ADIAD7793热电偶测量系统解决方案
2011-10-27
作者：ADI公司
</a>放大器" title="放大器">放大器" title="放大器">放大器能直接连接到ADC,增益设定为64,4.17Hz的噪音为40nV,工作电压2.7-5.25V, 主要用在热电偶测量,RTD测量,气体分析,工业过程控制,手持仪表,血液分析以及6位DVM等.本文介绍了AD7793主要特性,方框图, RTD和热电偶测量电路图以及采用AD7793 24位Sigma-Delta ADC完整的热电偶测量系统电路图和材料厂清单.
The AD7792/AD7793 are low power, low noise, complete analog front ends for high precision measurement applications. The AD7792/AD7793 contain a low noise 16-/24-bit Σ-Δ ADC with three differential analog inputs. The on-chip, low noise instrumentation amplifier means that signals of small amplitude can be interfaced directly to the ADC. With a gain setting of 64, the rms noise is 40 nV when the update rate equals 4.17 Hz.
The devices contain a precision low noise, low drift internal band gap reference and can accept an external differential reference. Other on-chip features include programmable excitation current sources, burnout currents, and a bias voltage generator. The bias voltage generator sets the common-mode voltage of a channel to AVDD/2.
The devices can be operated with either the internal clock or an external clock. The output data rate from the parts is software-programmable and can be varied from 4.17 Hz to 470 Hz.
The parts operate with a power supply from 2.7 V to 5.25 V. They consume a current of 400 μA typical and are housed in a 16-lead TSSOP package.
AD7793主要特性:
Up to 23 bits effective resolution
RMS noise
40 nV @ 4.17 Hz
85 nV @ 16.7 Hz
Current: 400 μA typical
Power-down: 1 μA maximum
Low noise programmable gain instrumentation amp
Band gap reference with 4 ppm/°C drift typical
Update rate: 4.17 Hz to 470 Hz
3 differential inputs
Internal clock oscillator
Simultaneous 50 Hz/60 Hz rejection
Programmable current sources
On-chip bias voltage generator
Burnout currents
Power supply: 2.7 V to 5.25 V
–40°C to +105°C temperature range
Independent interface power supply
16-lead TSSOP package
Interface
3-wire serial
SPI®, QSPI™, MICROWIRE™, and DSP compatible
Schmitt trigger on SCLK
AD7793应用:
Thermocouple measurements
RTD measurements
Thermistor measurements
Gas analysis
Industrial process control
Instrumentation
Portable instrumentation
Blood analysis
Smart transmitters
Liquid/gas chromatography
6-digit DVM
图1.AD7793方框图
图2.采用AD7792/3的RTD应用电路图
图3.采用AD7792/3的热电偶测量电路图
采用AD7793 24位Sigma-Delta ADC完整的热电偶测量系统
Complete Thermocouple Measurement System Using the AD7793 24-Bit Sigma-Delta ADC
The circuit, shown in Figure 4, is a complete thermocouple system based on the AD7793 24-bit sigma-delta ADC. The AD7793 is a low power, low noise, complete analog front end for high precision measurement applications. The device includes a PGA, internal reference, internal clock, and excitation currents, thereby greatly simplifying the thermocouple system design.
图4.带冷端补偿的热电偶测量系统电路图(简化电路图:所有的连接和去偶电容未标)
图5. 热电偶测量系统外形图
CN206热电偶测量系统材料清单见:
CN206热电偶测量系统材料清单.xls
详情请见:
http://www.analog.com/static/imported-files/circuit_notes/CN0206.pdf
和
http://www.analog.com/static/imported-files/data_sheets/AD7792_7793.pdf
The AD7792/AD7793 are low power, low noise, complete analog front ends for high precision measurement applications. The AD7792/AD7793 contain a low noise 16-/24-bit Σ-Δ ADC with three differential analog inputs. The on-chip, low noise instrumentation amplifier means that signals of small amplitude can be interfaced directly to the ADC. With a gain setting of 64, the rms noise is 40 nV when the update rate equals 4.17 Hz.
The devices contain a precision low noise, low drift internal band gap reference and can accept an external differential reference. Other on-chip features include programmable excitation current sources, burnout currents, and a bias voltage generator. The bias voltage generator sets the common-mode voltage of a channel to AVDD/2.
The devices can be operated with either the internal clock or an external clock. The output data rate from the parts is software-programmable and can be varied from 4.17 Hz to 470 Hz.
The parts operate with a power supply from 2.7 V to 5.25 V. They consume a current of 400 μA typical and are housed in a 16-lead TSSOP package.
AD7793主要特性:
Up to 23 bits effective resolution
RMS noise
40 nV @ 4.17 Hz
85 nV @ 16.7 Hz
Current: 400 μA typical
Power-down: 1 μA maximum
Low noise programmable gain instrumentation amp
Band gap reference with 4 ppm/°C drift typical
Update rate: 4.17 Hz to 470 Hz
3 differential inputs
Internal clock oscillator
Simultaneous 50 Hz/60 Hz rejection
Programmable current sources
On-chip bias voltage generator
Burnout currents
Power supply: 2.7 V to 5.25 V
–40°C to +105°C temperature range
Independent interface power supply
16-lead TSSOP package
Interface
3-wire serial
SPI®, QSPI™, MICROWIRE™, and DSP compatible
Schmitt trigger on SCLK
AD7793应用:
Thermocouple measurements
RTD measurements
Thermistor measurements
Gas analysis
Industrial process control
Instrumentation
Portable instrumentation
Blood analysis
Smart transmitters
Liquid/gas chromatography
6-digit DVM
图1.AD7793方框图
图2.采用AD7792/3的RTD应用电路图
图3.采用AD7792/3的热电偶测量电路图
采用AD7793 24位Sigma-Delta ADC完整的热电偶测量系统
Complete Thermocouple Measurement System Using the AD7793 24-Bit Sigma-Delta ADC
The circuit, shown in Figure 4, is a complete thermocouple system based on the AD7793 24-bit sigma-delta ADC. The AD7793 is a low power, low noise, complete analog front end for high precision measurement applications. The device includes a PGA, internal reference, internal clock, and excitation currents, thereby greatly simplifying the thermocouple system design.
图4.带冷端补偿的热电偶测量系统电路图(简化电路图:所有的连接和去偶电容未标)
图5. 热电偶测量系统外形图
CN206热电偶测量系统材料清单见:
CN206热电偶测量系统材料清单.xls详情请见:
http://www.analog.com/static/imported-files/circuit_notes/CN0206.pdf
和
http://www.analog.com/static/imported-files/data_sheets/AD7792_7793.pdf
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