Texas Instruments ADS8684IDBTR

Overview

ADS8684IDBTR from Texas Instruments is a 16-bit, 4-channel, single-supply SAR analog-to-digital converter with integrated analog front-end, ±10.24 V bipolar input range support, 500-kSPS aggregate throughput, and on-chip 4.096-V reference. It serves as a precision data acquisition IC in industrial PLC analog input modules requiring channel-independent programmable ranges and ±20 V overvoltage protection.

For engineers reviewing the ADS8684IDBTR datasheet, ADS8684IDBTR pinout, ADS8684IDBTR application, or ADS8684IDBTR equivalent, key selection criteria include its 1-MΩ constant input impedance across all ranges, daisy-chain SPI interface, –40°C to 125°C operating temperature, and TSSOP-38 package compatibility with high-density industrial PCB layouts.

Technical Context

The ADS8684IDBTR integrates a successive approximation register (SAR) ADC core with per-channel programmable gain amplifiers (PGAs), 2nd-order LPF, OVP circuitry, and a multiplexer supporting both auto-scan and manual channel selection modes. Its analog front-end delivers true bipolar/unipolar input flexibility via software-configurable Range_CHn[3:0] registers.

It operates from a single 5-V analog supply (AVDD = 4.75–5.25 V) and supports 1.65–3.3-V digital I/O (DVDD), enabling direct interfacing with low-voltage microcontrollers. The internal 4.096-V reference exhibits ≤10 ppm/°C drift and is decoupled via REFCAP and REFGND pins.

Key Specifications

Pinout & Package

TSSOP-38 package (9.7 mm × 4.4 mm), thermally enhanced with 28 AGND/AVDD/DGND pins for low-noise analog/digital separation and robust ESD performance (±6 kV HBM on analog inputs).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS8688IPWR and AD7606C-4BSTZ, the ADS8684IDBTR provides optimal balance of integration (on-chip reference, OVP, PGA), compact TSSOP-38 packaging, and SPI daisy-chain scalability - making it ideal for space-constrained, multi-node industrial data acquisition where 4 channels suffice.

Availability

ADS8684IDBTR 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 ADS8684IDBTR 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 ICs.

The ADS868x product line was designed specifically for ruggedized industrial data acquisition - integrating protection, programmability, and accuracy into a single-chip solution for PLCs, energy meters, and motor drives.

FAQ

What input voltage ranges does the ADS8684IDBTR support?

The ADS8684IDBTR supports five software-programmable input ranges per channel: ±10.24 V, ±5.12 V, ±2.56 V, 0–10.24 V, and 0–5.12 V. These are set independently for each of the four analog input channels using the Range_CHn[3:0] register bits. The device achieves this with an integrated PGA and maintains a constant 1-MΩ input impedance across all ranges, eliminating signal-loading variability. The ADS8684IDBTR's ±20 V overvoltage protection remains active regardless of selected range.

Does the ADS8684IDBTR require an external reference voltage?

No, the ADS8684IDBTR includes a precision on-chip 4.096-V reference with ≤10 ppm/°C temperature drift and 4.095–4.097 V output tolerance at 25°C. When REFSEL is pulled low, REFIO becomes an output delivering this reference, and REFCAP must be decoupled with a 10–22 µF capacitor to REFGND. An external reference can be applied via REFIO only when REFSEL is high, but the ADS86684IDBTR's internal reference meets most industrial accuracy requirements without added components.

How does the daisy-chain SPI interface work on the ADS8684IDBTR?

The ADS8684IDBTR's DAISY pin enables daisy-chain configuration: the SDO of one device connects to the SDI of the next, while all share common CS, SCLK, and REFSEL lines. During serial readback, data from multiple ADS8684IDBTR devices shifts out sequentially through a single SDO line. This reduces host GPIO usage and simplifies routing in multi-ADC systems - especially valuable in modular PLC backplanes or distributed I/O nodes where board space and interconnect density are constrained.

What is the power consumption of the ADS8684IDBTR in active and standby modes?

In active conversion mode at 500 kSPS with AVDD = 5 V and DVDD = 3.3 V, the ADS8684IDBTR draws 8.5–11.5 mA from AVDD and 0.5 mA from DVDD, totaling ~65 mW. In STANDBY mode (RST/PD held low), analog circuitry remains powered but conversion halts, reducing AVDD current to 3–4.5 mA. In full PWR_DN mode, current drops to 3–20 µA - enabling ultra-low-power wake-on-event operation in battery-backed data loggers. All modes retain register contents and reference state unless explicitly reset.

Can the ADS8684IDBTR interface directly with a 1.8-V microcontroller?

Yes, the ADS8684IDBTR supports digital I/O voltages from 1.65 V to 3.3 V on DVDD, making it compatible with 1.8-V microcontrollers. Its digital inputs (CS, SCLK, SDI, DAISY, REFSEL, RST/PD) accept VIH ≥ 0.7×DVDD and VIL ≤ 0.3×DVDD, and outputs (SDO) drive VOH ≥ 0.8×DVDD at 500 µA. No level-shifting circuitry is required - simply tie DVDD to the MCU's 1.8-V supply rail and ensure proper grounding between analog and digital domains to maintain noise immunity.