Analog Devices Inc. AD7679ASTZ

Overview

AD7679ASTZ from Analog Devices is an 18-bit, 570 kSPS, fully differential SAR analog-to-digital converter operating on a single 5 V supply. It delivers ±2.5 LSB INL, 103 dB dynamic range, and supports parallel (18-/16-/8-bit) or SPI/QSPI/MICROWIRE-compatible serial interface - deployed in high-precision CT scanners and geophone sensor systems.

For engineers reviewing the AD7679ASTZ datasheet, AD7679ASTZ pinout, AD7679ASTZ application, or AD7679ASTZ equivalent, key selection considerations include true differential input range (±VREF), no pipeline delay, on-board reference buffer, low power at partial throughput (150 μW @ 1 kSPS), and dual-package availability (48-lead LQFP/LFCSP).

Technical Context

The AD7679ASTZ employs charge redistribution SAR architecture with internal conversion clock and error correction circuitry, eliminating latency and enabling immediate data availability post-conversion. Its differential input stage accepts ±VREF (up to 5 V), with analog input CMRR of 68 dB at 100 kHz and aperture jitter of only 5 ps rms.

Dual digital interface modes are hardware-configurable via MODE0/MODE1 pins: 18-bit parallel, 16-bit high/low word, 8-bit byte, or 3-wire serial. Reference buffering is selectable via PDBUF pin, and REFBUFIN accepts 2.5 V to generate a stable 4.096 V internal reference output.

Key Specifications

Pinout & Package

AD7679ASTZ is available in two RoHS-compliant packages: 48-lead LQFP (7 mm × 7 mm) and 48-lead LFCSP (7 mm × 7 mm, exposed pad). Both support operation from –40°C to +85°C and share identical pin mapping per Analog Devices Rev. B datasheet.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-resolution SAR ADC applications.

Compared with AD7678ASTZ, AD7679ASTZ adds 70 kSPS throughput while maintaining identical linearity and packaging; versus AD7665ASTZ, it trades 2 bits of resolution for true differential input, integrated reference buffer, and guaranteed no missing codes - directly enabling higher-fidelity medical and geophysical measurements.

Availability

AD7679ASTZ is available at Aetrix Electronics and suitable for CT scanners, geophone sensor arrays, and high-dynamic instrumentation requiring stable component supply across long-lifecycle medical and industrial programs.

Supply support for AD7679ASTZ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA.

The AD7679ASTZ belongs to the PulSAR® family of precision SAR ADCs, designed specifically for applications demanding high resolution, fast throughput, and exceptional DC/AC accuracy without pipeline latency.

FAQ

What is the maximum recommended external reference voltage for AD7679ASTZ?

The AD7679ASTZ supports an external reference voltage (REF) from 3 V to AVDD + 0.1 V (i.e., up to 5.35 V). When using the internal reference buffer, apply 2.5 V to REFBUFIN to generate a nominal 4.096 V on REF - this configuration is validated in the datasheet and ensures optimal INL performance for AD7679ASTZ.

Does AD7679ASTZ support true differential input operation?

Yes, AD7679ASTZ supports true differential input operation with a full-scale range of ±VREF. The IN+ and IN– pins accept complementary analog signals, delivering 68 dB CMRR at 100 kHz. This capability is intrinsic to AD7679ASTZ's architecture and does not require external amplifiers or resistor networks.

Can AD7679ASTZ operate with a 3 V digital interface while using a 5 V analog supply?

Yes, AD7679ASTZ supports mixed-voltage operation: AVDD and DVDD are 5 V, while OVDD can be set to 3 V to interface with 3 V logic. The datasheet specifies OVDD range as 2.7 V to DVDD + 0.37 V, and all digital outputs (SDOUT, SYNC, SCLK) are level-shifted to OVDD - confirmed for AD7679ASTZ in Table 2 and Figure 2.

Is AD7679ASTZ pin-compatible with AD7674ASTZ or AD7676ASTZ?

Yes, AD7679ASTZ is explicitly stated as pin-to-pin compatible with AD7674ASTZ and AD7676ASTZ per the datasheet's "Pin-to-pin compatible upgrade" feature bullet. All three share identical 48-lead LQFP/LFCSP pinouts, power domains, and interface signaling - enabling direct replacement without PCB changes for AD7679ASTZ.

What is the minimum acquisition time required before conversion starts on AD7679ASTZ?

The AD7679ASTZ requires a minimum acquisition time (t8) of 250 ns, as specified in Table 3 (Timing Specifications). This interval begins after CNVST goes LOW and ends before the internal sample/hold transitions to hold state - a fixed timing parameter verified across –40°C to +85°C for AD7679ASTZ.