AN-607: Selecting a Low Bandwidth (<15 kSPS) Sigma-Delta ADC
Introduction
Analog Devices, Inc., has a wide range of low bandwidth, high resolution Σ-Δ ADCs. Along with the ADC, these devices contain current sources, a multiplexer, a PGA, and analog input buffers on-board. This application note identifies some of the applications in which the ADCs are used and also identifies the most suitable ADCs for each application.
Number Of Bits
16-Bit: AD7705, AD7706, AD7707, AD7708, AD7709, AD7715, AD7788, AD7790, AD7792, AD7795, AD7796, AD7798
24-Bit: AD7710, AD7711, AD7711A, AD7712, AD7713, AD7714, AD7718, AD7719, AD7730, AD7730L, AD7731, AD7732, AD7734, AD7738, AD7739, AD7782, AD7783, AD7787, AD7789, AD7791, AD7793, AD7794, AD7797, AD7799
Multichannel Applications
High Throughput: AD7731, AD7734, AD7738, AD7739
Low Throughput: AD7708/AD7718, AD7714, AD7794/AD7795s
Temperature Measurement
For thermal diode and RTD applications, current sources are required.
Thermocouple: AD7714, AD7719, AD7792/AD7793, AD7794/AD7795
Thermal Diode: AD7709
RTD: AD7711, AD7719, AD7783, AD7792/AD7793, AD7794/AD7795
Pressure Measurement
Requirements: Low level differential analog inputs with a high level differential reference input for ratiometric operation. Optional features include an auxiliary ADC that can be used for temperature compensation.
AD7710, AD7714, AD7719, AD7730, AD7798/AD7799
Weigh Scale Measurement
Requirements: Low level differential analog inputs with a high level differential reference input for ratiometric operation. Optional features include an auxiliary ADC that can be used for temperature compensation, fast-step, ac excitation, a reference detect circuit, and increased filter rejection in the out-of-band region.
AD7714, AD7719, AD7730, AD7730L, AD7796/AD7797, AD7798/AD7799
Low Power
AD7705/AD7706, AD7714, AD7715, AD7719, AD7787, AD7788/AD7789, AD7790, AD7791, AD7792/AD7793, AD7794/AD7795, AD7796/AD7797, AD7798/AD7799
High Analog Input Voltages (±10 V)
AD7707, AD7712, AD7732, AD7734
Rail-To-Rail On-Chip Buffers
AD7708/AD7718, AD7709, AD7719, AD7782, AD7783, AD7787, AD7790, AD7791
Bipolar Inputs (±2.5 V)
Pin Configurable
| Part No. | Bits | p-p Resolution @ Max Range (Bits) | p-p Resolution @ Data Rate (Hz) | AIN Channels | On-Chip PGA | On-Chip AIN Buffer | On-Chip Current Source | AVDD/DVDD (V) | Power Supply Current (mA) | Price ($/1k) | Comments |
| AD7701 | 16 | 16 | 4000 | 1 | 5 | 5 | 15.70 | 10 Hz bandwidth | |||
| AD7703 | 20 | 17 | 4000 | 1 | 5 | 5 | 13.26 | 10 Hz bandwidth | |||
| AD7705 | 16 | 16 | 60 | 2 | Y | Y | 3/5 | 0.3 | 4.12 | ||
| AD7706 | 16 | 16 | 60 | 3 | Y | Y | 3/5 | 0.3 | 4.12 | ||
| AD7707 | 16 | 16 | 60 | 3 | Y | Y | 3/5 | 0.28 | 4.46 | ||
| AD7708 | 16 | 16 | 20 | 10 | Y | Y | 3/5 | 1.28 | 3.98 | ||
| AD7709 | 16 | 16 | 20 | 4 | Y | Y | Y | 3/5 | 1.25 | 3.89 | |
| AD7710 | 24 | 17.5 | 60 | 2 | Y | 5 | 5 | 14.45 | |||
| AD7711 | 24 | 17.5 | 60 | 2 | Y | Y | 5 | 5 | 15.30 | Two current sources | |
| AD7711A | 24 | 17.5 | 60 | 2 | Y | Y | 5 | 5 | 15.30 | One current source | |
| AD7712 | 24 | 17.5 | 60 | 2 | Y | 5 | 5 | 13.20 | |||
| AD7713 | 24 | 16 | 20 | 3 | Y | Y | 5 | 0.7 | 16.15 | ||
| AD7714 | 24 | 17.5 | 60 | 5 | Y | Y | 3/5 | 0.35 | 8.28 | ||
| AD7715 | 16 | 16 | 60 | 1 | Y | Y | 3/5 | 0.35 | 5.65 | ||
| AD7718 | 24 | 18.5 | 20 | 10 | Y | Y | 3/5 | 1.28 | 5.24 | ||
| AD7719 | 24 | 18.5 | 20 | 5 | Y | Y | Y | 3/5 | 1.5 | 8.76 | Dual ADC |
| AD7730 | 24 | 17 | 200 | 2 | Y | Y | AVDD: 5 DVDD: 3/5 |
13 | 11.60 | Weigh scale | |
| AD7730L | 24 | 17 | 200 | 2 | Y | Y | AVDD: 5 DVDD: 3/5 |
13 | 9.55 | Weigh scale | |
| AD7731 | 24 | 17 | 800 | 5 | Y | Y | AVDD: 5 DVDD: 3/5 |
13.5 | 9.86 | ||
| AD7732 | 24 | 16 | 2000 | 2 | Y | Y | AVDD: 5 DVDD: 3/5 |
18 | 8.50 | Fast channel switching | |
| AD7734 | 24 | 16 | 2000 | 4 | Y | Y | AVDD: 5 DVDD: 3/5 |
18 | 8.50 | Fast channel switching | |
| AD7738 | 24 | 16 | 8500 | 8 | Y | Y | AVDD: 5 DVDD: 3/5 |
18 | 7.77 | Fast channel switching | |
| AD7739 | 24 | 16 | 4000 | 8 | Y | Y | AVDD: 5 DVDD: 3/5 |
14 | 7.65 | Fast channel switching | |
| AD7782 | 24 | 18.5 | 20 | 2 | Y | Y | 3/5 | 1.3 | 4.25 | Read-only | |
| AD7783 | 24 | 18.5 | 20 | 1 | Y | 3/5 | 1.3 | 4.25 | Read-only | ||
| AD7787 | 24 | 19 | 16.6 | 2 | Y | 3/5 | 0.13 | 3.80 | Low power | ||
| AD7788 | 16 | 16 | 16.6 | 1 | 3/5 | 0.065 | 1.99 | Low power | |||
| AD7789 | 24 | 19 | 16.6 | 1 | 3/5 | 0.065 | 2.95 | Low power | |||
| AD7790 | 16 | 16 | 16.6 | 1 | Y | 3/5 | 0.13 | 2.96 | Low power | ||
| AD7791 | 24 | 19 | 16.6 | 1 | Y | 3/5 | 0.13 | 3.83 | Low power | ||
| AD7792 | 16 | 16 | 16.6 | 3 | Y | Y | Y | 3/5 | 0.40 | 3.99 | On-chip reference |
| AD7793 | 24 | 19 | 16.6 | 3 | Y | Y | Y | 3/5 | 0.40 | 5.10 | On-chip reference |
| AD7794 | 24 | 19 | 16.6 | 6 | Y | Y | Y | 3/5 | 0.40 | 4.80 | High channel count |
| AD7795 | 16 | 16 | 16.6 | 6 | Y | Y | Y | 3/5 | 0.40 | 4.40 | High channel count |
| AD7796 | 16 | 15.5 | 16.6 | 1 | Y | Y | 3/5 | 0.25 | 2.75 | Weigh scale | |
| AD7797 | 24 | 15.5 | 16.6 | 1 | Y | Y | 3/5 | 0.25 | 3.35 | Weigh scale | |
| AD7798 | 16 | 16 | 16.6 | 3 | Y | Y | 3/5 | 0.30 | 3.80 | Weigh scale/pressure | |
| AD7799 | 24 | 19 | 16.6 | 3 | Y | Y | 3/5 | 0.38 | 4.35 | Weigh scale/pressure |
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