参数资料
| 型号： | AD7713AN |
| 厂商： | Analog Devices Inc |
| 文件页数： | 17/28页 |
| 文件大小： | 0K |
| 描述： | IC ADC 24BIT SIGMA-DELTA 24-DIP |
| 产品变化通告： | Product Discontinuance 27/Oct/2011 |
| 标准包装： | 15 |
| 位数： | 24 |
| 采样率（每秒）： | 205 |
| 数据接口： | 串行 |
| 转换器数目： | 1 |
| 功率耗散（最大）： | 5.5mW |
| 电压电源： | 模拟和数字 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 通孔 |
| 封装/外壳： | 24-DIP（0.300"，7.62mm） |
| 供应商设备封装： | 24-PDIP |
| 包装： | 管件 |
| 输入数目和类型： | 1 个单端，单极；1 个差分，单极；1 个差分，双极 |
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REV. D
–24–
AD7713
SYNC
RFS
TFS
A0
SDATA
SCLK
MODE
PC0
PC1
PC2
PC3
MISO
MOSI
68HC11
AD7713
DRDY
SS
SCK
DVDD
Figure 18. AD7713 to 68HC11 Interface
APPLICATIONS
4-Wire RTD Configurations
Figure 19 shows a 4-wire RTD application where the RTD
transducer is interfaced directly to the AD7713. In the 4-wire
configuration, there are no errors associated with lead resis-
tances as no current flows in the measurement leads connected
to AIN1(+) and AIN1(–). One of the RTD current sources is
used to provide the excitation current for the RTD. A common
nominal resistance value for the RTD is 100
and, therefore, the
RTD will generate a 20 mV signal, which can be handled directly
by the analog input of the AD7713. In the circuit shown, the
second RTD excitation current is used to generate the reference
voltage for the AD7713. This reference voltage is developed
across RREF and applied to the differential reference inputs. For
the nominal reference voltage of 2.5 V, RREF is 12.5 k
. This
scheme ensures that the analog input voltage span remains
ratiometric to the reference voltage. Any errors in the analog
input voltage due to the temperature drift of the RTD current
source is compensated for by the variation in the reference volt-
age. The typical matching between the two RTD current sources
is less than 3 ppm/
°C.
AIN1(+)
AIN1(–)
AVDD
AGND
DGND
A = 1 – 128
AD7713
RTD1
REF IN(+)
REF IN(–)
RTD2
200 A
5V
RREF
INTERNAL
CIRCUITRY
DVDD
PGA
200 A
RTD
Figure 19. 4-Wire RTD Application with the AD7713
3-Wire RTD Configurations
Figure 20 shows a 3-wire RTD configuration using the AD7713.
In the 3-wire configuration, the lead resistances will result in
errors if only one current source is used as the 200
A will flow
through RL1 developing a voltage error between AIN1(+) and
AIN1(–). In the scheme outlined below, the second RTD cur-
rent source is used to compensate for the error introduced by
the 200
A flowing through RL1. The second RTD current
flows through RL2. Assuming RL1 and RL2 are equal (the leads
would normally be of the same material and of equal length) and
RTD1 and RTD2 match, then the error voltage across RL2 equals
the error voltage across RL1, and no error voltage is developed
between AIN1(+) and AIN1(–). Twice the voltage is developed
across RL3 but since this is a common-mode voltage, it will not
introduce any errors. The reference voltage is derived from one
of the current sources. This gives all the benefits of eliminating
RTD temperature coefficient errors as outlined in Figure 19.
The voltage on either RTD input can go to within 2 V of the
AVDD supply. The circuit is shown for a 2.5 V reference.
AIN(+)
AIN(–)
AVDD DVDD
AGND
DGND
A = 1 – 128
AD7713
RTD1
RTD2
12.5k
INTERNAL
CIRCUITRY
REF IN(+)
REF IN(–)
RL1
RL2
RL3
PGA
RTD
200 A
Figure 20. 3-Wire RTD Application with the AD7713
4–20 mA Loop
The AD7713’s high level input can be used to measure the
current in 4–20 mA loop applications as shown in Figure 21. In
this case, the system calibration capabilities of the AD7713 can
be used to remove the offset caused by the 4 mA flowing through
the 500
resistor. The AD7713 can handle an input span as
low as 3.2
VREF (= 8 V with a VREF of 2.5 V) even though the
nominal input voltage range for the input is 10 V. Therefore,
the full span of the ADC can be used for measuring the current
between 4 and 20 mA.
REF IN(+)
AIN1(+)
AIN1(–)
AIN3
AGND
DGND
A = 1 – 128
REF IN(–)
AD7713
4–20mA
LOOP
ANALOG 5V SUPPLY
500
VOLTAGE
ATTENUATION
AVDD
DVDD
INTERNAL
CIRCUITRY
MUX
PGA
1 A
Figure 21. 4-20 mA Measurement Using the AD7713
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相关代理商/技术参数 |
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| AD7713ANZ | 功能描述:IC ADC 24BIT SIGMA-DELTA 24-DIP RoHS:是 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 其它有关文件:TSA1204 View All Specifications 标准包装:1 系列:- 位数:12 采样率（每秒）:20M 数据接口:并联 转换器数目:2 功率耗散（最大）:155mW 电压电源:模拟和数字 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-TQFP 供应商设备封装:48-TQFP（7x7） 包装:Digi-Reel® 输入数目和类型:4 个单端，单极；2 个差分，单极 产品目录页面:1156 (CN2011-ZH PDF) 其它名称:497-5435-6 |
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