Texas Instruments ADS8681IPWR

Overview

ADS8681IPWR 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, 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 ±20 V input overvoltage protection - deployed in industrial analog input modules requiring high dc precision and robust signal conditioning.

For engineers reviewing the ADS8681IPWR datasheet, ADS8681IPWR pinout, ADS8681IPWR application, or ADS8681IPWR equivalent, key selection considerations include its software-programmable input range flexibility, constant ≥1 MΩ resistive input impedance across all ranges, extended –40°C to +125°C operation, daisy-chain-capable multiSPI interface, and integrated overvoltage protection up to ±20 V without external clamping.

Technical Context

The ADS8681IPWR implements a true SAR architecture with internal PGA, second-order LPF, and programmable gain/offset calibration per input range. Its analog front-end maintains ≥1 MΩ input impedance regardless of selected range, enabling direct connection to high-impedance sensors without external buffering.

It supports three serial interface modes: standard SPI (CPOL/CPHA configurable), multiSPI with dual SDO outputs for daisy-chaining, and source-synchronous modes using either internal or external clock - all operating up to 66.67 MHz with sub-10 ns timing margins.

Key Specifications

Pinout & Package

TSSOP-16 (PW) package: 5.00 mm × 4.40 mm body, 0.65 mm pitch, surface-mount, lead-free, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS8685IPWR, the ADS8681IPWR delivers twice the sampling rate and optimized THD for dynamic signal fidelity, while AD7606C-16BSTZ trades per-channel configurability for multi-channel simultaneity - making ADS8681IPWR the preferred choice for compact, software-adaptable single-channel industrial DAQ nodes.

Availability

ADS8681IPWR is available at Aetrix Electronics and suitable for analog input modules, semiconductor test equipment, and servo drive control modules requiring stable component supply, long-term industrial lifecycle support, and guaranteed traceable sourcing.

Supply support for ADS8681IPWR 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, embedded processing, and connectivity technologies for industrial, automotive, and communications markets.

The ADS868x family was designed for high-precision, single-supply industrial data acquisition - integrating front-end protection, reference, and flexible range programming to replace multi-component signal chains in harsh environments.

FAQ

What input voltage ranges does the ADS8681IPWR support?

The ADS8681IPWR 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 - no external hardware changes are needed. Each range is factory-calibrated for gain and offset accuracy, ensuring consistent dc precision across all settings. The ADS8681IPWR maintains ≥1 MΩ input impedance regardless of selected range.

How does the multiSPI™ interface of the ADS8681IPWR differ from standard SPI?

The multiSPI™ interface of the ADS8681IPWR extends standard SPI with dual SDO outputs (SDO-0 and SDO-1/ALARM), enabling daisy-chain configurations for multi-device systems without additional chip-select lines. It supports three modes: standard SPI (CPOL/CPHA configurable), multiSPI with dual SDOs, and source-synchronous modes using internal or external clocks - all operating up to 66.67 MHz. Unlike basic SPI, multiSPI allows simultaneous readout of multiple ADS8681IPWR devices using a single SCLK and CS line, reducing host GPIO count and simplifying firmware for scalable acquisition systems.

Does the ADS8681IPWR require an external reference voltage?

No, the ADS8681IPWR does not require an external reference voltage - it integrates a precision 4.096-V reference with 7 ppm/°C maximum drift (TSSOP) and includes dedicated REFIO and REFCAP pins for decoupling. The REFIO pin can be configured as either a reference output or an external reference input (accepting 4.046–4.146 V), providing flexibility for systems needing tighter reference stability. When using the internal reference, a 4.7 µF capacitor is required on REFIO and a 10 µF capacitor on REFCAP. The ADS8681IPWR achieves 92 dB SNR and ±0.5 LSB INL using this on-chip reference.

What is the purpose of the ALARM/SDO-1/GPO pin on the ADS8681IPWR?

The ALARM/SDO-1/GPO pin on the ADS8681IPWR is a multifunction terminal configurable as a high/low threshold alarm output, secondary SPI data output (SDO-1), or general-purpose digital output. In alarm mode, it asserts high when the converted input exceeds user-defined upper or lower limits stored in internal registers - useful for overvoltage/undervoltage detection in motor drives or power supplies. In multiSPI daisy-chain mode, it serves as the second data output, allowing two bytes per conversion cycle. As GPO, it can be controlled via register write for system-level signaling - all functions are software-selectable without hardware modification.

What package options are available for the ADS8681IPWR?

ADS8681IPWR is offered exclusively in the TSSOP-16 (PW) package: 5.00 mm × 4.40 mm body size, 0.65 mm lead pitch, surface-mount, lead-free, and RoHS-compliant. This package is distinct from the WQFN-16 (RUM) variant used by other ADS868x family members (e.g., ADS8681IRUMR), which measures 4.00 mm × 4.00 mm. The TSSOP-16 provides robust thermal performance (RθJA = 95.7°C/W) and is optimized for automated assembly in industrial PCBs. Pinout is identical between PW and RUM packages, enabling layout reuse where mechanical constraints allow.