AD7124-8 8-Channel, Low Noise, Low Power, 24-Bit, Sigma-Delta ADC with PGA and Reference

The AD7124-8 is a low power, low noise, completely integrated analog front end for high precision measurement applications. The device contains a low noise, 24-bit Σ-Δ analog-to-digital converter (ADC), and can be configured to have 8 differential inputs or 15 single-ended or pseudo differential inputs. The onchip low gain stage ensures that signals of small amplitude can be interfaced directly to the ADC.

One of the major advantages of the AD7124-8 is that it gives the user the flexibility to employ one of three integrated power modes. The current consumption, range of output data rates, and rms noise can be tailored with the power mode selected. The device also offers a multitude of filter options, ensuring that the user has the highest degree of flexibility. The AD7124-8 can achieve simultaneous 50 Hz and 60 Hz rejection when operating at an output data rate of 25 SPS (single cycle settling), with rejection in excess of 80 dB achieved at lower output data rates.

The AD7124-8 establishes the highest degree of signal chain integration. The device contains a precision, low noise, low drift internal band gap reference and accepts an external differential reference, which can be internally buffered. Other key integrated features include programmable low drift excitation current sources, burnout currents, and a bias voltage generator, which sets the common-mode voltage of a channel to AVDD/2. The low-side power switch enables the user to power down bridge sensors between conversions, ensuring the absolute minimal power consumption of the system. The device also allows the user the option of operating with either an internal clock or an external clock.

The integrated channel sequencer allows several channels to be enabled simultaneously, and the AD7124-8 sequentially converts on each enabled channel, simplifying communication with the device. As many as 16 channels can be enabled at any time, a channel being defined as an analog input or a diagnostic such as a power supply check or a reference check. This unique feature allows diagnostics to be interleaved with conversions. The AD7124-8 also supports per channel configuration. The device allows eight configurations or setups. Each configuration consists of gain, filter type, output data rate, buffering, and reference source. The user can assign any of these setups on a channel by channel basis.

The AD7124-8 also has extensive diagnostic functionality integrated as part of its comprehensive feature set. These diagnostics include a cyclic redundancy check (CRC), signal chain checks, and serial interface checks, which lead to a more robust solution. These diagnostics reduce the need for external components to implement diagnostics, resulting in reduced board space needs, reduced design cycle times, and cost savings. The failure modes effects and diagnostic analysis (FMEDA) of a typical application has shown a safe failure fraction (SFF) greater than 90% according to IEC 61508.

The device operates with a single analog power supply from 2.7 V to 3.6 V or a dual 1.8 V power supply. The digital supply has a range of 1.65 V to 3.6 V. It is specified for a temperature range of −40°C to +125°C. The AD7124-8 is housed in a 32-lead LFCSP package.

Note that, throughout this data sheet, multifunction pins, such as DOUT/RDY, are referred to either by the entire pin name or by a single function of the pin, for example, RDY, when only that function is relevant.

Applications

Features and Benefits
  • 3 power modes
  • RMS noise
    • Low power: 24 nV rms at 1.17 SPS, gain = 128 (255 µA typical)
    • Mid power: 20 nV rms at 2.34 SPS, gain = 128 (355 µA typical)
    • Full power: 23 nV rms at 9.4 SPS, gain = 128 (930 µA typical)
  • Low power: 24 nV rms at 1.17 SPS, gain = 128 (255 µA typical)
  • Mid power: 20 nV rms at 2.34 SPS, gain = 128 (355 µA typical)
  • Full power: 23 nV rms at 9.4 SPS, gain = 128 (930 µA typical)
  • Up to 22 noise free bits in all power modes (gain = 1)
  • Output data rate
    • Full power: 9.38 SPS to 19,200 SPS
    • Mid power: 2.34 SPS to 4800 SPS
    • Low power: 1.17 SPS to 2400 SPS
  • Full power: 9.38 SPS to 19,200 SPS
  • Mid power: 2.34 SPS to 4800 SPS
  • Low power: 1.17 SPS to 2400 SPS
  • Rail-to-rail analog inputs for gains > 1
  • Simultaneous 50 Hz/60 Hz rejection at 25 SPS (single cycle settling)
  • Diagnostic functions (which aid safe integrity level (SIL) certification)
  • Crosspoint multiplexed analog inputs
    • 8 differential/15 pseudo differential inputs
  • 8 differential/15 pseudo differential inputs
  • See data sheet for additional features
  • Analog to Digital Converters
    IBIS Models
    Reference Designs
    Software & Systems Requirements
    Data Sheets
    Documentnote
    AD7124-8: 8-Channel, Low Noise, Low Power, 24-Bit, Sigma-Delta ADC with PGA and Reference Data Sheet (Rev. D)PDF 1.73 M
    Application Notes
    Documentnote
    AN-1392: How to Calculate Offset Errors and Input Impedance in ADC Converters with Chopped Amplifiers (Rev. 0)PDF 99.17 K
    User Guides
    Documentnote
    UG-856: Evaluation Board for the AD7124-8 8-Channel, Low Noise, Low Power, 24-bit Σ-Δ ADC with In-Amp and ReferencePDF 4.94 M
    Order Information
    Part NumberPackagePacking QtyTemp RangePrice 100-499Price 1000+RoHS
    AD7124-8BCPZ Contact ADI32 ld LFCSP (5x5x.75mm) w/3.6exposed padOTH 490-40 to 125C5.284.93Y
    AD7124-8BCPZ-RL Contact ADI32 ld LFCSP (5x5x.75mm) w/3.6exposed padREEL 5000-40 to 125C5.284.93Y
    AD7124-8BCPZ-RL7 Contact ADI32 ld LFCSP (5x5x.75mm) w/3.6exposed padREEL 1500-40 to 125C04.93Y
    Evaluation Boards
    Part NumberDescriptionPriceRoHS
    EVAL-AD7124-8SDZEvaluation Board59Y
    EVAL-SDP-CB1ZEvaluation Controller board SDP99Y
    Reference Materials
    AD7124-8:集成PGA和基准电压源的8通道、 低噪声、低功耗24位Σ-Δ型ADC (Rev. D) ad7124-8
    AD7124-8: 8-Channel, Low Noise, Low Power, 24-Bit, Sigma-Delta ADC with PGA and Reference Data Sheet (Rev. D) ad7124-8
    AD7124-8 IBIS Model ad7124-8
    CN0381 / CN0383 /CN0384 Design & Integration Files adp1720
    CN0376 Design & Integration Files adp2441
    AD7124-4/AD7124-8 Eval+ Software ad7124-8
    AN-1392: 如何计算集成斩波放大器的ADC转换器的失调误差和输入阻抗 (Rev. 0) ad7770
    AN-1392: How to Calculate Offset Errors and Input Impedance in ADC Converters with Chopped Amplifiers (Rev. 0) ad7770
    UG-856: Evaluation Board for the AD7124-8 8-Channel, Low Noise, Low Power, 24-bit Σ-Δ ADC with In-Amp and Reference ad7124-8
    CN-0384:采用低功耗、精密、 24 位 Σ- 型 ADC 的全集成式热电偶测量系统 adp1720
    CN-0383:采用低功耗、精密、 24 位 Σ- 型 ADC 的全集成式 3 线 RTD 测量系统 adp1720
    CN-0381:采用低功耗、精密、 24 位 Σ- 型 ADC 的全集成式 4 线 RTD 测量系统 adp1720
    RTD温度测量系统对ADC的 要求 ad7124-8