Analog Devices Inc. AD7984BRMZ

Overview

AD7984BRMZ from Analog Devices is an 18-bit, 1.33 MSPS successive approximation register (SAR) analog-to-digital converter with true differential input, ±VREF range, zero-latency architecture, and SPI/QSPI/MICROWIRE-compatible serial interface. It operates from a single 2.5 V supply with separate 1.8 V–5 V digital I/O (VIO), delivering 99.7 dB dynamic range and −110.5 dB THD at 1 kHz for high-fidelity data acquisition in precision instrumentation.

For engineers reviewing the AD7984BRMZ datasheet, AD7984BRMZ pinout, AD7984BRMZ application, or AD7984BRMZ equivalent, key selection considerations include its 10-lead MSOP/LFCSP package, daisy-chain capability, external reference flexibility (2.9 V–5.1 V), guaranteed no missing codes, and low 10.5 mW total power at full throughput-critical for automated test equipment and medical signal chain design.

Technical Context

The AD7984BRMZ implements a charge redistribution SAR architecture with on-chip track-and-hold, eliminating pipeline delay and enabling true zero-latency conversion. Its differential input stage accepts ±VREF signals with 67 dB CMRR at 450 kHz and supports common-mode ranges centered at VREF/2 (±2.5% tolerance).

Digital interfacing uses a proprietary SPI-compatible 3-/4-wire protocol with optional busy indicator and SDI-driven daisy-chain mode-allowing multiple AD7984BRMZ units to share one SDO line with 18-cycle inter-device latency. The CNV rising edge initiates sampling and selects interface mode based on SDI logic level.

Key Specifications

Pinout & Package

AD7984BRMZ is available in two 10-lead packages: MSOP (RM-10, θJA = 200°C/W) and LFCSP (CP-10-9, θJA = 48.7°C/W). Both feature identical pin functions and pin-to-pin compatibility. The exposed paddle in LFCSP must be connected to GND for thermal and electrical performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7984BRMZ, AD7982BRMZ offers identical form-factor and timing but trades 1.2 dB dynamic range for lower cost, while AD4003BCPZ-RL7 delivers higher performance and integration at the expense of pin compatibility and increased package size-making AD7984BRMZ optimal for drop-in upgrades of legacy AD7982 designs requiring verified 99.7 dB performance.

Availability

AD7984BRMZ is available at Aetrix Electronics and suitable for automated test equipment, medical instruments, and machine automation requiring stable component supply, long-term lifecycle support, and traceable sourcing from authorized channels.

Supply support for AD7984BRMZ 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 R&D and manufacturing facilities worldwide.

The AD7984BRMZ belongs to Analog Devices' precision SAR ADC product line, engineered for applications demanding high resolution, low latency, and robust serial interfacing in industrial, medical, and test instrumentation signal chains.

FAQ

What is the maximum recommended reference voltage for AD7984BRMZ?

The AD7984BRMZ supports an external reference voltage range of 2.9 V to 5.1 V. At 5.0 V, it achieves optimal dynamic range (99.7 dB) and SNR (98.5 dB). Exceeding 5.1 V violates absolute maximum ratings and risks permanent damage to the REF pin. For best performance with lower noise floors, use a low-drift, low-noise reference IC such as the ADR4550, and always decouple REF to GND with a 10 µF X5R ceramic capacitor placed within 2 mm of the AD7984BRMZ package.

Does AD7984BRMZ require an external driver amplifier?

The AD7984BRMZ does not strictly require an external driver amplifier for DC or low-frequency signals, but Analog Devices explicitly recommends the ADA4941 for high-fidelity AC applications. This is because the AD7984BRMZ's input impedance varies dynamically during acquisition, and the ADA4941 provides low output impedance, high slew rate (25 V/µs), and excellent settling behavior to maintain 18-bit accuracy at full 1.33 MSPS throughput. Without a suitable driver, THD and SNR degrade significantly above 10 kHz.

Can AD7984BRMZ operate with VIO = 1.8 V while maintaining 1.33 MSPS throughput?

No. When VIO ≤ 2.3 V, the AD7984BRMZ maximum throughput is reduced to 833 kSPS per datasheet Table 5. To sustain 1.33 MSPS, VIO must exceed 2.3 V-minimum specified values are 2.3 V for timing parameters and 2.37 V for VDD. At VIO = 1.8 V, the SCK period increases to ≥22 ns, limiting conversion rate and increasing tDSDO to 14–21 ns, which constrains host controller timing margins. Use VIO ≥ 2.5 V for full-rate operation.

Is AD7984BRMZ pin-compatible with other devices in the same family?

Yes. AD7984BRMZ is pin-for-pin compatible with the AD7982BRMZ, sharing identical 10-lead MSOP/LFCSP footprints, pin functions, and interface protocols. This allows direct replacement in existing designs to upgrade from 98.5 dB to 99.7 dB dynamic range without PCB revision. However, it is not compatible with AD4003 (16-lead LFCSP) or AD7691 (20-lead TSSOP), which differ in pin count, layout, and reference architecture.

How does the daisy-chain mode function on AD7984BRMZ?

In daisy-chain mode (enabled by holding SDI low at CNV rising edge), the AD7984BRMZ accepts upstream data on SDI and outputs its own 18-bit conversion result plus that upstream data on SDO after an 18-SCK-cycle delay. This allows N AD7984BRMZ devices to share one SDO line and one SCK line, reducing host interface complexity. Each device's CNV must be tied together for synchronous sampling, and the host reads 18×N bits per cycle-requiring precise SCK edge alignment and sufficient setup/hold timing per Table 4.