Texas Instruments ADS1254E

Overview

ADS1254E from Texas Instruments is a 24-bit delta-sigma analog-to-digital converter (ADC) with no missing codes, 19-bit effective resolution at 20.8kHz data rate, 1.8ppm rms noise, four differential input channels, and ±15ppm INL. It operates with separate 5V analog and 1.8–3.6V digital supplies, enabling high-precision signal acquisition in low-power industrial measurement systems.

For engineers reviewing the ADS1254E datasheet, ADS1254E pinout, ADS1254E application, or ADS1254E equivalent, key selection considerations include its 24-bit no-missing-codes performance, flexible channel multiplexing via CHSEL0/CHSEL1, synchronous two-wire serial interface for isolated designs, and support for external reference voltages from 0.5V to 5V with 32µA typical load current.

Technical Context

The ADS1254E employs a fourth-order delta-sigma modulator with fixed 64× oversampling ratio and a Sinc5 digital filter, delivering 20.8kHz maximum output rate and 4.24kHz –3dB bandwidth when CLK = 8MHz. Its fully differential switched-capacitor input architecture achieves 102dB CMR at 60Hz and 88dB PSRR, supporting bipolar input configurations via external op-amp circuitry.

Channel selection is controlled by CHSEL0/CHSEL1 pins, enabling discrete selection of four differential pairs (CH1–CH4); internal logic resets conversion on falling CLK edge after channel change, requiring five full conversions (1920 system clocks) for full digital filter settling. The DOUT/DRDY pin alternates between DRDY assertion and MSB-first 24-bit Offset Two's Complement data output, synchronized to externally supplied SCLK independent of system CLK.

Key Specifications

Pinout & Package

ADS1254E is housed in a 20-pin SSOP package with exposed pad (not electrically connected), optimized for compact PCB layout and thermal dissipation in measurement front-ends.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS1255IPW and AD7730BRUZ, the ADS1254E uniquely combines hardware-multiplexed differential inputs, dual-supply digital interface, and wide reference voltage range-making it optimal for multi-sensor, low-power, isolated measurement systems where layout simplicity and supply versatility are critical.

Availability

ADS1254E is available at Aetrix Electronics and suitable for cardiac diagnostics equipment, chromatography analyzers, and industrial process controllers requiring stable component supply across long product lifecycles and rigorous qualification programs.

Supply support for ADS1254E 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 acquisition and industrial signal chain solutions.

The ADS1254E belongs to TI's high-accuracy delta-sigma ADC product line, designed specifically for applications demanding 24-bit integrity, low power, and robust noise immunity in harsh electrical environments such as medical instrumentation and process automation.

FAQ

What is the maximum data rate achievable with the ADS1254E, and what conditions are required?

The ADS1254E achieves a maximum data rate of 20.8kHz when operated with an 8MHz system clock (CLK) and 4.096V reference voltage. This rate is derived from a fixed 64× oversampling ratio and fourth-order delta-sigma modulation. Higher CLK frequencies are not supported; exceeding 8MHz violates absolute maximum ratings and risks timing violation or permanent damage.

How does the ADS1254E handle channel switching between differential inputs?

The ADS1254E uses CHSEL0 and CHSEL1 pins to select one of four differential input pairs (CH1–CH4). A falling edge on CLK after changing these pins triggers internal reset and five full conversions (1920 CLK cycles) for complete digital filter settling. Valid data appears on DOUT/DRDY after this period, ensuring accurate cross-channel measurements without residual settling error.

Can the ADS1254E operate with a 3.3V digital supply, and what are the implications?

Yes, the ADS1254E supports DVDD from 1.8V to 3.6V, including 3.3V. At 3.3V, digital I/O thresholds scale accordingly (VIH = 2.15V min, VOL = 0.4V max), maintaining compatibility with standard 3.3V MCUs. Power consumption increases slightly versus 1.8V operation, but noise immunity improves due to larger logic swing - critical in electrically noisy industrial settings.

What is the purpose of the DOUT/DRDY pin's dual-mode operation on the ADS1254E?

The DOUT/DRDY pin serves two time-multiplexed functions: first asserting LOW to signal valid data in DRDY mode, then shifting out the 24-bit result MSB-first in DOUT mode. This eliminates need for separate control lines, simplifying isolation design. Data format is Offset Two's Complement (e.g., +FS = 0x7FFFFF, zero = 0x000000), requiring proper interpretation in host firmware.

Does the ADS1254E support bipolar input ranges, and how is this implemented?

Yes, the ADS1254E supports bipolar inputs (e.g., ±2.5V, ±5V, ±10V) using an external three-op-amp level-shifting circuit referenced to VREF, as shown in Figure 2 of the datasheet. The device itself accepts only unipolar differential inputs (AGND to AVDD), so external conditioning is mandatory to map bipolar signals into its valid input range without violating rail constraints.