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| 型號： | AD8531AR |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 運動控制電子 |
| 英文描述： | Low Cost, 250 mA Output Single-Supply Amplifiers |
| 中文描述： | OP-AMP, 30000 uV OFFSET-MAX, 2.2 MHz BAND WIDTH, PDSO8 |
| 封裝： | MS-012AA, SOIC-8 |
| 文件頁數(shù)： | 10/16頁 |
| 文件大?。?/td> | 417K |
| 代理商： | AD8531AR |
AD8531/AD8532/AD8534
REV. D
–10–
This input current is not inherently damaging to the device as
long as it is limited to 5 mA or less. For the AD8531/AD8532/
AD8534, once the input voltage exceeds the supply by more
than 0.6 V the input current quickly exceeds 5 mA. If this
condition continues to exist, an external series resistor should
be added. The size of the resistor is calculated by dividing the
maximum overvoltage by 5 mA. For example, if the input
voltage could reach 10 V, the external resistor should be (10 V/
5 mA) = 2 k
W
. This resistance should be placed in series with
either or both inputs if they are exposed to an overvoltage con-
dition. For more information on general overvoltage character-
istics of amplifiers refer to the
1993 Seminar Applications Guide
,
available from the Analog Devices Literature Center.
Output Phase Reversal
Some operational amplifiers designed for single-supply opera-
tion exhibit an output voltage phase reversal when their inputs
are driven beyond their useful common-mode range. The
AD8531/AD8532/AD8534 is free from reasonable input voltage
range restrictions provided that input voltages no greater than
the supply voltage rails are applied. Although the device’s out-
put will not change phase, large currents can flow through
internal junctions to the supply rails, as was pointed out in the
previous section. Without limit, these fault currents can easily
destroy the amplifier. The technique recommended in the
input overvoltage protection section should therefore be applied
in those applications where the possibility of input voltages
exceeding the supply voltages exists.
Capacitive Load Drive
The AD8531/AD8532/AD8534 exhibits excellent capacitive
load driving capabilities. It can drive up to 10 nF directly as
shown in Figures 21 through 24. However, even though the
device is stable, a capacitive load does not come without a
penalty in bandwidth. As shown in Figure 35, the bandwidth is
reduced to under 1 MHz for loads greater than 10 nF. A “snub-
ber” network on the output won’t increase the bandwidth, but
it does significantly reduce the amount of overshoot for a given
capacitive load. A snubber consists of a series R-C network
(R
S
, C
S
), as shown in Figure 36, connected from the output of
the device to ground. This network operates in parallel with the
load capacitor, C
L
, to provide phase lag compensation. The actual
value of the resistor and capacitor is best determined empirically.
CAPACITIVE LOAD – nF
4
3.5
0
0.01
100
0.1
B
1
10
2
1.5
1
0.5
3
2.5
V
S
= 2.5V
R
L
= 1k
T
A
= 25 C
Figure 35. Unity-Gain Bandwidth vs. Capacitive Load
5V
R
S
5
V
OUT
V
IN
100mV p-p
AD8532
C
L
47nF
C
S
1 F
Figure 36. Snubber Network Compensates for Capacitive
Loads
The first step is to determine the value of the resistor, R
S
. A
good starting value is 100
W
. This value is reduced until the
small-signal transient response is optimized. Next, C
S
is deter-
mined—10
m
F is a good starting point. This value is reduced to
the smallest value for acceptable performance (typically, 1
m
F).
For the case of a 47 nF load capacitor on the AD8531/AD8532/
AD8534, the optimal snubber network is a 5
W
in series with
1
m
F. The benefit is immediately apparent as seen in the scope
photo in Figure 37. The top trace was taken with a 47 nF load
and the bottom trace with the 5
W
—1
m
F snubber network in
place. The amount of overshoot and ringing is dramatically
reduced. Table I below illustrates a few sample snubber networks
for large load capacitors:
Table I. Snubber Networks for Large Capacitive Loads
Load Capacitance
(C
L
)
0.47 nF
4.7 nF
47 nF
Snubber Network
(R
S
, C
S
)
300
W
, 0.1
m
F
30
W
, 1
m
F
5
W
, 1
m
F
47nF LOAD
ONLY
SNUBBER
IN CIRCUIT
100
90
10
0%
50mV
10 s
50mV
Figure 37. Overshoot and Ringing Is Reduced by Adding
a Snubber Network in Parallel with the 47 nF Load
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| AD8531AR-REEL | 制造商:Analog Devices 功能描述:OP Amp Single GP R-R I/O 6V 8-Pin SOIC N T/R |
| AD8531ART | 制造商:AD 制造商全稱:Analog Devices 功能描述:Low Cost, 250 mA Output Single-Supply Amplifiers |
| AD8531ART-REEL | 制造商:Analog Devices 功能描述:OP Amp Single GP R-R I/O 6V 5-Pin SOT-23 T/R 制造商:Rochester Electronics LLC 功能描述:SINGLE 250MA RAIL TO RAIL OP AMP - Tape and Reel |
| AD8531ART-REEL7 | 制造商:Analog Devices 功能描述:OP Amp Single GP R-R I/O 6V 5-Pin SOT-23 T/R 制造商:Rochester Electronics LLC 功能描述:SINGLE 250MA RAIL TO RAIL OP AMP - Tape and Reel |
| AD8531ARTZ-REEL | 功能描述:IC OPAMP GP R-R CMOS SOT23-5 RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標準包裝:160 系列:- 放大器類型:通用 電路數(shù):4 輸出類型:滿擺幅 轉換速率:10 V/µs 增益帶寬積:9MHz -3db帶寬:- 電流 - 輸入偏壓:1pA 電壓 - 輸入偏移:250µV 電流 - 電源:730µA 電流 - 輸出 / 通道:28mA 電壓 - 電源，單路/雙路(±):2.7 V ~ 5.5 V，±1.35 V ~ 2.75 V 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:16-SOIC（0.154"，3.90mm 寬） 供應商設備封裝:16-SOIC N 包裝:管件 |
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