AD7768 8-Channel, 24-Bit, Simultaneous Sampling ADC, Power Scaling, 110.8 kHz BW

The AD7768/AD7768-4 are 8-channel and 4-channel, simultaneous sampling sigma-delta (Σ-Δ) analog-to-digital converters (ADCs), respectively, with a Σ-Δ modulator and digital filter per channel, enabling synchronized sampling of ac and dc signals.

The AD7768/AD7768-4 achieve 108 dB dynamic range at a maximum input bandwidth of 110.8 kHz, combined with typical performance of ±2 ppm INL, ±50 µV offset error, and ±30 ppm gain error.

The AD7768/AD7768-4 user can trade off input bandwidth, output data rate, and power dissipation, and select one of three power modes to optimize for noise targets and power consumption. The flexibility of the AD7768/AD7768-4 allows them to become reusable platforms for low power dc and high performance ac measurement modules.

The AD7768/AD7768-4 have three modes: fast mode (256 kSPS maximum, 110.8 kHz input bandwidth, 51.5 mW per channel), median mode (128 kSPS maximum, 55.4 kHz input bandwidth, 27.5 mW per channel) and eco mode (32 kSPS maximum, 13.8 kHz input bandwidth, 9.375 mW per channel).

The AD7768/AD7768-4 offer extensive digital filtering capabilities, such as a wideband, low ±0.005 dB pass-band ripple, antialiasing low-pass filter with sharp roll-off, and 105 dB stop band attenuation at the Nyquist frequency.

Frequency domain measurements can use the wideband linear phase filter. This filter has a flat pass band (±0.005 dB ripple) from dc to 102.4 kHz at 256 kSPS, from dc to 51.2 kHz at 128 kSPS, or from dc to 12.8 kHz at 32 kSPS.

The AD7768/AD7768-4 also offer sinc response via a sinc5 filter, a low latency path for low bandwidth, and low noise measurements. The wideband and sinc5 filters can be selected and run on a per channel basis.

Within these filter options, the user can improve the dynamic range by selecting from decimation rates of ×32, ×64, ×128, ×256, ×512, and ×1024. The ability to vary the decimation filtering optimizes noise performance to the required input bandwidth.

Embedded analog functionality on each ADC channel makes design easier, such as a precharge buffer on each analog input that reduces analog input current and a reference precharge buffer per channel reduces input current and glitches on the reference input terminals.

The device operates with a 5 V AVDD1A and AVDD1B supply, a 2.25 V to 5.0 V AVDD2A and AVDD2B supply, and a 2.5 V to 3.3 V or 1.8 V IOVDD supply (see the 1.8 V IOVDD Operation section for specific requirements for operating at 1.8 V IOVDD). The device requires an external reference; the absolute input reference voltage range is 1 V to AVDD1 − AVSS.

For the purposes of clarity within this document, the AVDD1A and AVDD1B supplies are referred to as AVDD1 and the AVDD2A and AVDD2B supplies are referred to as AVDD2. For the negative supplies, AVSS refers to the AVSS1A, AVSS1B, AVSS2A, AVSS2B, and AVSS pins.

The specified operating temperature range is −40°C to +105°C. The device is housed in a 10 mm × 10 mm 64-lead LQFP package with a 12 mm × 12 mm printed circuit board (PCB) footprint. Throughout this data sheet, multifunction pins, such as XTAL2/MCLK, are referred to either by the entire pin name or by a single function of the pin, for example MCLK, when only that function is relevant.

Applications

Features and Benefits
  • Precision ac and dc performance
  • 8-/4-channel simultaneous sampling
  • 256 kSPS maximum ADC output data rate per channel
  • 108 dB dynamic range
  • 110.8 kHz maximum input bandwidth (−3 dB bandwidth)
  • −120 dB total harmonic distortion (THD) typical
  • ±2 ppm of full-scale range (FSR) integral nonlinearity (INL), ±50 µV offset error, ±30 ppm gain error
  • Optimized power dissipation vs. noise vs. input bandwidth
  • Selectable power, speed, and input bandwidth (BW) modes
    - Fast: highest speed; 110.8 kHz BW, 51.5 mW per channel
    - Median: half speed, 55.4 kHz BW, 27.5 mW per channel
    - Eco: lowest power, 13.8 kHz BW, 9.375 mW per channel
  • Input BW range: dc to 110.8 kHz
  • Programmable input bandwidth/sampling rates
  • See data sheet for additional features
  • Analog to Digital Converters
    IBIS Models
    Software & Systems Requirements
    Data Sheets
    Documentnote
    AD7768/AD7768-4: 8-/4-Channel, 24-Bit, Simultaneous Sampling ADCs with Power Scaling, 110.8 kHz BW Data Sheet (Rev. A)PDF 2.3 M
    User Guides
    Documentnote
    UG-917: Evaluation Board for the AD7768 24-Bit, 8-Channel, Simultaneous Sampling, 256 kSPS, Sigma-Delta ADC with Power Scaling (Rev. 0)PDF 1.06 M
    Order Information
    Part NumberPackagePacking QtyTemp RangePrice 100-499Price 1000+RoHS
    AD7768BSTZ Production64 ld LQFP (10x10mm)OTH 160-40 to 105C22.3618.95Y
    AD7768BSTZ-RL Production64 ld LQFP (10x10mm)REEL 1500-40 to 105C22.3618.95Y
    Evaluation Boards
    Part NumberDescriptionPriceRoHS
    EVAL-AD7768FMCZEvaluation Board138Y
    EVAL-SDP-CH1ZSystem Demonstration Platform199Y
    Reference Materials
    AD7768/AD7768-4:8/4通道24位同步采样ADC,具备功耗调节功能,110.8 kHz带宽 (Rev. A) ad7768
    AD7768/AD7768-4: 8-/4-Channel, 24-Bit, Simultaneous Sampling ADCs with Power Scaling, 110.8 kHz BW Data Sheet (Rev. A) ad7768
    AD7768 IBIS Model ad7768
    AD7768 Evaluation Software ad7768
    UG-917: Evaluation Board for the AD7768 24-Bit, 8-Channel, Simultaneous Sampling, 256 kSPS, Sigma-Delta ADC with Power Scaling ( ad7768
    How High Performance Modular Instruments Enable Greater Applications and... ad7768