AD7711 CMOS, 24-Bit Sigma-Delta, Signal Conditioning ADC with Matched RTD Excitation Currents

The AD7711 is a complete analog front end for low frequency measurement applications. The device accepts low level signals directly from a transducer and outputs a serial digital word. It employs a sigma-delta conversion technique to realize up to 24 bits of no missing codes performance. The input signal is applied to a proprietary programmable gain front end based around an analog modulator. The modulator output is processed by an on-chip digital filter. The first notch of this digital filter can be programmed via the on-chip control register allowing adjustment of the filter cutoff and settling time.

The part features one differential analog input and one single ended analog input as well as a differential reference input. Normally, one of the input channels will be used as the main channel with the second channel used as an auxiliary input to periodically measure a second voltage. It can be operated from a single supply (by tying the VSS pin to AGND) provided that the input signals on the analog inputs are more positive than -30 mV. By taking the VSS pin negative, the part can convert signals down to -VREF on its inputs. The part provides two current sources that can be used to provide excitation in three-wire and four-wire RTD configurations. The AD7711 thus performs all signal conditioning and conversion for a single or dual channel system.

The AD7711 is ideal for use in smart, microcontroller based systems. Gain settings, signal polarity, input channel selection and RTD current control can be configured in software using the bidirectional serial port. The AD7711 contains self-measurement calibration, system calibration and background calibration options and also allows the user to read and write the on-chip calibration registers.

CMOS construction ensures low power dissipation, and a software programmable power-down mode reduces the standby power consumption to only 7 mW typical. The part is available in a 24-pin, 0.3 inch wide, plastic and hermetic dual-in-line package (DIP) as well as a 24-lead small outline (SOIC) package.

Features and Benefits
  • Charge-Balancing ADC
    24 Bits, No Missing Codes
    ±0.0015% Nonlinearity
  • 2-Channel Programmable Gain Front End
    Gains from 1 to 128
    1 Differential Input
    1 Single-Ended Input
  • Low-Pass Filter with Programmable Filter Cutoffs
  • Ability to Read/Write Calibration Coefficients
  • RTD Excitation Current Sources
  • Bidirectional Microcontroller Serial Interface
  • Internal/External Reference Option
  • Single- or Dual-Supply Operation
  • Low Power (25 mW typ) with Power-Down Mode (7 mW typ)
Analog to Digital Converters
Data Sheets
Documentnote
AD7711: LC2MOS Signal Conditioning ADC with RTD Excitation Currents Data Sheet (Rev. G)PDF 1129 kB
Application Notes
Documentnote
AN-931: Understanding PulSAR ADC Support Circuitry (Rev. 0)PDF 299 kB
AN-202: An IC Amplifier User’s Guide to Decoupling, Grounding, and Making Things Go Right for a Change (Rev. B)PDF 76.97 K
AN-389: Using Sigma-Delta Converters-Part 2PDF 590 kB
AN-388: Using Sigma-Delta Converters-Part 1PDF 590 kB
AN-311: How to Reliably Protect CMOS Circuits Against Power Supply OvervoltagingPDF 217 kB
AN-607: Selecting a Low Bandwidth (<15 kSPS) Sigma-Delta ADC (Rev. E)PDF 222 kB
AN-615: Peak-to-Peak Resolution Versus Effective Resolution (Rev. 0)PDF 70 kB
AN-397: Electrically Induced Damage to Standard Linear Integrated Circuits:PDF 149 kB
AN-283: Sigma-Delta ADCs and DACsPDF 1699 kB
AN-553: Adjusting the Calibration Coefficients on the AD771X Family of ADCsPDF 221 kB
AN-406: Using the AD771X Family of 24-Bit Sigma-Delta A/D ConvertersPDF 187 kB
AN-366: Evaluation Board for the AD7711 24-Bit Sigma-Delta ADCPDF 454 kB
Order Information
Part NumberPackagePacking QtyTemp RangePrice 100-499Price 1000+RoHS
AD7711AAR Production24 ld SOIC - WideOTH 31-40 to 85C00N
AD7711AARZ Production24 ld SOIC - WideOTH 31-40 to 85C21.6718.43Y
AD7711ANZ Production24 ld PDIPOTH 15-40 to 85C26.2120.27Y
AD7711AQ ProductionCERDIP GLASS SEALOTH 15-40 to 85C00N
AD7711AR Production24 ld SOIC - WideOTH 31-40 to 85C00N
AD7711AR-REEL7 Production24 ld SOIC - WideREEL 400-40 to 85C00N
AD7711ARZ Production24 ld SOIC - WideOTH 31-40 to 85C23.8318.43Y
AD7711ARZ-REEL Production24 ld SOIC - WideREEL 1000-40 to 85C018.43Y
AD7711ARZ-REEL7 Production24 ld SOIC - WideREEL 400-40 to 85C018.43Y
AD7711ASQ ProductionCERDIP GLASS SEALOTH 15-55 to 125C83.4270.93N
Reference Materials
AD7711: LC2MOS Signal Conditioning ADC with RTD Excitation Currents Data Sheet (Rev. G) ad7711
AD7711参考代码 ad7711
AN-931: Understanding PulSAR ADC Support Circuitry (Rev. 0) ad7476
AN-202: An IC Amplifier User’s Guide to Decoupling, Grounding, and Making Things Go Right for a Change (Rev. B) ad7715
AN-389: Using Sigma-Delta Converters-Part 2 ad7715
AN-388: Using Sigma-Delta Converters-Part 1 ad7715
AN-397: 标准线性集成电路的电诱发损坏 (Rev. 0) ad7715
AN-615: 峰峰值分辨率与有效分辨率 (Rev. 0) ad7715
AN-607: 选择低带宽(<15kSPS)Σ-Δ型ADC (Rev. E) ad7701
AN-202: IC放大器用户指南：去耦、接地及其他一些要点 (Rev. 0) ad8021
AN-931: 了解PulSAR ADC支持电路 (Rev. 0) ad7476
AN-311: How to Reliably Protect CMOS Circuits Against Power Supply Overvoltaging ad1674
AN-607: Selecting a Low Bandwidth (<15 kSPS) Sigma-Delta ADC (Rev. E) ad7701
AN-615: Peak-to-Peak Resolution Versus Effective Resolution (Rev. 0) ad7715
AN-397: Electrically Induced Damage to Standard Linear Integrated Circuits: ad7715
AN-311: 如何切实有效地保护CMOS电路不受电源过压影响 (Rev. 0) adg406
AN-389: 使用Σ-Δ转换器—第二部分[中文版] (Rev. 0) ad7715
AN-388: 使用Σ-Δ转换器—第一部分[中文版] (Rev. 0) ad7715
AN-283: Σ-Δ型ADC和DAC[中文版] (Rev. 0) ad74111
AN-283: Sigma-Delta ADCs and DACs ad7715
AN-553: Adjusting the Calibration Coefficients on the AD771X Family of ADCs ad7710
AN-406: Using the AD771X Family of 24-Bit Sigma-Delta A/D Converters ad7710
AN-366: Evaluation Board for the AD7711 24-Bit Sigma-Delta ADC ad7711
MS-2210：高速ADC的电源设计 ad9861
Part 2: Circuit Suggestions Using Features and Functionality of New Sigma-Delta ad7715
Part 1: Circuit Suggestions Using Features and Functionality of New Sigma-Delta ad7715
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