Analog Devices Inc. AD7902BRQZ-RL7

Overview

AD7902BRQZ-RL7 from Analog Devices is a dual 16-bit pseudo-differential successive approximation register (SAR) ADC with simultaneous sampling, 1 MSPS throughput, ±2.5 LSB max INL, 91 dB SINAD at 1 kHz, and 12.0 mW total power at full rate - used in high-precision redundant data acquisition and medical instrumentation requiring matched channel performance.

For engineers reviewing the AD7902BRQZ-RL7 datasheet, AD7902BRQZ-RL7 pinout, AD7902BRQZ-RL7 application, or AD7902BRQZ-RL7 equivalent, key selection criteria include simultaneous dual-channel conversion timing, channel-to-channel isolation (−112 dB), reference voltage flexibility (2.4 V to 5.1 V), and QSOP-20 package compatibility with space-constrained industrial sensor interfaces.

Technical Context

The AD7902BRQZ-RL7 implements two independent SAR ADC cores sharing no analog front-end resources, enabling true simultaneous sampling with aperture delay match ≤2.0 ns. Each channel features its own dedicated reference input (REF1/REF2), power supply (VDD1/VDD2), and digital interface (CNV1/CNV2, SCK1/SCK2, SDO1/SDO2).

Its serial interface supports both CS mode (active-low chip select) and chain mode (daisy-chainable 3-wire SPI), with logic-level independence via separate VIO1/VIO2 supplies (1.8 V to 5.5 V). No pipeline delay ensures deterministic latency: conversion result is available within 710 ns after CNVx rising edge.

Key Specifications

Pinout & Package

AD7902BRQZ-RL7 is housed in a 20-lead QSOP package (5.3 mm × 10.2 mm, 0.65 mm pitch), RoHS-compliant and rated for extended industrial temperature operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-channel SAR ADC applications.

Compared with AD7903BRQZ-RL7, the AD7902BRQZ-RL7 supports simpler single-ended sensor interfacing with ground-referenced negatives; compared with ADS8860IDRCT, it delivers hardware-enforced simultaneity and channel isolation essential for safety-critical redundancy and motor control.

Availability

AD7902BRQZ-RL7 is available at Aetrix Electronics and suitable for battery-powered equipment, medical instrumentation, and automated test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD7902BRQZ-RL7 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 Wilmington, MA.

The AD7902BRQZ-RL7 belongs to the PulSAR® family of precision SAR ADCs, engineered for applications demanding simultaneous sampling, low power, and guaranteed monotonicity in harsh industrial and medical environments.

FAQ

What is the maximum recommended reference voltage for AD7902BRQZ-RL7?

The AD7902BRQZ-RL7 supports an external reference voltage range of 2.4 V to 5.1 V per channel (REF1/REF2). Operation above 5.1 V violates absolute maximum ratings and may cause permanent damage. At 5.0 V reference, the device achieves optimal AC performance: 91 dB SINAD and −105 dB THD at 1 kHz. Using 5.1 V is permissible but offers no performance benefit and reduces margin against overvoltage transients.

Does AD7902BRQZ-RL7 support true differential input mode?

No, the AD7902BRQZ-RL7 implements pseudo-differential input architecture: INx+ accepts 0 V to VREF, while INx− serves as a ground-sense reference point (not a true complementary input). For true differential operation (±VREF/2), the pin-compatible AD7903BRQZ-RL7 must be used. Attempting differential signaling on AD7902BRQZ-RL7 will violate input voltage limits and degrade INL performance.

How does the AD7902BRQZ-RL7 achieve simultaneous sampling with no pipeline delay?

The AD7902BRQZ-RL7 uses two independent successive approximation register (SAR) cores, each with its own track-and-hold circuit and charge redistribution DAC. On the CNVx rising edge, both channels sample simultaneously; conversion proceeds in parallel with no shared pipeline stages. Results appear on SDO1/SDO2 within 710 ns, with zero-cycle latency - unlike sigma-delta or pipelined ADCs that introduce fixed delays.

Can AD7902BRQZ-RL7 operate from a single 3.3 V supply?

No. The AD7902BRQZ-RL7 requires three distinct supply domains: VDDx (2.375 V–2.625 V analog core), VIOx (1.8 V–5.5 V digital interface), and REFx (2.4 V–5.1 V reference). A single 3.3 V rail cannot meet VDDx specification and would exceed maximum VDD rating (2.625 V), risking latch-up or parametric failure. Separate LDOs for VDD1/VDD2 and REF1/REF2 are mandatory.

What is the significance of channel-to-channel isolation of −112 dB in AD7902BRQZ-RL7?

The −112 dB channel-to-channel isolation at 10 kHz means that a full-scale signal on Channel 1 couples into Channel 2 at a level 112 dB below full scale - equivalent to ~0.25 µV for a 5 V range. This prevents crosstalk-induced measurement errors in applications like dual-axis inertial sensing or simultaneous voltage/current monitoring, where correlated noise would corrupt computed power or torque values.