Texas Instruments ADS8861IDGSR

Overview

ADS8861IDGSR from Texas Instruments is a 16-bit, 1-MSPS true-differential SAR analog-to-digital converter with no latency output, 96 dB SNR, ±1.0 LSB INL (max), and SPI-compatible serial interface. It operates from 2.7 V to 3.6 V AVDD/DVDD, accepts 2.5 V to 5 V external reference, and delivers 5.5 mW power dissipation at full speed - used in precision medical instrumentation and low-power battery-operated test equipment.

For engineers reviewing the ADS8861IDGSR datasheet, ADS8861IDGSR pinout, ADS8861IDGSR application, or ADS8861IDGSR equivalent, this page provides verified technical context, validated pin functions, confirmed differential input behavior, real-world timing constraints (tACQ = 290 ns, tconv ≤ 710 ns), and two documented alternative parts for signal chain design continuity.

Technical Context

The ADS8861IDGSR implements a charge-redistribution SAR architecture with integrated sample-and-hold, enabling true-differential acquisition across AINP/AINN with common-mode voltage range of 0 V to VREF and ≥90 dB CMRR. Its internal conversion clock drives binary search without external timing dependency.

Digital interface supports three modes: 3-wire (CONVST as CS), 4-wire (DIN as CS), and daisy-chain; all use SCLK-synchronized DOUT with optional busy indicator bit. Power consumption scales linearly with throughput - 55 µW at 10 kSPS, 5.5 mW at 1 MSPS - and device auto-enters 50 nA power-down state post-conversion.

Key Specifications

Pinout & Package

ADS8861IDGSR is packaged in a 10-pin MSOP (DGS) with exposed thermal pad. Pin functions are validated per TI SBAS557A datasheet and match the DGS package pinout.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS8861IDGSR, ADS8860IDGSR removes differential input capability but retains pin compatibility for simpler signal chains, while ADS8865IDRCR trades 1-MSPS speed for enhanced noise performance and identical mechanical fit - both serve distinct trade-off points in TI's 16-bit SAR family.

Availability

ADS8861IDGSR is available at Aetrix Electronics and suitable for precision medical equipment, automated test equipment (ATE), and low-power battery-operated instrumentation requiring stable component supply and long-term production continuity.

Supply support for ADS8861IDGSR 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 company headquartered in Dallas, Texas, specializing in analog, embedded processing, and high-performance silicon solutions for industrial, automotive, and communications markets.

The ADS8861IDGSR belongs to TI's precision SAR ADC product line, designed specifically for high-resolution, low-power, true-differential data acquisition in portable and space-constrained instrumentation systems.

FAQ

What is the maximum sampling rate supported by the ADS8861IDGSR?

The ADS8861IDGSR supports a maximum throughput rate of 1 MSPS (1 million samples per second) with no latency output. This is confirmed in the Electrical Characteristics table under "Maximum throughput rate" with a minimum value of 1000 kHz. At this rate, conversion time is ≤710 ns and acquisition time is fixed at 290 ns, enabling real-time capture of fast transients in test and measurement systems.

Does the ADS8861IDGSR require an external reference voltage, and what is its acceptable range?

Yes, the ADS8861IDGSR requires an external reference voltage applied to the REF pin. Its specified input range is 2.5 V to 5 V, independent of AVDD supply voltage. The device's full-scale differential input span scales directly with VREF (–VREF to +VREF), and linearity performance remains stable across this range - validated by INL/DNL plots in the datasheet Figures 12–13.

How does the true-differential input of the ADS8861IDGSR improve system-level noise immunity?

The ADS8861IDGSR's true-differential input provides ≥90 dB common-mode rejection ratio (CMRR) across dc to 100 kHz, allowing it to suppress noise coupled equally onto AINP and AINN. Unlike pseudo-differential architectures, its common-mode voltage can be set anywhere from 0 V to VREF - enabling direct interface with floating sensors (e.g., bridge transducers) without level-shifting circuitry, thereby preserving SNR and reducing component count.

Can multiple ADS8861IDGSR devices be connected on the same SPI bus, and how is synchronization achieved?

Yes, the ADS8861IDGSR supports daisy-chain operation using a single SCLK, DIN, and DOUT line. Synchronization is achieved by asserting CONVST simultaneously across all devices, triggering concurrent sampling. Data is then shifted out sequentially - first device's MSB appears on DOUT after td-CNV-DO (12.3 ns), followed by subsequent devices' data - enabling time-aligned multi-channel acquisition without additional timing controllers.

What power-saving features does the ADS8861IDGSR implement during idle periods?

The ADS8861IDGSR automatically enters a 50 nA power-down state at the end of every conversion and remains in that state during the acquisition phase. Power consumption scales linearly with throughput: 5.5 mW at 1 MSPS, 0.55 mW at 100 kSPS, and 55 µW at 10 kSPS. This behavior is inherent to its SAR architecture and requires no software command - simplifying low-power firmware design for battery-operated instruments.