24-Bit, 30kSPS, Very-Low-Noise Delta-Sigma ADC

24-Bit, 30kSPS, Very-Low-Noise Delta-Sigma ADC - ADS1255


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 resolution of up to 23 bits noise-free and 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.


  • 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

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Parametrics Compare all products in Precision ADCs (<=10MSPS)

Resolution (Bits)
Sample Rate (Max) (kSPS)
# Input Channels
Operating Temperature Range (C)
Package Group
Approx. Price (US$)
Power Consumption (Typ) (mW)
Package Size: mm2:W x L (PKG)
Input Type
Multi-Channel Configuration
Reference Mode
Input Range (Max) (V)
Input Range (Min) (V)
Analog Voltage AVDD (Min) (V)
Analog Voltage AVDD (Max) (V)
Digital Supply (Min) (V)
Digital Supply (Max) (V)
Sample Rate (Max) (MSPS)
ADS1255 ADS1256 ADS1257
24    24    24   
30    30    30   
2    8    4   
SPI    SPI    SPI   
-40 to 85    -40 to 85    -40 to 85   
6.96 | 1ku    7.81 | 1ku    7.65 | 1ku   
36    36    38   
20SSOP: 56 mm2: 7.8 x 7.2(SSOP)    28SSOP: 54 mm2: 5.3 x 10.2(SSOP)    20VQFN: 25 mm2: 5 x 5(VQFN)   
Delta-Sigma    Delta-Sigma    Delta-Sigma   
Multiplexed    Multiplexed    Multiplexed   
Ext    Ext    Ext   
50/60 Hz Rejection
50/60 Hz Rejection
50/60 Hz Rejection
5.25    5.25    5.25   
0    0    0   
4.75    4.75    4.75   
5.25    5.25    5.25   
1.8    1.8    1.8   
3.6    3.6    3.6   
0.03    0.03    0.03