Texas Instruments ADS8638SRGET

Overview

ADS8638SRGET from Texas Instruments is a 12-bit, 8-channel, bipolar-input successive approximation register (SAR) analog-to-digital converter with software-selectable input ranges (±10 V, ±5 V, ±2.5 V, 0–10 V, or 0–5 V), 1 MSPS throughput, and integrated temperature sensor, internal 2.5-V reference, and per-channel digital comparator. It operates across –40°C to +125°C and targets industrial process control and high-speed data acquisition systems.

For engineers reviewing the ADS8638SRGET datasheet, ADS8638SRGET pinout, ADS8638SRGET application, or ADS8638SRGET equivalent, key selection considerations include its 8-channel multiplexer architecture, HVDD/HVSS high-voltage supply rails (±15 V), SPI-compatible serial interface, alarm thresholding capability per channel, and QFN-24 package with thermal pad for industrial thermal management.

Technical Context

The ADS8638SRGET uses a true SAR architecture with no latency in conversion, enabling deterministic timing for closed-loop control. Its front-end includes a high-voltage analog multiplexer powered by separate HVDD (10–15 V) and HVSS (–15 to 0 V) supplies, allowing direct measurement of ±10-V signals without external level-shifting circuitry.

It integrates an internal 2.5-V voltage reference (±1.2% initial accuracy, 20 ppm/°C drift), a temperature sensor (±5% FSR accuracy), and programmable per-channel alarm thresholds via SPI. The digital interface supports CMOS logic levels (1.65–5.25 V DVDD), with SCLK up to 20 MHz and full 16-bit frame output including status bits.

Key Specifications

Pinout & Package

ADS8638SRGET is housed in a 4 mm × 4 mm QFN-24 package with exposed thermal pad (RGE suffix), optimized for thermal dissipation in sealed industrial enclosures. Pin 1 is AVDD; pins 2–3 and 20 are AGND/DGND; pin 13 is AIN0; pin 6 is AIN7 - full 8-channel mapping confirmed per TI SBAS541A Figure 2.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-channel, high-voltage SAR ADC applications.

Compared with ADS8634SRGET, the ADS8638SRGET delivers double channel count in identical package size and power envelope; versus AD7606C-16BSTZ, it trades 4-bit resolution for integrated features (reference, temp sensor, comparator), lower power, and deterministic latency - making it optimal for real-time industrial control rather than lab-grade measurement.

Availability

ADS8638SRGET 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 operation, and high-voltage analog input capability.

Supply support for ADS8638SRGET 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 connectivity technologies for industrial, automotive, and communications markets.

The ADS8638SRGET belongs to TI's precision SAR ADC product line, designed specifically for ruggedized industrial data acquisition where high-voltage input, channel density, and on-chip intelligence (alarm, temp sensing) reduce system-level component count and firmware complexity.

FAQ

What input voltage ranges does the ADS8638SRGET support?

The ADS8638SRGET supports five software-selectable input ranges via SPI register configuration: ±10 V, ±5 V, ±2.5 V, 0–10 V, and 0–5 V. These ranges are enabled using the internal 2.5-V reference or an external reference (2.0–3.0 V). The device maintains full 12-bit performance across all ranges and the full –40°C to +125°C temperature range, with no hardware changes required.

How does the ADS8638SRGET handle high-voltage analog inputs up to ±10 V?

The ADS8638SRGET uses dedicated HVDD (10–15 V) and HVSS (–15 to 0 V) supply pins to power its internal analog multiplexer, enabling direct connection of ±10-V signals to AIN0–AIN7 without external level-shifting circuitry. Input common-mode range extends from HVSS to HVDD, and AINGND serves as the input ground sense terminal - ensuring accurate measurement even with floating or non-ground-referenced sensors.

What is the function of the AL_PD pin on the ADS8638SRGET?

The AL_PD pin on the ADS8638SRGET is multifunctional: it can be configured via SPI as either an active-high digital alarm output (indicating threshold violation on any enabled channel) or as an active-low asynchronous power-down input. By default, it operates as a power-down input with an internal weak pull-up to DVDD. This dual-role pin reduces external GPIO requirements and enables immediate fault response without waiting for SPI polling cycles.

Does the ADS8638SRGET require an external voltage reference?

No, the ADS8638SRGET includes an internal 2.5-V voltage reference with ±1.2% initial accuracy and 20 ppm/°C temperature drift, sufficient for most industrial applications. However, it also supports external references between 2.0 V and 3.0 V applied to the REF pin - useful when higher initial accuracy or lower drift is required. The reference source (internal or external) is selected via SPI configuration register.

What is the maximum SPI clock frequency supported by the ADS8638SRGET?

The ADS8638SRGET supports SPI clock (SCLK) frequencies up to 20 MHz across its full DVDD range (1.65–5.25 V), enabling complete 16-bit frame readout in ≤800 ns. At 20 MHz, the device achieves its rated 1-MSPS throughput with minimal interface overhead. Timing parameters including setup/hold times and CS-to-data delays are fully specified in the datasheet for robust timing margin validation in high-noise industrial environments.