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參數(shù)資料
| 型號： | AD8644AR2 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Single and Quad +18 V Operational Amplifiers |
| 中文描述： | 單路和四路運(yùn)算放大器18 V |
| 文件頁數(shù)： | 6/8頁 |
| 文件大小： | 303K |
| 代理商： | AD8644AR2 |
AD8614/AD8644
–6–
REV. 0
AD86x4
V
IN
261
V
V
OUT
18V
Figure 23. Output Short-Circuit Protection
Input Overvoltage Protection
As with any semiconductor device, whenever the condition exists for
the input to exceed either supply voltage, attention needs to be paid
to the input overvoltage characteristic. As an overvoltage occurs, the
amplifier could be damaged, depending on the voltage level and the
magnitude of the fault current. When the input voltage exceeds
either supply by more than 0.6 V, internal pin junctions energize,
allowing current to flow from the input to the supplies. Observing
Figure 22, the AD8614/AD8644 has 1.5 k
resistors in series with
each input, which helps limit the current. This input current is not
inherently damaging to the device as long as it is limited to 5 mA or
less. If the voltage is large enough to cause more than 5 mA of cur-
rent to flow, an external series resistor should be added. The size of
this resistor is calculated by dividing the maximum overvoltage by
5 mA and subtracting the internal 1.5 k
resistor. For example, if
the input voltage could reach 100 V, the external resistor should be
(100 V/5 mA) – 1.5 k
= 18.5 k
. This resistance should be placed
in series with either or both inputs if they are subjected to the over-
voltages. For more information on general overvoltage characteristics
of amplifiers refer to the
1993 System Applications Guide
, available
from the Analog Devices Literature Center.
Output Phase Reversal
The AD8614/AD8644 is immune to phase reversal as long as the
input voltage is limited to within the supply rails. Although the
device’s output will not change phase, large currents due to
input overvoltage could result, damaging the device. In applica-
tions where the possibility of an input voltage exceeding the
supply voltage exists, overvoltage protection should be used, as
described in the previous section.
Power Dissipation
The maximum power that can be safely dissipated by the
AD8614/AD8644 is limited by the associated rise in junction
temperature. The maximum safe junction temperature is 150
°
C,
and should not be exceeded or device performance could suffer.
If this maximum is momentarily exceeded, proper circuit opera-
tion will be restored as soon as the die temperature is reduced.
Leaving the device in an “overheated” condition for an extended
period can result in permanent damage to the device.
To calculate the internal junction temperature of the AD86x4,
the following formula can be used:
T
J
=
P
DISS
×
θ
JA
+
T
A
where:
T
J
= AD86x4 junction temperature;
P
DISS
= AD86x4 power dissipation;
θ
JA
= AD86x4 package thermal resistance, junction-to-
ambient; and
T
A
= Ambient temperature of the circuit.
The power dissipated by the device can be calculated as:
P
DISS
= I
LOAD
×
(
V
S
–
V
OUT
)
where:
I
LOAD
is the AD86x4 output load current;
V
S
is the AD86x4 supply voltage; and
V
OUT
is the AD86x4 output voltage.
Figure 24 provides a convenient way to see if the device is being
overheated. The maximum safe power dissipation can be found
graphically, based on the package type and the ambient tem-
perature around the package. By using the previous equation, it
is a simple matter to see if
P
DISS
exceeds the device’s power
derating curve. To ensure proper operation, it is important to
observe the recommended derating curves shown in Figure 24.
AMBIENT TEMPERATURE –
8
C
1.5
0–35
–15
5
25
45
65
85
1.0
0.5
14-LEAD SOIC PACKAGE
u
JA
= 120
8
C/W
14-LEAD TSSOP PACKAGE
u
JA
= 180
8
C/W
5-LEAD SOT-23 PACKAGE
u
JA
= 230
8
C/W
M
Figure 24. Maximum Power Dissipation vs. Temperature
for 5-Lead and 14-Lead Package Types
Unused Amplifiers
It is recommended that any unused amplifiers in the quad pack-
age be configured as a unity gain follower with a 1k
feedback
resistor connected from the inverting input to the output, and
the noninverting input tied to the ground plane.
Capacitive Load Drive
The AD8614/AD8644 exhibits excellent capacitive load driving
capabilities. Although the device is stable with large capacitive
loads, there is a decrease in amplifier bandwidth as the capacitive
load increases.
When driving heavy capacitive loads directly from the AD8614/
AD8644 output, a snubber network can be used to improve the
transient response. This network consists of a series R-C connected
from the amplifier’s output to ground, placing it in parallel with the
capacitive load. The configuration is shown in Figure 25. Although
this network will not increase the bandwidth of the amplifier, it will
significantly reduce the amount of overshoot.
AD86x4
V
IN
V
OUT
5V
R
X
C
X
C
L
Figure 25. Snubber Network Compensation for Capacitive
Loads
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD8644AR-REEL | 制造商:Analog Devices 功能描述:OP Amp Quad GP R-R I/O 18V 14-Pin SOIC N T/R |
| AD8644AR-REEL7 | 制造商:Analog Devices 功能描述:OP Amp Quad GP R-R I/O 18V 14-Pin SOIC N T/R |
| AD8644ARU | 制造商:Analog Devices 功能描述:OP Amp Quad GP R-R I/O 18V 14-Pin TSSOP 制造商:Rochester Electronics LLC 功能描述:QUAD 18V LCD DRIVER - Bulk |
| AD8644ARU-REEL | 制造商:Analog Devices 功能描述:OP Amp Quad GP R-R I/O 18V 14-Pin TSSOP T/R 制造商:Rochester Electronics LLC 功能描述:QUAD 18V LCD DRIVER - Tape and Reel |
| AD8644ARUZ | 功能描述:IC OPAMP GP R-R 5.5MHZ 14TSSOP RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 放大器類型:通用 電路數(shù):4 輸出類型:滿擺幅 轉(zhuǎn)換速率:0.028 V/µs 增益帶寬積:105kHz -3db帶寬:- 電流 - 輸入偏壓:3nA 電壓 - 輸入偏移:100µV 電流 - 電源:3.3µA 電流 - 輸出 / 通道:12mA 電壓 - 電源，單路/雙路(±):2.7 V ~ 12 V，±1.35 V ~ 6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:14-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:14-TSSOP 包裝:剪切帶 (CT) 其它名稱:OP481GRUZ-REELCT |
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