ADS1256IDB TQFP -64 Flash Programmable IC Chips CMOS , 125 MHz Complete DDS Synthesizer

ADS1256IDB

Very Low Noise, 24-Bit Analog-to-Digital Converter

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

ABSOLUTE MAXIMUM RATINGS

AVDD to AGND −0.3 to +6 V

DVDD to DGND −0.3 to +3.6 V

AGND to DGND −0.3 to +0.3 V

Input Current 100, Momentary mA 10,

Continuous mA Analog inputs to AGND −0.3 to AVDD + 0.3 V

Digital inputs DIN, SCLK, CS, RESET, SYNC/PDWN, XTAL1/CLKIN to DGND −0.3 to +6 V

inputs D0/CLKOUT, D1, D2, D3 to DGND −0.3 to DVDD + 0.3 V

Maximum Junction Temperature +150 °C

Operating Temperature Range −40 to +105 °C

Storage Temperature Range −60 to +150 °C

Lead Temperature (soldering, 10s) +300 °C

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 (∆Σ) 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.

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