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參數資料
| 型號： | AD8628 |
| 廠商： | Analog Devices, Inc. |
| 元件分類： | 運動控制電子 |
| 英文描述： | Zero-Drift, Single-Supply, Rail-to-Rail Input/Output Low Noise Operational Amplifier |
| 中文描述： | 零漂移，單電源，軌到軌輸入/輸出低噪聲運算放大器 |
| 文件頁數： | 18/20頁 |
| 文件大?。?/td> | 476K |
| 代理商： | AD8628 |
AD8628/AD8629
PRECISION CURRENT SHUNTS
A precision shunt current sensor benefits from the unique
attributes of auto-zero amplifiers when used in a differencing
configuration (Figure 63). Shunt current sensors are used in
precision current sources for feedback control systems. They are
also used in a variety of other applications, including battery
fuel gauging, laser diode power measurement and control,
torque feedback controls in electric power steering, and
precision power metering.
Rev. C | Page 18 of 20
R
S
0.1
SUPPLY
I
R
L
100
100k
C
5V
100
100k
C
e = 1,000 R
S
I
100mV/mA
AD8628
0
Figure 63. Low-Side Current Sensing
In such applications, it is desirable to use a shunt with very low
resistance to minimize the series voltage drop; this minimizes
wasted power and allows the measurement of high currents
without saving power. A typical shunt might be 0.1 . At
measured current values of 1 A, the shunt’s output signal is
hundreds of mV, or even V, and amplifier error sources are not
critical. However, at low measured current values in the 1 mA
range, the 100 μV output voltage of the shunt demands a very
low offset voltage and drift to maintain absolute accuracy. Low
input bias currents are also needed, so that injected bias current
does not become a significant percentage of the measured
current. High open-loop gain, CMRR, and PSRR all help to
maintain the overall circuit accuracy. As long as the rate of
change of the current is not too fast, an auto-zero amplifier can
be used with excellent results.
OUTPUT AMPLIFIER FOR HIGH PRECISION DACs
The AD8628/AD8629 are used as output amplifiers for a 16-bit
high precision DAC in a unipolar configuration. In this case, the
selected op amp needs to have very low offset voltage (the DAC
LSB is 38 μV when operated with a 2.5 V reference) to eliminate
the need for output offset trims. Input bias current (typically a
few tens of picoamperes) must also be very low, because it
generates an additional zero code error when multiplied by the
DAC output impedance (approximately 6 k).
Rail-to-rail input and output provide full-scale output with very
little error. Output impedance of the DAC is constant and code-
independent, but the high input impedance of the AD8628/
AD8629 minimizes gain errors. The amplifiers’ wide bandwidth
also serves well in this case. The amplifiers, with settling time of
1 μs, add another time constant to the system, increasing the
settling time of the output. The settling time of the AD5541 is
1 μs. The combined settling time is approximately 1.4 μs, as can
be derived from the following equation:
(
)
(
)
(
)
2
2
8628
AD
t
DAC
t
TOTAL
t
S
S
S
+
=
0
AD5541/AD5542
AD8628
DGND
*AD5542 ONLY
V
DD
REF(REF*)
REFS*
OUT
SCLK
DIN
CS
AGND
5V
2.5V
UNIPOLAR
OUTPUT
LDAC*
0.1
μ
F
10
μ
F
0.1
μ
F
SERIAL
INTERFACE
Figure 64. AD8628 Used as an Output Amplifier
相關PDF資料 |
PDF描述 |
|---|---|
| AD8629ARZ1 | Zero-Drift, Single-Supply, Rail-to-Rail Input/Output Operational Amplifier |
| AD8628AUJZ-REEL | ER 2C 2#16S PIN PLUG |
| AD8628AUJZ-REEL7 | Circular Connector; No. of Contacts:2; Series:; Body Material:Aluminum Alloy; Connecting Termination:Solder; Connector Shell Size:10SL; Circular Contact Gender:Pin; Circular Shell Style:Straight Plug; Insert Arrangement:10SL-4 RoHS Compliant: No |
| AD8628ARTZ-REEL7 | Zero-Drift, Single-Supply, Rail-to-Rail Input/Output Operational Amplifier |
| AD8629ARMZ-REEL | Zero-Drift, Single-Supply, Rail-to-Rail Input/Output Operational Amplifier |
相關代理商/技術參數 |
參數描述 |
|---|---|
| AD8628_05 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Zero-Drift, Single-Supply, Rail-to-Rail Input/Output Operational Amplifier |
| AD8628_08 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Zero-Drift, Single-Supply, Rail-to-Rail Input/Output Operational Amplifier |
| AD8628AR | 制造商:Analog Devices 功能描述:SP Amp Chopper Stabilization Single R-R I/O ±2.5V/5V 8-Pin SOIC N Tube 制造商:Analog Devices 功能描述:IC SM OP-AMP Z-DRIFT RRI/O |
| AD8628AR-REEL | 制造商:Analog Devices 功能描述:SP Amp Chopper Stabilization Single R-R I/O ±2.5V/5V 8-Pin SOIC N T/R |
| AD8628AR-REEL7 | 制造商:Analog Devices 功能描述:SP Amp Chopper Stabilization Single R-R I/O ±2.5V/5V 8-Pin SOIC N T/R |
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