SBASAW0 February   2024 ADS1288

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Timing Requirements: 1.65V ≤ IOVDD ≤ 1.95V and 2.7V ≤ IOVDD ≤ 3.6V
    7. 5.7 Switching Characteristics: 1.65V ≤ IOVDD ≤ 1.95V and 2.7V ≤ IOVDD ≤ 3.6V
    8. 5.8 Timing Diagrams
    9. 5.9 Typical Characteristics
  7. 6 Parameter Measurement Information
    1. 6.1 Noise Performance
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Analog Input
      2. 7.3.2 PGA and Buffer
        1. 7.3.2.1 Programmable Gain Amplifier (PGA)
        2. 7.3.2.2 Buffer Operation (PGA Bypass)
      3. 7.3.3 Voltage Reference Input
      4. 7.3.4 IOVDD Power Supply
      5. 7.3.5 Modulator
        1. 7.3.5.1 Modulator Overdrive
      6. 7.3.6 Digital Filter
        1. 7.3.6.1 Sinc Filter Section
        2. 7.3.6.2 FIR Filter Section
        3. 7.3.6.3 Group Delay and Step Response
          1. 7.3.6.3.1 Linear Phase Response
          2. 7.3.6.3.2 Minimum Phase Response
        4. 7.3.6.4 HPF Stage
      7. 7.3.7 Clock Input
      8. 7.3.8 GPIO
    4. 7.4 Device Functional Modes
      1. 7.4.1 Power-Down Mode
      2. 7.4.2 Reset
      3. 7.4.3 Synchronization
        1. 7.4.3.1 Pulse-Sync Mode
        2. 7.4.3.2 Continuous-Sync Mode
      4. 7.4.4 Sample Rate Converter
      5. 7.4.5 Offset and Gain Calibration
        1. 7.4.5.1 OFFSET Register
        2. 7.4.5.2 GAIN Register
        3. 7.4.5.3 Calibration Procedure
    5. 7.5 Programming
      1. 7.5.1 Serial Interface
        1. 7.5.1.1 Chip Select (CS)
        2. 7.5.1.2 Serial Clock (SCLK)
        3. 7.5.1.3 Data Input (DIN)
        4. 7.5.1.4 Data Output (DOUT)
        5. 7.5.1.5 Data Ready (DRDY)
      2. 7.5.2 Conversion Data Format
      3. 7.5.3 Commands
        1. 7.5.3.1  Single Byte Command
        2. 7.5.3.2  WAKEUP: Wake Command
        3. 7.5.3.3  STANDBY: Software Power-Down Command
        4. 7.5.3.4  SYNC: Synchronize Command
        5. 7.5.3.5  RESET: Reset Command
        6. 7.5.3.6  Read Data Direct
        7. 7.5.3.7  RDATA: Read Conversion Data Command
        8. 7.5.3.8  RREG: Read Register Command
        9. 7.5.3.9  WREG: Write Register Command
        10. 7.5.3.10 OFSCAL: Offset Calibration Command
        11. 7.5.3.11 GANCAL: Gain Calibration Command
  9. 8 Register Map
    1. 8.1 Register Descriptions
      1. 8.1.1 ID/SYNC: Device ID, SYNC Register (Address = 00h) [Reset = xxxx0010b]
      2. 8.1.2 CONFIG0: Configuration Register 0 (Address = 01h) [Reset = 92h]
      3. 8.1.3 CONFIG1: Configuration Register 1 (Address = 02h) [Reset = 10h]
      4. 8.1.4 HPF0, HPF1: High-Pass Filter Registers (Address = 03h, 04h) [Reset = 32h, 03h]
      5. 8.1.5 OFFSET0, OFFSET1, OFFSET2: Offset Calibration Registers (Address = 05h, 06h, 07h) [Reset = 00h, 00h, 00h]
      6. 8.1.6 GAIN0, GAIN1, GAIN2: Gain Calibration Registers (Address = 08h, 09h, 0Ah) [Reset = 00h, 00h, 40h]
      7. 8.1.7 GPIO: Digital Input/Output Register (Address = 0Bh) [Reset = 000xx000b]
      8. 8.1.8 SRC0, SRC1: Sample Rate Converter Registers (Address = 0Ch, 0Dh) [Reset = 00h, 80h]
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
      1. 9.3.1 Analog Power Supplies
      2. 9.3.2 Digital Power Supply
      3. 9.3.3 Grounds
      4. 9.3.4 Thermal Pad
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.1 Overview

The ADS1288 is a high-resolution, low-power analog-to-digital converter (ADC) designed for applications in energy exploration, geology, and seismic monitoring where low-power consumption and high resolution are required. The output data resolution is 32 bits spanning data rates from 125SPS to 2000SPS. The programmable gain amplifier (PGA) expands the system dynamic range with seven input ranges of ±2.5VPP to ±0.039VPP.

As illustrated in the Functional Block Diagram, the ADC consists of the following sections: input multiplexer (MUX), programmable gain amplifier (PGA), unity-gain buffer, delta-sigma (ΔΣ) modulator, sample rate converter, infinite impulse response (IIR) high-pass filter (HPF), finite impulse response (FIR) low-pass filter (LPF), and an SPI-compatible serial interface used for both device configuration and conversion data readback.

The input multiplexer selects between inputs 1 and 2, and internal options designed for self-test, including an input-short connection to test device offset and noise performance.

The input multiplexer is followed by a low-noise PGA. The range of PGA gains is 1 to 16, with gains 32 and 64 implemented as digital gains. The PGA is chopper-stabilized to reduce 1/f noise and input offset voltage. The PGA output connects to a buffer which drives the modulator. An external 10nF capacitor, connected to PGA output pins CAPP and CAPN, provides an antialias filter for the input signal.

Disable the PGA to lower device power consumption by operating the ADC with the unity-gain buffer. External 47nF capacitors connected to each buffer output filter the modulator sampling pulses.

The ΔΣ modulator measures the differential input signal (VIN) at the PGA output against the differential reference voltage (VREF = 2.5V). Modulator data are processed by the digital filter to provide the final conversion result. The digital filter consists of a sinc filter followed by a programmable phase, FIR low-pass filter, and an IIR high-pass filter. The high-pass filter removes dc and low-frequency components from the data.

The sample rate converter (SRC) compensates clock signal error by resampling the output data to correct the output data rate. Write the desired compensation value to the SRC register for data rate correction with up to 7ppb accuracy.

User-programmable gain and offset calibration registers correct offset and gain errors.

The SYNC pin synchronizes the ADC. Synchronization has two modes of operation: pulse synchronization and continuous synchronization. The RESET pin resets the ADC, including user-configuration settings. The pins are noise-resistant, Schmitt-trigger inputs to increase reliability in high-noise environments.

The PWDN pin powers down the ADC when not in use. The software power-down mode (STANDBY) is available through the serial interface

The 4-wire, SPI-compatible, serial interface reads conversion data and reads or writes device register data.

Two general-purpose digital I/Os are available to control external switches for diagnostic tests.

Power for the PGA and buffer is supplied by pins AVDD1 and AVSS. A charge pump voltage regulator increases the buffer supply voltage to increase input voltage range. Power for the modulator is supplied by the AVDD2 pin. The digital I/O voltage pin (IOVDD) powers the digital logic core through a 1.8V low-dropout regulator (LDO).