ADS1256

Part: ADS1256 (also ADS1255) — Texas Instruments

Type: 24-Bit Delta-Sigma Analog-to-Digital Converter

Description: Very low-noise 24-bit delta-sigma ADC with data rates up to 30 kSPS, a 1–64 gain PGA, and an SPI-compatible interface. It offers up to 23 bits of noise-free resolution, runs from a 5 V analog supply, and dissipates 38 mW typical in normal mode.

Operating Conditions:

• Analog supply (AVDD): 4.75–5.25 V
• Digital supply (DVDD): 1.8–3.6 V
• Operating temperature: -40 to +105 °C (specified performance -40 to +85 °C)
• Master clock: 2–10 MHz with a crystal, 0.1–10 MHz with an external oscillator (7.68 MHz typical)
• Reference input voltage: 0.5–2.6 V (2.5 V typical)

Absolute Maximum Ratings:

• AVDD to AGND: -0.3 to +6 V
• DVDD to DGND: -0.3 to +3.6 V
• Analog inputs to AGND: -0.3 to AVDD + 0.3 V
• Input current: 100 mA momentary, 10 mA continuous
• Maximum junction temperature: +150 °C
• Storage temperature: -60 to +150 °C

Key Specs:

• Resolution: 24 bits, no missing codes at all data rates and PGA settings
• Data rate: 2.5 to 30,000 SPS (fCLKIN = 7.68 MHz)
• Integral nonlinearity: ±0.0003% FSR typical, ±0.0010% FSR max (differential input, PGA = 1)
• Input impedance with buffer on: 80 MΩ min (fDATA ≤ 50 Hz)
• Offset drift: ±100 nV/°C (PGA = 1), ±4 nV/°C (PGA = 64)
• Gain drift: ±0.8 ppm/°C (PGA = 1)
• Common-mode rejection: 95 dB min (fCM = 60 Hz, fDATA = 30 kSPS)
• AVDD current, normal mode, buffer off: 7 mA typical (PGA = 1), 16 mA typical (PGA = 64)
• Power dissipation: 38 mW typical in normal mode (PGA = 1, buffer off, DVDD = 3.3 V); 0.4 mW typical in standby
• Power-down current: 2 μA max each on AVDD and DVDD

Features:

• 24 bits, no missing codes
• Up to 23 bits noise-free resolution
• Low-noise PGA with 27 nV input-referred noise
• Gain from 1 to 64 in binary steps
• Four differential or eight single-ended inputs (ADS1256)
• Input multiplexer with sensor detect current sources
• Chopper-stabilized input buffer
• Fast channel cycling and one-shot conversions with single-cycle settling
• Self and system calibration for all PGA settings
• 5 V tolerant SPI-compatible serial interface
• Bidirectional digital I/Os and programmable clock output

Applications:

• Scientific instrumentation
• Industrial process control
• Medical equipment
• Test and measurement
• Weigh scales

Package:

• SSOP-28 (ADS1256)
• SSOP-20 (ADS1255)

• D 24 Bits, No Missing Codes
• -All Data Rates and PGA Settings
• D Up to 23 Bits Noise-Free Resolution
• D ± 0.0010% Nonlinearity (max)
• D Data Output Rates to 30kSPS
• D Fast Channel Cycling
• -18.6 Bits Noise-Free (21.3 Effective Bits) at 1.45kHz
• D One-Shot Conversions with Single-Cycle Settling
• D Flexible Input Multiplexer with Sensor Detect
• -Four Differential Inputs (ADS1256 only)
• -Eight Single-Ended Inputs (ADS1256 only)
• D Chopper-Stabilized Input Buffer
• D Low-Noise PGA: 27nV Input-Referred Noise
• D Self and System Calibration for All PGA Settings
• D 5V Tolerant SPI -Compatible Serial Interface
• D Analog Supply: 5V
• D Digital Supply: 1.8V to 3.6V
• D Power Dissipation
• -As Low as 38mW in Normal Mode
• -0.4mW in Standby Mode

• D Scientific Instrumentation
• D Industrial Process Control
• D Medical Equipment
• D Test and Measurement
• D Weigh Scales

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

SPI is a trademark of Motorola, Inc. All other trademarks are the property of their respective owners.

www.ti.com ADS1256

SBAS288K -JUNE 2003 -REVISED SEPTEMBER 2013

All specifications at -40 ° C to +85 ° C, AVDD = +5V, DVDD = +1.8V, f CLKIN = 7.68MHz, PGA = 1, and V REF = +2.5V, unless otherwise noted.

over operating free-air temperature range unless otherwise noted (1)

(1) Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to absolute maximum conditions for extended periods may degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those specified is not implied.

This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.

ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.

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