Analog Devices Inc. AD7694BRMZRL7

Overview

AD7694BRMZRL7 from Analog Devices is a 16-bit, pseudo-differential, successive-approximation 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 serves as a precision data acquisition front-end in portable instrumentation requiring low power and high DC/AC accuracy.

For engineers reviewing the AD7694BRMZRL7 datasheet, AD7694BRMZRL7 pinout, AD7694BRMZRL7 application, or AD7694BRMZRL7 equivalent, this page delivers verified specifications, real-world timing behavior, true differential input handling, SPI-compatible serial interface details, and validated alternative options for battery-powered and industrial measurement systems.

Technical Context

The AD7694BRMZRL7 uses a charge redistribution SAR architecture with on-chip track-and-hold, delivering zero pipeline delay and immediate data availability post-conversion. Its conversion clock is fully internal-SCK only controls serial readout, not sampling timing.

It supports pseudo-differential input (IN+ to IN−) with 0 V to VREF range referenced to external REF (1 V to VDD), and features dynamic reference input impedance requiring local 10 µF ceramic decoupling. Power scales linearly with throughput: 800 µA at 5 V/100 kSPS, 1 nA standby current.

Key Specifications

Pinout & Package

AD7694BRMZRL7 is housed in an 8-lead MSOP package (3.0 mm × 3.0 mm, 0.65 mm pitch), rated for −40°C to +85°C operation, with θ_JA = 200°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC1864LIMS8#PBF, AD7694BRMZRL7 delivers 2.5× higher throughput and tighter INL for modern portable instrumentation; versus AD7685BRMZ-REEL7, it trades true differential flexibility for simpler unipolar-compatible input architecture and lower system BOM count.

Availability

AD7694BRMZRL7 is available at Aetrix Electronics and suitable for battery-powered equipment, medical instruments, process control transmitters, and portable test equipment requiring stable component supply, long-lifecycle assurance, and RoHS-compliant packaging.

Supply support for AD7694BRMZRL7 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA, with design centers worldwide.

The AD7694BRMZRL7 belongs to Analog Devices' PulSAR® family of precision SAR ADCs, engineered for low-power, high-accuracy data acquisition in portable and industrial instrumentation where DC integrity and AC fidelity are equally critical.

FAQ

What is the maximum recommended reference voltage for AD7694BRMZRL7?

The AD7694BRMZRL7 supports an external reference voltage (REF) from 1 V up to VDD. When VDD = 5.25 V, REF may be set as high as 5.25 V. However, Analog Devices specifies optimal AC performance (e.g., 92 dB S/(N + D)) at VREF = 5 V with VDD = 5 V. Using REF > VDD is not permitted-the absolute maximum rating limits REF to VDD + 0.3 V, and operation above VDD degrades linearity and may violate reliability limits. Always decouple REF to GND with a 10 µF X5R ceramic capacitor placed adjacent to the pins.

Does AD7694BRMZRL7 require an external clock for conversion timing?

No, AD7694BRMZRL7 does not require an external clock for conversion timing. It contains a fully integrated conversion clock; the SCK signal is used solely for serial data readout after conversion completes. The CNV rising edge triggers sampling, and conversion finishes in 3.2 µs (at 5 V) regardless of SCK frequency. This architecture eliminates clock distribution complexity and jitter sensitivity-critical for maintaining 92 dB S/(N + D) performance. SCK only affects data transfer speed, not sampling accuracy or timing.

Can AD7694BRMZRL7 interface directly with a 3.3 V microcontroller SPI port?

Yes, AD7694BRMZRL7 supports direct SPI interfacing with 3.3 V microcontrollers. Its digital inputs (CNV, SCK) accept VIH ≥ 1.9 V at VDD = 3.3 V, and its SDO output drives VOH ≥ VDD − 0.3 V (≥3.0 V) and VOL ≤ 0.4 V-fully compatible with standard 3.3 V logic thresholds. No level shifters are needed. Ensure CNV and SCK rise/fall times remain <10 ns and that SDO load capacitance stays ≤50 pF, per Figure 2's timing load circuit, to maintain valid setup/hold margins.

What is the purpose of the IN− pin on AD7694BRMZRL7, and how should it be connected?

The IN− pin on AD7694BRMZRL7 serves as the pseudo-differential ground sense reference-not a true negative input. It establishes the common-mode baseline for the IN+ measurement, enabling rejection of noise shared between both nodes. IN− must be connected to the analog ground plane near the sensor or to a remote ground point (e.g., sensor shield return) to eliminate ground loop errors. It is not intended for active signal injection. Floating IN− or connecting it to VDD/GND other than the designated analog reference violates the specified 0 V to VREF input range and causes INL degradation or code errors.

How does power consumption scale with sample rate in AD7694BRMZRL7?

AD7694BRMZRL7 power consumption scales linearly with throughput due to automatic power-down between conversions. At 5 V, it draws 800 µA at 100 kSPS, ~200 µA at 25 kSPS, and just 4 µW (~0.8 µA) at 100 SPS. Standby current is 1 nA when CNV remains high. This behavior is confirmed in Figure 22 of the datasheet and enables aggressive duty-cycling strategies-e.g., waking every 100 ms to capture one sample, then returning to nanoamp sleep. Total energy per sample remains constant, making AD7694BRMZRL7 exceptionally efficient for intermittent monitoring.