Analog Devices Inc. AD7946BRMZRL7

Overview

AD7946BRMZRL7 from Analog Devices is a 14-bit, 500 kSPS successive approximation register (SAR) ADC with pseudo-differential analog input, no pipeline delay, and single-supply 5 V operation. It delivers ±1 LSB max INL, 85 dB SINAD at 20 kHz, and 3.3 µW power at 100 SPS - optimized for high-precision, low-power data acquisition in portable instrumentation.

For engineers reviewing the AD7946BRMZRL7 datasheet, AD7946BRMZRL7 pinout, AD7946BRMZRL7 application, or AD7946BRMZRL7 equivalent, this page provides verified technical context, real-world interface timing constraints, validated alternative options, and design-meaningful specifications - all confirmed against Analog Devices' Rev. B datasheet and official package documentation.

Technical Context

The AD7946BRMZRL7 implements a charge redistribution SAR architecture with an integrated track-and-hold, enabling true 14-bit accuracy without missing codes and zero latency conversion. Its internal conversion clock eliminates dependency on SCK for sampling, supporting deterministic timing via CNV edge-triggered acquisition.

It features a proprietary SPI-compatible serial interface with dual-mode operation: CS mode (3- or 4-wire) and Chain mode (daisy-chain capable), both supporting BUSY indicator and 1.8 V–5 V logic-level compatibility via dedicated VIO supply. The analog input accepts 0 V to REF differential range with REF up to VDD, and exhibits 9 MHz −3 dB bandwidth and 2.5 ns aperture delay.

Key Specifications

Pinout & Package

AD7946BRMZRL7 is available in a 10-lead MSOP package (3 mm × 3 mm footprint, 0.5 mm pitch) with exposed pad connected to GND. Pinout matches both MSOP and LFCSP variants per Analog Devices Rev. B datasheet Figure 4 and Table 6.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 14-bit SAR ADC applications.

Compared with AD7942BRMZ and AD7686BRMZ, the AD7946BRMZRL7 uniquely balances 500 kSPS speed, 14-bit precision, and ultra-low standby power - making it optimal for portable, battery-constrained systems needing both bandwidth and longevity.

Availability

AD7946BRMZRL7 is available at Aetrix Electronics and suitable for battery-powered equipment, medical instruments, process control transmitters, and portable data acquisition systems requiring stable component supply across long production lifecycles.

Supply support for AD7946BRMZRL7 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.

The AD7946BRMZRL7 belongs to Analog Devices' PulSAR® family of precision SAR ADCs, designed specifically for applications demanding high resolution, low power, and deterministic timing in space- and energy-constrained systems.

FAQ

What is the maximum recommended reference voltage for AD7946BRMZRL7?

The AD7946BRMZRL7 supports REF from 0.5 V to VDD, with VDD rated 4.5 V to 5.5 V. Therefore, the maximum REF is 5.5 V - but operation at VDD = 5.5 V requires verification of REF stability and decoupling. For best AC performance, Analog Devices specifies 85 dB SINAD at REF = 5 V; higher REF increases full-scale range but may reduce SNR if reference noise rises. Always use a low-noise, well-decoupled reference source - e.g., ADR4550 - and place a 10 µF ceramic capacitor directly at the REF pin.

Does AD7946BRMZRL7 require an external driver amplifier?

The AD7946BRMZRL7 can be driven directly by low-impedance sources (<50 Ω), but an external driver amplifier is recommended for high-frequency or high-impedance signals to maintain THD and SNR. As shown in Figure 28 of the datasheet, THD degrades significantly above 25 kHz with RS > 100 Ω. For 20 kHz full-scale inputs, ADA4841-1 or AD8676 provide optimal noise and settling performance. The internal track-and-hold eliminates need for external sample-hold, but driver selection must account for 9 MHz input bandwidth and 2.5 ns aperture delay.

How does the daisy-chain mode work on AD7946BRMZRL7?

In daisy-chain (Chain) mode, AD7946BRMZRL7 uses SDI as a data-in path: when SDI is low at CNV rising edge, the device enters Chain mode. Conversion results from multiple AD7946BRMZRL7 units are concatenated onto a single SDO line, with each device delaying its output by 14 SCK cycles. This enables synchronized multi-channel capture without additional chip-select lines. The BUSY indicator remains functional, and SCK timing must meet VIO-dependent min/max periods (e.g., 17 ns for VIO > 4.5 V). No hardware modification is needed beyond wiring SDI of upstream device to SDO of downstream unit.

What is the meaning of "no pipeline delay" for AD7946BRMZRL7?

"No pipeline delay" means the AD7946BRMZRL7 outputs the conversion result of the sample triggered by the most recent CNV rising edge - with no intermediate stored or queued conversions. Unlike pipelined or sigma-delta ADCs, there is zero latency between acquisition and data availability: the 14-bit result appears on SDO within tCONV (≤1.6 µs) after CNV rises. This enables real-time control applications such as motor commutation or closed-loop feedback where deterministic, sub-microsecond response is essential - and eliminates the need for latency compensation in firmware.

Can AD7946BRMZRL7 operate with VIO = 1.8 V while VDD = 5 V?

Yes - AD7946BRMZRL7 fully supports independent VIO and VDD supplies, with VIO specified from 1.8 V to VDD + 0.3 V. At VIO = 1.8 V and VDD = 5 V, digital inputs (SDI, CNV, SCK) accept 0.3 × 1.8 V = 0.54 V (VIL) and 0.7 × 1.8 V = 1.26 V (VIH), while SDO drives VOH ≥ 1.5 V and VOL ≤ 0.4 V. This allows direct interfacing with 1.8 V FPGAs or microcontrollers without level shifters. However, SCK timing slows slightly: min period increases to 20 ns (per Table 4), and tDSDO delay extends to 17 ns - both remain compatible with standard 1.8 V logic families.