Analog Devices Inc. AD7989-5BRMZ

Overview

AD7989-5BRMZ from Analog Devices is an 18-bit, 500 kSPS successive approximation register (SAR) analog-to-digital converter with true differential input, ±V_REF range, zero-latency architecture, and SPI-compatible serial interface. It operates from a single 2.5 V supply with independent 1.8 V–5 V logic interface (VIO), supports external reference voltages from 2.4 V to 5.1 V, and delivers 97 dB SINAD at 1 kHz with 5 V reference-enabling high-fidelity data acquisition in precision medical instrumentation.

For engineers reviewing the AD7989-5BRMZ datasheet, AD7989-5BRMZ pinout, AD7989-5BRMZ application, or AD7989-5BRMZ equivalent, this page provides verified technical context, validated pin functions, confirmed power/performance trade-offs at 500 kSPS, and two rigorously cross-referenced alternative SAR ADCs for precision measurement systems requiring 18-bit resolution and low-noise dynamic performance.

Technical Context

The AD7989-5BRMZ implements a charge-redistribution SAR architecture with integrated track-and-hold, eliminating pipeline delay and enabling immediate conversion result availability after CNV rising edge. Its differential input stage accepts ±V_REF signals with 67 dB CMRR at 450 kHz and supports common-mode ranges centered at 0.5×V_REF ±0.025×V_REF.

It features a proprietary SPI-/QSPI-/MICROWIRE-/DSP-compatible serial interface with dual operating modes: CS mode (SDO enabled when CNV or SDI/CS is low) and chain mode (daisy-chaining multiple ADCs via SDI/CS). Power scales linearly with throughput-2 mW on VDD alone at 500 kSPS-and includes separate VIO supply for logic-level flexibility across 1.8 V, 2.5 V, 3 V, and 5 V host systems.

Key Specifications

Pinout & Package

AD7989-5BRMZ is packaged in a 10-lead MSOP (RM-10) with exposed pad, measuring 3 mm × 3 mm × 1.1 mm. Thermal resistance θ_JA = 200°C/W (natural convection), θ_JC = 44°C/W. The exposed pad is not electrically required but recommended for thermal relief.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 18-bit SAR ADC applications.

Compared with AD7989-5BRMZ, AD7691BCPZ-RL7 offers lower cost and simpler supply scheme but sacrifices throughput, interface flexibility, and daisy-chain capability; AD4011BCPZ-RL7 improves SNR by 3 dB but increases power and footprint-making AD7989-5BRMZ the optimal balance of speed, efficiency, and integration for compact, multi-channel precision DAQ.

Availability

AD7989-5BRMZ is available at Aetrix Electronics and suitable for automated test equipment, medical instrumentation, and machine automation requiring stable component supply, long-term lifecycle support, and traceable sourcing for Class I/II medical and industrial OEM programs.

Supply support for AD7989-5BRMZ 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 centers worldwide and ISO 9001-certified manufacturing.

The AD7989-5BRMZ belongs to Analog Devices' precision SAR ADC product line, engineered for high-resolution, low-power, zero-latency data acquisition in medical, industrial, and test equipment where accuracy, timing determinism, and thermal efficiency are critical.

FAQ

What is the maximum sample rate supported by the AD7989-5BRMZ?

The AD7989-5BRMZ supports a maximum throughput of 500 kSPS, as confirmed in the Rev. C datasheet Table 2 and Timing Specifications section. This is fixed for the -5 variant (AD7989-5), distinguishing it from the 100 kSPS AD7989-1. At this rate, conversion time is 1600 ns and cycle time is 2 μs, with acquisition time of 400 ns-enabling accurate sampling of signals up to 10 MHz bandwidth.

Does the AD7989-5BRMZ require an external clock for conversion?

No, the AD7989-5BRMZ does not require an external clock for the conversion process. As stated in the Theory of Operation section, it contains an on-board conversion clock. The SCK signal is used solely for serial data readout timing-not for controlling the SAR conversion cycle-allowing asynchronous sampling triggered by the CNV pin independent of SCK activity.

Can the AD7989-5BRMZ operate with a 1.8 V digital interface supply?

Yes, the AD7989-5BRMZ supports VIO from 1.71 V to 5.5 V, explicitly including 1.8 V logic levels. Per Table 3 and Digital Inputs specifications, VIH and VIL thresholds scale with VIO-e.g., at VIO = 1.8 V, VIH ≥ 1.62 V and VIL ≤ 0.18 V-ensuring reliable interfacing with low-voltage FPGAs and microcontrollers without level translation.

What is the purpose of the exposed pad on the AD7989-5BRMZ MSOP package?

The exposed pad on the AD7989-5BRMZ (RM-10 package) is thermally conductive but not electrically required. As noted in Figure 3 notes and Table 6, it may be connected to GND for improved thermal dissipation-reducing θ_JA in practical layouts-but electrical performance remains fully specified without this connection. No internal circuitry is tied to the pad.

How does the AD7989-5BRMZ handle reference voltage sourcing?

The AD7989-5BRMZ requires an external reference voltage applied to the REF pin, with a valid range of 2.4 V to 5.1 V. The device draws up to 250 µA from REF (Table 3), so the reference source must be low-noise and capable of supplying this current with <10 µF local decoupling to GND. Internal reference is not provided-designs must use precision external references like ADR4550 or REF102.