Texas Instruments ADS8681IRUMR

Overview

ADS8681IRUMR from Texas Instruments is a 16-bit, 1-MSPS successive approximation register (SAR) analog-to-digital converter with integrated analog front-end, programmable bipolar/unipolar input ranges (±12.288 V to ±2.56 V or 0–12.288 V), on-chip 4.096-V reference (7 ppm/°C drift), and multiSPI™ interface. It operates from a single 5-V analog supply with 1.65–5-V I/O compatibility and delivers ±0.4 LSB DNL, 92 dB SNR, and –107 dB THD for high-precision industrial data acquisition.

For engineers reviewing the ADS8681IRUMR datasheet, ADS8681IRUMR pinout, ADS8681IRUMR application, or ADS8681IRUMR equivalent, this page provides verified specifications, WQFN-16 pin functions, real-world use cases in servo drive control and semiconductor test systems, and two validated alternative parts with documented technical and application differences.

Technical Context

The ADS8681IRUMR implements a true single-supply SAR ADC architecture with integrated PGA, 2nd-order LPF, overvoltage protection (±20 V), and software-configurable gain/offset calibration per input range. Its constant ≥1 MΩ resistive input impedance is maintained across all 9 selectable ranges without external components.

It supports three serial interface modes - standard SPI, multiSPI daisy-chain, and source-synchronous (internal or external clock) - with RVS signal indicating conversion status and ALARM output enabling high/low threshold monitoring independent of host polling.

Key Specifications

Pinout & Package

ADS8681IRUMR is housed in a 4.00 mm × 4.00 mm, 16-pin WQFN (RUM) package with wettable flanks, optimized for automated optical inspection and thermal performance (R_θJB = 7.4°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS8685IRUMR and AD7606C-16BSTZ, the ADS8681IRUMR uniquely balances single-channel speed (1 MSPS), software-defined range agility, and robust ±20-V OVP - making it optimal for adaptive industrial I/O where signal conditioning varies dynamically per channel.

Availability

ADS8681IRUMR is available at Aetrix Electronics and suitable for analog input modules, servo drive control modules, and semiconductor test systems requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for ADS8681IRUMR 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

Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of expertise in precision data converters and industrial-grade IC design.

The ADS868x family was engineered for rugged industrial data acquisition - integrating protection, programmability, and high accuracy into a single-chip solution to replace multi-component front-ends in PLCs, test equipment, and motion controllers.

FAQ

What input voltage ranges does the ADS8681IRUMR support?

The ADS8681IRUMR supports nine software-programmable input ranges: five bipolar (±12.288 V, ±10.24 V, ±6.144 V, ±5.12 V, ±2.56 V) and four unipolar (0–12.288 V, 0–10.24 V, 0–6.144 V, 0–5.12 V). Range selection is performed by writing to internal configuration registers via the multiSPI interface, and gain/offset errors are factory-trimmed for each range to ensure dc precision without external calibration.

Does the ADS8681IRUMR require an external reference voltage?

No, the ADS8681IRUMR includes a highly stable on-chip 4.096-V reference with 7 ppm/°C maximum drift (WQFN package), eliminating the need for an external reference in most applications. The REFIO pin can be configured as an output to drive the internal ADC or as an input to accept an external reference (4.046–4.146 V), providing flexibility for systems requiring tighter reference accuracy or synchronization across multiple ADCs.

How does the ALARM function operate on the ADS8681IRUMR?

The ALARM pin on the ADS8681IRUMR is a hardware comparator output that asserts high when the converted input voltage exceeds user-defined high or low thresholds stored in internal registers. It operates independently of host SPI communication, enabling immediate fault response - for example, triggering an emergency stop in a servo drive before the next CPU interrupt cycle. Thresholds are programmable in LSB steps matching the selected input range.

What is the purpose of the RVS pin on the ADS8681IRUMR?

The RVS (Ready Valid Signal) pin on the ADS8681IRUMR indicates ADC conversion status: it goes high at the end of conversion and remains high until the next CONVST edge or CS assertion. In source-synchronous modes, RVS also serves as the data-valid strobe synchronized to SCLK. This eliminates the need for fixed delay timing or status register polling, enabling deterministic, low-latency data capture in real-time control loops using the ADS8681IRUMR.

Can the ADS8681IRUMR interface with a 1.8-V microcontroller?

Yes, the ADS8681IRUMR supports I/O voltages from 1.65 V to 5 V on its DVDD supply, making it fully compatible with 1.8-V microcontrollers. Digital pins (SCLK, SDI, SDO-0, SDO-1, CONVST/CS, RST, ALARM/RVS) meet CMOS logic thresholds at DVDD = 1.8 V (VIH = 1.44 V min, VOL = 0.36 V max), and the device maintains full 1-MSPS performance and specification compliance across the entire DVDD range.