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| 型號： | OPA621KP |
| 文件頁數(shù)： | 11/16頁 |
| 文件大?。?/td> | 193K |
| 代理商： | OPA621KP |
OPA621
11
recommended. Circuits using all surface mount components
with the OPA621AU (SO-8 package) will offer the best AC
performance. The parasitic package inductance and capaci-
tance for the SO-8 is lower than the both the Cerdip and
8-lead Plastic DIP.
6) Avoid overloading the output. Remember that output
current must be provided by the amplifier to drive its own
feedback network as well as to drive its load. Lowest
distortion is achieved with high impedance loads.
7) Don’t forget that these amplifiers use
±
5V supplies.
Although they will operate perfectly well with +5V and
–5.2V, use of
±
15V supplies will destroy the part.
8) Standard commercial test equipment has not been
designed to test devices in the OPA621’s speed range.
Benchtop op amp testers and ATE systems will require a
9) Terminate transmission line loads. Unterminated lines,
such as coaxial cable, can appear to the amplifier to be a
capacitive or inductive load. By terminating a transmission
line with its characteristic impedance, the amplifier’s load
then appears purely resistive.
10) Plug-in prototype boards and wire-wrap boards will not
be satisfactory. A clean layout using RF techniques is
essential; there are no shortcuts.
OFFSET VOLTAGE ADJUSTMENT
The OPA621’s input offset voltage is laser-trimmed and will
require no further adjustment for most applications. How-
ever, if additional adjustment is needed, the circuit in Figure
1 can be used without degrading offset drift with tempera-
ture. Avoid external adjustment whenever possible since
extraneous noise, such as power supply noise, can be
inadvertently coupled into the amplifier’s inverting input
terminal. Remember that additional offset errors can be
created by the amplifier’s input bias currents. Whenever
possible, match the impedance seen by both inputs as is
shown with R3. This will reduce input bias current errors to
the amplifier’s offset current, which is typically only 0.2
μ
A.
INPUT PROTECTION
Static damage has been well recognized for MOSFET
devices, but any semiconductor device deserves protection
from this potentially damaging source. The OPA621 incor-
porates on-chip ESD protection diodes as shown in Figure 2.
This eliminates the need for the user to add external
protection diodes, which can add capacitance and degrade
AC performance.
All pins on the OPA621 are internally protected from ESD
by means of a pair of back-to-back reverse-biased diodes to
either power supply as shown. These diodes will begin to
conduct when the input voltage exceeds either power supply
by about 0.7V. This situation can occur with loss of the
amplifier’s power supplies while a signal source is still
present. The diodes can typically withstand a continuous
current of 30mA without destruction. To insure long term
reliability, however, diode current should be externally
limited to 10mA or so whenever possible.
The internal protection diodes are designed to withstand
2.5kV (using Human Body Model) and will provide
adequate ESD protection for most normal handling proce-
dures. However, static damage can cause subtle changes in
amplifier input characteristics without necessarily destroy-
ing the device. In precision operational amplifiers, this may
cause a noticeable degradation of offset voltage and drift.
Therefore, static protection is strongly recommended when
handling the OPA621.
OUTPUT DRIVE CAPABILITY
The OPA621’s design uses large output devices and has
been optimized to drive 50
and 75
resistive loads. The
device can easily drive 6Vp-p into a 50
load. This high-
output drive capability makes the OPA621 an ideal choice
for a wide range of RF, IF, and video applications. In many
cases, additional buffer amplifiers are unneeded.
Internal current-limiting circuitry limits output current to
about 150mA at 25
°
C. This prevents destruction from
accidental shorts to common and eliminates the need for
external current-limiting circuitry. Although the device can
withstand momentary shorts to either power supply, it is not
recommended.
Many demanding high-speed applications such as ADC/
DAC buffers require op amps with low wideband output
impedance. For example, low output impedance is essential
* R
is optional and can be used to cancel offset errors due to input bias
currents.
FIGURE 1. Offset Voltage Trim.
ESD Protection diodes internally
connected to all pins.
External
Pin
+V
CC
–V
CC
Internal
Circuitry
FIGURE 2. Internal ESD Protection.
R
2
OPA621
*R = R || R
2
R
1
R
Trim
+V
CC
–V
CC
20k
V or Ground
Output Trim Range +V ( R ) to –V ( R )
R
Trim
R
Trim
47k
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
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| OPA621KP-1 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| OPA621KU | 制造商:BB 制造商全稱:BB 功能描述:Wideband Precision OPERATIONAL AMPLIFIER |
| OPA622 | 制造商:BB 制造商全稱:BB 功能描述:Wide-Bandwidth OPERATIONAL AMPLIFIER |
| OPA622AP | 制造商:BB 制造商全稱:BB 功能描述:Wide-Bandwidth OPERATIONAL AMPLIFIER |
| OPA622AU | 制造商:BB 制造商全稱:BB 功能描述:Wide-Bandwidth OPERATIONAL AMPLIFIER |
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