Texas Instruments ADS8691IPWR

Overview

ADS8691IPWR from Texas Instruments is an 18-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 low-drift reference, and multiSPI™ interface. It operates from a single 5-V analog supply with 1.65–5-V I/O support and delivers ±0.6 LSB DNL, 92.5 dB SNR, and ±1.75 LSB INL - suited for high-precision industrial data acquisition systems requiring robust overvoltage protection and software-configurable range selection.

For engineers reviewing the ADS8691IPWR datasheet, ADS8691IPWR pinout, ADS8691IPWR application, or ADS8691IPWR equivalent, this page provides verified technical context, validated pin functions, confirmed performance metrics across all supported input ranges, and real-world implementation guidance for analog input modules, semiconductor test equipment, and LCD panel characterization systems.

Technical Context

The ADS8691IPWR implements a true single-supply SAR architecture with integrated PGA, second-order LPF, and overvoltage protection circuitry rated for ±20 V (AVDD = 5 V) on AIN_P/AIN_GND. Its input impedance remains ≥1 MΩ across all 9 software-selectable ranges, and gain/offset errors are factory-trimmed per range to ensure dc precision without external calibration.

It supports three serial interface modes: standard SPI (CPOL/CPHA configurable), multiSPI daisy-chain (dual SDO outputs), and source-synchronous modes (internal or external clock). The RVS pin provides real-time ADC status indication, while ALARM/SDO-1/GPO enables high/low threshold monitoring independent of conversion cycles.

Key Specifications

Pinout & Package

TSSOP-16 package (5.00 mm × 4.40 mm), thermally enhanced for industrial operation from –40°C to +125°C. Pinout validated per TI SBAS777B Rev. B (March 2021), Figure 5-1 and Table 5-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS8860IPW and AD7606C-18BSTZ, the ADS8691IPWR uniquely integrates reference, OVP, and programmable range selection in a single TSSOP-16 package - reducing bill-of-materials, layout effort, and calibration overhead for modular, field-deployable DAQ systems.

Availability

ADS8691IPWR is available at Aetrix Electronics and suitable for analog input modules, semiconductor test equipment, and LCD panel characterization systems requiring stable component supply, long-term industrial lifecycle support, and guaranteed traceable sourcing.

Supply support for ADS8691IPWR 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 digital signal technologies, with decades of expertise in precision data converters and industrial-grade ICs.

The ADS869x family was designed specifically for high-reliability industrial data acquisition - integrating signal conditioning, protection, and flexible digital interfacing to simplify system-level design while maintaining 18-bit accuracy across extended temperature ranges.

FAQ

What is the maximum sampling rate of the ADS8691IPWR?

The ADS8691IPWR achieves a maximum throughput rate of 1 million samples per second (1 MSPS) under recommended operating conditions (AVDD = 5 V, DVDD = 3.3 V). This is enabled by its 665-ns conversion time and 335-ns acquisition time, allowing full 18-bit resolution at high speed without pipeline latency - a key differentiator versus slower variants like the ADS8695 (500 kSPS) and ADS8699 (100 kSPS) in the same family. The ADS8691IPWR maintains this rate across all supported input ranges.

Does the ADS8691IPWR require an external reference voltage?

No, the ADS8691IPWR includes a fully integrated 4.096-V reference with low temperature drift (4–7 ppm/°C) and dedicated REFCAP/REFIO pins for decoupling. While it supports external reference operation via the REFIO pin (4.046–4.146 V range), the on-chip reference eliminates the need for external components in most applications - reducing BOM cost, PCB area, and calibration complexity. When using the internal reference, a 10-μF capacitor on REFCAP is mandatory for stable ADC performance.

How does the programmable input range work on the ADS8691IPWR?

The ADS8691IPWR supports nine software-configurable 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) - selected by writing to internal configuration registers via SPI. Gain and offset errors are factory-trimmed per range, ensuring dc accuracy without recalibration. The constant ≥1 MΩ input impedance across all ranges prevents loading effects, making it suitable for high-impedance sensor interfaces.

What protection features does the ADS8691IPWR offer against input overvoltage?

The ADS8691IPWR provides integrated input overvoltage protection rated for ±20 V on AIN_P and AIN_GND when AVDD = 5 V, and ±15 V when AVDD is floating - exceeding typical industrial IEC 61000-4-5 surge requirements. This protection is implemented within the analog front-end and does not rely on external components. Combined with its constant high input impedance and ±20-V absolute maximum rating, it enables direct connection to field wiring without external TVS diodes or series resistors in many applications.

Can multiple ADS8691IPWR devices be connected in a daisy-chain configuration?

Yes, the ADS8691IPWR supports multiSPI™ daisy-chain operation using its dual SDO outputs (SDO-0 and SDO-1). In daisy-chain mode, SDI of the first device connects to the host, SDO-0 feeds SDI of the next device, and SDO-1 of the last device returns aggregated data - enabling synchronized multi-channel acquisition with minimal host interface resources. This mode is configured via register settings and maintains full 18-bit resolution and timing determinism across all chained devices.