Features and Benefits
- 8-channel, 24-bit simultaneous sampling analog-to-digital converter (ADC)
- Single-ended or true differential inputs
- Programmable gain amplifier (PGA) per channel (gains of 1, 2, 4, and 8)
- Low dc input current
- ±1.5 nA (differential)
- ±4 nA (single-ended)
- Up to 16 kSPS output data rate (ODR) per channel
- Programmable ODRs and bandwidth
- Sample rate converter (SRC) for coherent sampling
- Sampling rate resolution up to 15.2 µSPS
- Low latency sinc3 filter path
- Adjustable phase synchronization
- Internal 2.5 V reference
- Two power modes optimizing power dissipation and performance: high resolution mode and low power mode
- Low resolution successive approximation (SAR) ADC for system and chip diagnostics
- Power supply
- Bipolar (±1.65 V) or unipolar (3.3 V) supplies
- Digital input/output (I/O) supply: 1.8 V to 3.6 V
- Performance temperature range: –40°C to +105°C
- Functional temperature range: –40°C to +125°C
- Combined ac and dc performance
- 108 dB signal-to-noise ratio (SNR)/dynamic range at 16 kSPS in high resolution mode
- −109 dB total harmonic distortion (THD)
- ±7 ppm integral nonlinearity (INL)
- ±40/PGAGAIN offset error and ±0.1% gain error
- ±10 ppm/°C typical temperature coefficient
The AD7779 is an 8-channel, simultaneous sampling ADC. There are eight full Σ-Δ ADCs on chip. The AD7779 provides an ultralow input current to allow direct sensor connection. Each input channel has a programmable gain stage allowing gains of 1, 2, 4, and 8 to map lower amplitude sensor outputs into the full-scale ADC input range, maximizing the dynamic range of the signal chain. The AD7779 accepts VREF from 1 V up to 3.6 V. The analog inputs accept unipolar (0 V to VREF/GAIN) or true bipolar (±VREF/GAIN/2 V) analog input signals with 3.3 V or ±1.65 V analog supply voltages. The analog inputs can be configured to accept true differential, pseudo differential, or singleended signals to match different sensor output configurations.
Each channel contains an ADC modulator and a sinc3, low latency digital filter. An SRC is provided to allow fine resolution control over the AD7779 ODR. This control can be used in applications where the ODR resolution is required to maintain coherency with 0.01 Hz changes in the line frequency. The SRC is programmable through the serial port interface (SPI). The AD7779 implements two different interfaces: a data output interface and SPI control interface. The ADC data output interface is dedicated to transmitting the ADC conversion results from the AD7779 to the processor. The SPI interface is used to write to and read from the AD7779 configuration registers and for the control and reading of data from the SAR ADC. The SPI interface can also be configured to output the Σ-Δ conversion data.
The AD7779 includes a 12-bit SAR ADC. This ADC can be used for AD7779 diagnostics without having to decommission one of the Σ-Δ ADC channels dedicated to system measurement functions. With the use of an external multiplexer, which can be controlled through the three general-purpose inputs/outputs pins (GPIOs), and signal conditioning, the SAR ADC can be used to validate the Σ-Δ ADC measurements in applications where functional safety is required. In addition, the AD7779 SAR ADC includes an internal multiplexer to sense internal nodes.
The AD7779 contains a 2.5 V reference and reference buffer. The reference has a typical temperature coefficient of 10 ppm/°C. The AD7779 offers two modes of operation: high resolution mode and low power mode. High resolution mode provides a higher dynamic range while consuming 10.75 mW per channel; low power mode consumes just 3.37 mW per channel at a reduced dynamic range specification.
The specified operating temperature range is −40°C to +105°C, although the device is operational up to +125°C.
- Circuit breakers
- General-purpose data acquisition
- Electroencephalography (EEG)
- Industrial process control
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Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (1)
The EVAL-AD7770FMCZ/EVAL-AD7771FMCZ/EVAL-AD7779FMCZ evaluation kit features the AD7770, AD7771, and AD7779 24-bit, analog-to-digital converters (ADCs). The board interfaces with the system demonstration platform SDP-H1 controller board (EVAL-SDP-CH1Z). The SDP-H1 controller board supplies power to the EVAL-AD7770FMCZ/EVAL-AD7771FMCZ/EVAL-AD7779FMCZ evaluation board and also connects to a PC running a Windows® operating system via a USB cable. The AD777x evaluation software fully configures the AD7770, AD7771, and AD7779 device register functionality and provides dc and ac time domain analysis in the form of waveform graphs, histograms, and associated noise analysis for ADC performance evaluation.
The EVAL-AD7770FMCZ/EVAL-AD7771FMCZ/EVAL-AD7779FMCZ evaluation board allows the user to evaluate the features of the ADC. The user PC software executable controls the AD7770, AD7771, and AD7779 over the USB cable through the SDP-H1 controller board.
Full specifications for the AD7770, AD7771, or AD7779 are available in the AD7770, AD7771, or AD7779 data sheets and should be consulted in conjunction with user guide UG-884 when working with the evaluation board.
Documentation & Resources
AN-1405: Diagnostic Features on the AD7770 and AD7779 (Rev. A)4/3/2017
AN-1393: Translating System Level Protection and Measurement Requirements to ADC Specifications (Rev. 0)2/26/2016
AN-1392: How to Calculate Offset Errors and Input Impedance in ADC Converters with Chopped Amplifiers (Rev. 0)2/26/2016
AN-1388: Coherent Sampling for Power Quality Measurements Using the AD7779 24-Bit Simultaneous Sampling Sigma-Delta ADC (Rev. 0)2/26/2016
AD777X: FAQs (EngineerZone)10/21/2021
DC Energy Metering Applications2/5/2021 Analog Dialogue
Newest Sigma-Delta ADC Architecture Averts Disrupted Data Flow When Synchronizing Critical Distributed Systems9/1/2019 Analog Dialogue
Integrated Capacitive PGAs in ADCs: Redefining Performance8/1/2016 Analog Dialogue
Measuring VSWR and Gain in Wireless Systems11/1/2005
Software & Systems Requirements
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.