Download ADI AD5933高精度阻抗测量解决方案CN0217

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ADI AD5933 高精度阻抗测量解决方案 CN0217
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ADI AD5933 高精度阻抗测量解决方案 CN0217
ADI AD5933 高精度阻抗测量解决方案 CN0217
关键字：工业控制,测试仪表, 阻抗测量
ADI 公司的高精度阻抗测量解决方案 CN0217 采用 12 位阻抗转换器 AD5933/AD5934. AD5933
是 1MSPS 的 12 位 ADC,而 AD5934 是 250KSPS 的 12 位 ADC,内部集成了温度传感器(±2°C),
系统精度 0.5%,工作电压 2.7V-5.5V,图 1 的电路优化了信号链,其阻抗测量范围从低欧姆数到
几百 kΩ,主要用在电化学分析,生物阻抗分析,复数阻抗分析,生物和汽车传感器,接近式检测,
非破坏性检测,以及材料特性分析和燃料/电池状态监视等.本文介绍了 AD5933 主要特性, 功
能方框图, 病毒株血样本测量框图和 AD5933 评估板主要特性,电路图与材料清单.
The AD5933 and AD5934 are high precision impedance converter system solutions that
combine an on-chip programmable frequency generator with a 12-bit, 1 MSPS (AD5933)
or 250 kSPS (AD5934) analog-to-digital converter (ADC). The tunable frequency
generator allows an external complex impedance to be excited with a known frequency.
The circuit shown in Figure 1 yields accurate impedance measurements extending from
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the low ohm range to several hundred kΩ and also optimizes the overall accuracy of
the AD5933/AD5934.
图 1.高精度阻抗测量优化信号链的电路图
The AD5http://doc.xuehai.net/bbbc5952521101746899a706b.html933 is a high precision
impedance converter system solution that combines an on-board frequency generator
with a 12-bit, 1 MSPS, analog-to-digital converter (ADC). The frequency generator
allows an external complex impedance to be excited with a known frequency. The
response signal from the impedance is sampled by the on-board ADC and a discrete
Fourier transform (DFT) is processed by an on-board DSP engine. The DFT algorithm
returns a real (R) and imaginary (I) data-word at
each output frequency.
Once calibrated, the magnitude of the impedance and relative phase of the impedance
at each frequency point along the sweep is easily calculated. This is done off chip
using the real and imaginary register contents, which can be read from the serial
I2C interface.
A similar device, also available from Analog Devices, Inc., is the AD5934, a 2.7 V
to
5.5
V,
250
kSPS,
12-bit
impedance
converter,
http://doc.xuehai.net/bbbc5952521101746899a706b.htmlwith an internal temperature
sensor and is packaged in a 16-lead SSOP.
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AD5933 主要特性:
Programmable output peak-to-peak excitation voltage to a maximum frequency of 100
kHz
Programmable frequency sweep capability with serial I2C interface
Frequency resolution of 27 bits (
Impedance measurement range from 1 kΩ to 10 MΩ
Capable of measuring of 100 Ω to 1 kΩ with additional circuitry
Internal temperature sensor (±2℃)
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Internal system clock option
Phase measurement capability
System accuracy of 0.5%
2.7 V to 5.5 V power supply operation
Temperature range: ?40℃ to
16-lead SSOP package
AD5933 应用:
Electrochemical analysis
125℃
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Bioelectrical
imhttp://doc.xuehai.net/bbbc5952521101746899a706b.htmlpedance
analysis
Impedance spectroscopy
Complex impedance measurement
Corrosion monitoring and protection equipment
Biomedical and automotive sensors
Proximity sensing
Nondestructive testing
Material property analysis
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Fuel/battery cell condition monitoring
图 2. AD5933 功能方框图
图 3. 采用 AD5933 的病毒株血样本测量框图
AD5933 评估板
This document describes the evaluation board for the AD5933 and the application
software developed to interface to the device.
The AD5933 is a high precision impedance converter system that combines an on-board
frequency generator with a 12-bit, 1 MSPS ADC. The frequency generator allows an
external complex impedance to be excited with a known frequency. The response signal
from the impedahttp://doc.xuehai.net/bbbc5952521101746899a706b.htmlnce is sampled
by the on-board ADC, and the DFT is processed by an on-board DSP engine at each
excitation frequency. The AD5933 also contains an internal temperature sensor with
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13-bit resolution and operates from a 2.7 V to
5.5 V supply.
Other on-board components include an ADR423 3.0 V reference that acts as a stable
supply voltage for the separate analog and digital sections of the device and an
ADP3303 ultrahigh precision regulator that acts as a supply to the on-board universal
serial bus controller, which interfaces to the AD5933. The user can power the entire
circuitry from the USB port of a computer. The evaluation board also has a high
performance, trimmed, 16 MHz, surface-mount crystal that can act as a system clock
for the AD5933, if required.
The various link options available on the evaluation board are explained in Table
2.
Interfacing
to
the
AD5933
is
through
microchttp://doc.xuehai.net/bbbc5952521101746899a706b.htmlontroller,
a
USB
which
generates the IC signals necessary to communicate with the AD5933.The user interfaces
to the USB microcontroller through a Visual Basic? graphic user interface located
on and run from the user PC. More information on the AD5933 is available from Analog
Devices, Inc., at www.analog.com and should be consulted when using the evaluation
board.
AD5933 评估板主要特性:
Full-featured evaluation board for the AD5933
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Graphic user interface software with frequency sweep capability for board control
and data analysis
Various power supply linking options
Standalone capability with serial IC loading from on-board microcontroller
Selectable system clock options, including internal RC oscillator or on-board 16 MHz
crystal
AD5933 评估板应用:
Electrochemical analysis
Impedance spectroscopy://doc.xuehai.net/bbbc5952521101746899a706b.html
22
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Complex impedance measurement
Corrosion monitoring and protection equipment
Biomedical and automotive sensors
Proximity sensing
图 4.AD5933 评估板方框图
图 5. EVAL-CN0217-EBIZ 电路图(1)
图 6. EVAL-CN0217-EBIZ 电路图(2)
图 7. EVAL-CN0217-EBIZ 电路图(3)
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