Texas Instruments ADS8684AIDBTR

Overview

ADS8684AIDBTR from Texas Instruments is a 16-bit, 4-channel, single-supply SAR analog-to-digital converter with integrated analog front-end, ±20 V input overvoltage protection, 500 kSPS aggregate throughput, and software-programmable bipolar/unipolar input ranges (±10.24 V to ±0.156 V). It serves as the core data acquisition engine in industrial PLC analog input modules.

For engineers reviewing the ADS8684AIDBTR datasheet, ADS8684AIDBTR pinout, ADS8684AIDBTR application, or ADS8684AIDBTR equivalent, key selection criteria include channel-independent gain/offset trimming, constant 1 MΩ input impedance across all ranges, SPI-compatible daisy-chain interface, on-chip 4.096-V reference with 6–10 ppm/°C drift, and operation from –40°C to 125°C.

Technical Context

The ADS8684AIDBTR integrates a successive approximation register (SAR) ADC core with per-channel programmable gain amplifiers (PGA), 4- to 8-channel multiplexer (configured for 4 channels), and input protection circuitry enabling ±20 V fault tolerance. Its analog front-end delivers true bipolar input capability without external level-shifting.

It uses an internal 4.096-V reference with low-drift buffer and supports external reference via REFIO. The digital interface operates at up to 17 MHz SCLK with 1.65–5.25 V I/O compatibility, and features ALARM output with per-channel high/low thresholds plus DAISY chain support for multi-device synchronization.

Key Specifications

Pinout & Package

TSSOP-38 package (9.7 mm × 4.4 mm), thermally enhanced for industrial ambient temperatures up to 125°C. Pinout validated per TI SBAS680 datasheet (Rev. July 2015).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit SAR ADC applications.

Compared with ADS8688AIDBTR, the ADS8684AIDBTR reduces channel count while retaining identical per-channel performance, OVP, and reference integration-ideal for cost-optimized 4-input systems. Versus AD7606BSTZ, it delivers superior integration, lower BOM count, and robust field survivability but trades off parallel interface flexibility.

Availability

ADS8684AIDBTR is available at Aetrix Electronics and suitable for power automation, protection relay, and PLC analog input module designs requiring stable component supply, long-term industrial lifecycle support, and guaranteed traceable sourcing.

Supply support for ADS8684AIDBTR 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 conversion and industrial-grade IC design.

The ADS868xA family was developed specifically for rugged industrial data acquisition, integrating protection, programmability, and precision into a single-chip solution targeting PLCs, energy meters, and protection relays operating from –40°C to 125°C.

FAQ

What input voltage ranges does the ADS8684AIDBTR support?

The ADS8684AIDBTR supports software-programmable bipolar ranges of ±10.24 V, ±5.12 V, ±2.56 V, ±1.28 V, and ±0.64 V, plus unipolar ranges of 0–10.24 V, 0–5.12 V, 0–2.56 V, and 0–1.28 V. Each of its four analog input channels can be independently configured to any supported range, enabling mixed-signal acquisition without external scaling components. The ADS8684AIDBTR achieves this using integrated PGAs trimmed for gain accuracy across all ranges.

Does the ADS8684AIDBTR include overvoltage protection, and what is its rating?

Yes, the ADS8684AIDBTR includes integrated analog input overvoltage protection rated at ±20 V on all AIN pins when AVDD is powered and presents low impedance (<30 kΩ). This protection eliminates the need for external TVS diodes or series resistors in most industrial field-wiring scenarios. The ADS8684AIDBTR also specifies ±11 V OVP under floating AVDD conditions, ensuring robustness during power sequencing or fault events.

How does the ADS8684AIDBTR handle reference voltage generation?

The ADS8684AIDBTR integrates a precision 4.096-V reference with 6–10 ppm/°C temperature drift and 15-ms turn-on time. Reference selection is controlled by the REFSEL pin: when low, REFIO outputs the internal reference; when high, REFIO accepts an external reference (4.046–4.146 V). The ADS8684AIDBTR uses separate REFCAP and REFGND pins to decouple the reference buffer, ensuring stability under dynamic load conditions.

What is the digital interface type and timing capability of the ADS8684AIDBTR?

The ADS8684AIDBTR features an SPI-compatible serial interface supporting clock frequencies up to 17 MHz, with timing parameters validated across –40°C to 125°C. It supports standard 4-wire operation and daisy-chain mode via the DAISY pin for cascading multiple devices on a single SPI bus. The ADS8684AIDBTR also includes an ALARM output that asserts asynchronously when any channel exceeds user-defined thresholds, enabling hardware-triggered fault response.

What is the power consumption profile of the ADS8684AIDBTR in active and standby modes?

In active conversion mode at 500 kSPS with internal reference enabled, the ADS8684AIDBTR draws 8.5–11.5 mA from AVDD (5 V) and 0.5 mA from DVDD (3.3 V), totaling ~65 mW. In standby mode (STDBY), it consumes 3–4.5 mA; in full power-down (PWR_DN), quiescent current drops to 3–20 µA. This scalable power profile allows the ADS8684AIDBTR to support both continuous high-speed acquisition and ultra-low-power battery-operated logging.