FEATURES

24 Bits, No Missing Codes

? All Data Rates and PGA Settings

Up to 23 Bits Noise-Free Resolution

±0.0010% Nonlinearity (max)

Data Output Rates to 30kSPS

Fast Channel Cycling

? 18.6 Bits Noise-Free (21.3 Effective Bits)

at 1.45kHz

One-Shot Conversions with Single-Cycle

Settling

Flexible Input Multiplexer with Sensor Detect

? Four Differential Inputs (ADS1256 only)

? Eight Single-Ended Inputs (ADS1256 only)

Chopper-Stabilized Input Buffer

Low-Noise PGA: 27nV Input-Referred Noise

Self and System Calibration for All PGA

Settings

5V Tolerant SPI?-Compatible Serial Interface

Analog Supply: 5V

Digital Supply: 1.8V to 3.6V

Power Dissipation

? As Low as 38mW in Normal Mode

? 0.4mW in Standby Mode

APPLICATIONS

Scientific Instrumentation

Industrial Process Control

Medical Equipment

Test and Measurement

Weigh Scales

DESCRIPTION

The ADS1255 and ADS1256 are extremely low-noise,

24-bit analog-to-digital (A/D) converters. They provide

complete high-resolution measurement solutions for the

most demanding applications.

The converter is comprised of a 4th-order, delta-sigma

(ΔΣ) modulator followed by a programmable digital filter. A

flexible input multiplexer handles differential or

single-ended signals and includes circuitry to verify the

integrity of the external sensor connected to the inputs.

The selectable input buffer greatly increases the input

impedance and the low-noise programmable gain

amplifier (PGA) provides gains from 1 to 64 in binary steps.

The programmable filter allows the user to optimize

between a resolution of up to 23 bits noise-free and a data

rate of up to 30k samples per second (SPS). The

converters offer fast channel cycling for measuring

multiplexed inputs and can also perform one-shot

conversions that settle in just a single cycle.

Communication is handled over an SPI-compatible serial

interface that can operate with a 2-wire connection.

Onboard calibration supports both self and system

correction of offset and gain errors for all the PGA settings.

Bidirectional digital I/Os and a programmable clock output

driver are provided for general use. The ADS1255 is

packaged in an SSOP-20, and the ADS1256 in an

SSOP-28.