Analog Devices Inc. AD7694ARMZ

Overview

AD7694ARMZ from Analog Devices is a 16-bit, pseudo-differential, successive-approximation analog-to-digital converter (ADC) with no missing codes (B grade), 250 kSPS throughput at 5 V, ±4 LSB INL, 92 dB S/(N + D) at 20 kHz, and single-supply operation from 2.7 V to 5.25 V. It integrates an on-chip track-and-hold, internal conversion clock, and SPI-compatible serial interface - ideal for precision data acquisition in portable instrumentation.

For engineers reviewing the AD7694ARMZ datasheet, AD7694ARMZ pinout, AD7694ARMZ application, or AD7694ARMZ equivalent, key selection considerations include its 8-lead MSOP package, 1 nA standby current, pseudo-differential input range (0 V to VREF), absence of pipeline delay, and compatibility with SPI/QSPI/MICROWIRE/DSP hosts - all critical for low-power, high-accuracy sensor interfacing and battery-operated systems.

Technical Context

The AD7694ARMZ employs a charge redistribution SAR architecture with a built-in track-and-hold circuit, enabling true single-cycle acquisition and zero-latency conversion results. Its proprietary serial interface operates with CNV-triggered conversion and SDO output synchronized to SCK falling edges, supporting 16-bit straight-binary data without pipeline delay.

It features dynamic reference input impedance requiring local 10 µF ceramic decoupling at REF, rail-to-rail analog input compliance (−0.1 V to VDD + 0.1 V), and power scaling linearly with throughput - consuming only 540 µA at 2.7 V/100 kSPS and dropping to 1 nA in standby.

Key Specifications

Pinout & Package

AD7694ARMZ is housed in an 8-lead MSOP package (3.0 mm × 3.0 mm, 0.65 mm pitch) with exposed pad option per JEDEC MO-187-AA, rated for θJA = 200°C/W and θJC = 44°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit SAR ADC applications.

Compared with LTC1864L and AD7685BRMZ, the AD7694ARMZ uniquely balances 250 kSPS speed, 1 nA standby, pseudo-differential simplicity, and 8-lead MSOP compactness - making it optimal for space-constrained, battery-sensitive designs where true differential inputs are unnecessary.

Availability

AD7694ARMZ is available at Aetrix Electronics and suitable for portable medical sensors, industrial process monitoring, battery-powered data loggers, and test & measurement equipment requiring stable component supply, long-term lifecycle support, and guaranteed authenticity.

Supply support for AD7694ARMZ 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, with design and manufacturing expertise spanning precision converters, amplifiers, and RF solutions.

The AD7694ARMZ belongs to Analog Devices' PulSAR® family of low-power, high-accuracy SAR ADCs, engineered specifically for battery-operated instrumentation, industrial data acquisition, and medical devices demanding resolution, speed, and energy efficiency in minimal footprint.

FAQ

What is the maximum sampling rate of the AD7694ARMZ and under what conditions?

The AD7694ARMZ achieves a maximum throughput of 250 kSPS when operated with a 4.75 V to 5.25 V supply voltage and at temperatures from −40°C to +85°C. At lower supplies (2.7 V to 4.75 V), the maximum rate reduces to 150 kSPS due to internal timing constraints. This specification is confirmed in Table 2 of the Rev. B datasheet and verified by timing parameters tCONV = 3.2 µs and tCYC = 4 µs at 5 V.

Does the AD7694ARMZ require an external reference voltage, and what are the acceptable ranges?

Yes, the AD7694ARMZ requires an external reference voltage applied to the REF pin, which must be between 1 V and VDD (2.7 V to 5.25 V). The reference can be derived from a precision source like the ADR435 or buffered via an op amp such as the AD8031. Performance metrics including S/(N + D) and INL are specified with VREF = VDD, and Figure 11 shows SNR degradation below 2.5 V reference.

How does the AD7694ARMZ handle power management, and what is its standby current?

The AD7694ARMZ powers down automatically between conversions, resulting in current draw that scales linearly with throughput. Its standby current is specified as 1 nA (max) at 5 V and 25°C, rising to 50 nA over full temperature range - enabling multi-year operation in wake-on-event sensor nodes. This value is measured during acquisition phase with all digital inputs forced to VDD or GND, per Table 3 footnote 2.

Is the AD7694ARMZ pin-compatible with other devices in the PulSAR family, such as the AD7685?

No, the AD7694ARMZ is not pin-compatible with the AD7685. While both are 16-bit, 250 kSPS SAR ADCs, the AD7685 uses a 10-lead MSOP package with true differential inputs (IN+, IN−, VINA, VINB), whereas the AD7694ARMZ uses an 8-lead MSOP with pseudo-differential inputs (IN+, IN−, REF, GND, VDD, CNV, SCK, SDO). Pin count, function mapping, and package dimensions differ.

What digital interface protocols does the AD7694ARMZ support, and how is data transferred?

The AD7694ARMZ supports SPI®, QSPI™, MICROWIRE™, and DSP-compatible serial interfaces using a 3-wire configuration (CNV, SCK, SDO). Conversion is triggered by a rising edge on CNV; upon completion, the 16-bit straight-binary result is shifted out MSB-first on SDO, synchronized to SCK falling edges. No chip select (CS) is required, and data is valid immediately after tDSDO (20 ns @ 5 V), per Figure 24 timing diagram.