2, ground the IN pin and drive the +IN pin with the signal.
For a gain of +1, either leave the IN pin open and drive the
+IN pin or drive both the +IN and IN pins as shown in
Figure 7. For a gain of 1, ground the +IN pin and drive the
IN pin with the input signal. An external resistor may be
used in series with the IN pin to reduce the gain. However,
since the internal resistors (R
F
and R
G
) have a tolerance
and temperature drift different than the external resistor,
the absolute gain accuracy and gain drift over temperature
will be relatively poor compared to the previously
described standard gain connections using no external
resistor.
www.ti.com
17
This circuit removes the peaking by bootstrapping out any
parasitic effects on R
G
. The input impedance is still set by
R
M
as the apparent impedance looking into R
G
is very
high. R
M
may be increased to show a higher input
impedance, but larger values will start to impact DC output
offset voltage. This circuit creates an additional input offset
voltage as the difference in the two input bias current times
the impedance to ground at V
IN
. Figure 8 shows a
comparison of small-signal frequency response for the
unity-gain buffer of Figure 2 (with V
CM
removed from R
G
)
compared to the improved approach shown in Figure 7.
OPA832
V
OUT
V
IN
R
G
400
R
O
75
R
F
400
R
M
50
+5V
Figure 7. Improved Unity-Gain Buffer
UNITY-GAIN BUFFER
This buffer can simply be realized by not connecting R
to
ground. This type of realization shows a peaking in the
frequency response. A similar circuit that holds a flat
frequency response giving improved pulse fidelity is
shown in Figure 7.
6
3
0
3
6
9
12
Frequency (MHz)
G
1
10
100
400
G = +1 Buffer
R
G
Floating
G = +1 Buffer
Figure 5
Figure 8. Buffer Frequency Response
Comparison
OUTPUT CURRENT AND VOLTAGES
The OPA832 provides outstanding output voltage
capability. Under no-load conditions at +25
°
C, the output
voltage typically swings closer than 90mV to either supply
rail.
The minimum specified output voltage and current
specifications over temperature are set by worst-case
simulations at the cold temperature extreme. Only at cold
startup will the output current and voltage decrease to the
numbers shown in the min/max tables. As the output
transistors deliver power, their junction temperatures will
increase, decreasing their V
BE
s (increasing the available
output voltage swing) and increasing their current gains
(increasing the available output current). In steady-state
operation, the available output voltage and current will
always be greater than that shown in the over-temperature
specifications,
since
the
temperatures will be higher than the minimum specified
operating ambient.
To maintain maximum output stage linearity, no output
short-circuit protection is provided. This will not normally
be a problem, since most applications include a series
matching resistor at the output that will limit the internal
power dissipation if the output side of this resistor is
shorted to ground. However, shorting the output pin
directly to the adjacent positive power-supply pin (8-pin
packages) will possibly destroy the amplifier. If additional
short-circuit protection is required, consider a small series
resistor in the power-supply leads. This will reduce the
available output voltage swing under heavy output loads.
output
stage
junction
DRIVING CAPACITIVE LOADS
One of the most demanding and yet very common load
conditions for an op amp is capacitive loading. Often, the
capacitive load is the input of an ADC—including
additional external capacitance which may be recom-
mended to improve ADC linearity. A high-speed, high
open-loop gain amplifier like the OPA832 can be very
susceptible to decreased stability and closed-loop
response peaking when a capacitive load is placed directly
on the output pin. When the primary considerations are
frequency response flatness, pulse response fidelity,
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| OPA832IDBVR | 功能描述:視頻放大器 Lo-Pwr Single-Supply Fixed-Gain Video Bfr RoHS:否 制造商:ON Semiconductor 通道數(shù)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 |
| OPA832IDBVRG4 | 功能描述:視頻放大器 Lo-Pwr Single-Supply Fixed-Gain Video Bfr RoHS:否 制造商:ON Semiconductor 通道數(shù)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 |
| OPA832IDBVT | 功能描述:視頻放大器 Lo-Pwr Single-Supply Fixed-Gain Video Bfr RoHS:否 制造商:ON Semiconductor 通道數(shù)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 |
| OPA832IDBVTG4 | 功能描述:視頻放大器 Lo-Pwr Single-Supply Fixed-Gain Video Bfr RoHS:否 制造商:ON Semiconductor 通道數(shù)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 |
| OPA832IDG4 | 功能描述:視頻放大器 Lo-Pwr Single-Supply Fixed-Gain Video Bfr RoHS:否 制造商:ON Semiconductor 通道數(shù)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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