Texas Instruments ADS8638SRGER

Overview

ADS8638SRGER from Texas Instruments is a 12-bit, 8-channel, bipolar-input SAR analog-to-digital converter with software-selectable input ranges (±10V, ±5V, ±2.5V, 0–10V, 0–5V), 1MSPS throughput, internal 2.5V reference, temperature sensor, and per-channel digital comparator. It operates across –40°C to +125°C and targets high-precision industrial data acquisition systems requiring wide dynamic range and minimal external components.

For engineers reviewing the ADS8638SRGER datasheet, ADS8638SRGER pinout, ADS8638SRGER application, or ADS8638SRGER equivalent, key selection considerations include its 8-channel multiplexer architecture, HVDD/HVSS high-voltage supply rails (±15V), SPI-compatible serial interface with CS/SCLK/DIN/DOUT, integrated alarm thresholding, and QFN-24 (4mm × 4mm) package with thermal pad.

Technical Context

The ADS8638SRGER employs a successive approximation register (SAR) core with no latency in conversions and a sample-and-hold front-end optimized for bipolar and unipolar inputs up to ±10V. Its 8-channel analog multiplexer supports independent software configuration of input range per channel.

It integrates an internal 2.5V voltage reference (±1.2% initial accuracy, 20ppm/°C drift), a calibrated temperature sensor (±5% FSR accuracy), and a digital comparator with programmable thresholds per channel. Digital I/O operates from 1.65V to 5.25V, enabling direct interfacing with low-voltage microcontrollers.

Key Specifications

Pinout & Package

ADS8638SRGER is housed in a 4mm × 4mm QFN-24 package with exposed thermal pad (RGE suffix). The package supports reflow soldering and provides low thermal resistance (θJA = 32.6°C/W) for sustained 1MSPS operation in industrial ambient conditions.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar analog-to-digital conversion applications.

Compared with ADS8634SRGER and AD7606BSTZ, the ADS8638SRGER uniquely balances 8-channel density, software-flexible input ranges, integrated reference/comparator/temp sensor, and industrial-grade packaging - making it optimal for cost-sensitive, space-constrained, and functionally rich industrial DAQ designs.

Availability

ADS8638SRGER is available at Aetrix Electronics and suitable for industrial process controls (PLC), data acquisition systems, high-speed closed-loop systems, and digital power supplies requiring stable component supply, extended temperature qualification, and long-term production continuity.

Supply support for ADS8638SRGER 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 digital signal processing technologies for industrial, automotive, and communications markets.

The ADS8638SRGER belongs to TI's precision data acquisition portfolio, designed specifically for rugged industrial environments where wide input range, high channel density, and integrated diagnostics reduce system complexity and improve reliability.

FAQ

What input voltage ranges does the ADS8638SRGER support?

The ADS8638SRGER supports five software-selectable input ranges: ±10V, ±5V, ±2.5V, 0–10V, and 0–5V. These ranges are configured per channel via SPI commands, allowing mixed-signal acquisition on a single device. The ±10V range is enabled using the internal 2.5V reference with appropriate gain setting, and up to ±12V is achievable with an external reference. All ranges maintain 12-bit resolution and specified INL/SNR performance across –40°C to +125°C.

How does the ADS8638SRGER handle high-voltage analog inputs?

The ADS8638SRGER uses separate HVDD and HVSS supply pins (±10V to ±15V) to power its internal analog multiplexer, enabling direct connection of ±10V signals without external level-shifting circuitry. The AINGND pin serves as the common-mode reference for all eight analog inputs, ensuring accurate measurement even when sensors are grounded at different potentials. This architecture isolates high-voltage signal paths from the low-voltage analog and digital domains, preserving SNR and preventing latch-up under overvoltage conditions.

Can the ADS8638SRGER operate with a 1.8V digital supply?

Yes, the ADS8638SRGER supports DVDD from 1.65V to 5.25V, including 1.8V operation. At 1.8V DVDD, the SPI interface maintains full functionality with adjusted timing parameters (e.g., minimum SCLK period = 15 SCLK cycles, t_su(DIN-SCLK) = 7.0ns). Digital I/O levels remain CMOS-compatible, and the AL_PD pin retains its dual alarm/power-down function. This enables direct interfacing with ultra-low-power microcontrollers and FPGAs without level translators.

What is the role of the AL_PD pin on the ADS8638SRGER?

The AL_PD pin on the ADS8638SRGER is a multifunction terminal configurable via SPI register: as an active-high digital alarm output indicating when any channel exceeds its programmed threshold, or as an active-low asynchronous power-down input. When used as an alarm output, it features an internal weak pull-up to DVDD; when used as a power-down input, it can be floated (default state). This dual-role capability reduces required GPIO resources in host systems while enabling rapid fault response or low-power sleep modes.

Does the ADS8638SRGER include an internal voltage reference?

Yes, the ADS8638SRGER integrates a 2.5V internal voltage reference with ±1.2% initial accuracy and 20ppm/°C temperature drift. It is enabled by default and decoupled via the REFGND pin. The REF pin serves as both reference output (when internal reference is selected) and reference input (when external reference is used). The internal reference supports all five input ranges and contributes to the device's self-contained architecture - eliminating the need for external reference ICs in most industrial applications.