ZHCSEA6B September   2015  – April 2016 ADS1257

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 修订历史记录
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information
    5. 7.5  Electrical Characteristics
    6. 7.6  Serial Interface Timing Requirements
    7. 7.7  Serial Interface Switching Characteristics
    8. 7.8  RESET and SYNC/PWDN Timing Requirements
    9. 7.9  SCLK Reset Timing Requirements
    10. 7.10 DRDY Update Timing Characteristics
    11. 7.11 Typical Characteristics
  8. 8 Parameter Measurement Information
    1. 8.1 Noise Performance
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1  Input Multiplexer
      2. 9.3.2  Analog Input Buffer
      3. 9.3.3  Programmable Gain Amplifier (PGA)
      4. 9.3.4  Modulator Input Circuitry
      5. 9.3.5  Voltage Reference Inputs (REFP, REFN)
      6. 9.3.6  Clock Input (CLKIN)
      7. 9.3.7  Clock Output (D0/CLKOUT)
      8. 9.3.8  General-Purpose Digital I/O (D0, D1)
      9. 9.3.9  Open- and Short-Circuit Sensor Detection
      10. 9.3.10 Digital Filter
        1. 9.3.10.1 Frequency Response
        2. 9.3.10.2 50-Hz and 60-Hz, Line Cycle Rejection
        3. 9.3.10.3 Settling Time
    4. 9.4 Device Functional Modes
      1. 9.4.1 Power-Up
      2. 9.4.2 Reset
      3. 9.4.3 Standby Mode
      4. 9.4.4 Power-Down Mode
      5. 9.4.5 Conversion Control and Synchronization
        1. 9.4.5.1 Settling Time Using Synchronization
        2. 9.4.5.2 Settling Time Using Single-Shot Mode
        3. 9.4.5.3 Settling Time Using the Input Multiplexer
        4. 9.4.5.4 Settling Time while Continuously Converting
      6. 9.4.6 Calibration
        1. 9.4.6.1 Self-Calibration
          1. 9.4.6.1.1 SELFOCAL Command: Self-Offset Calibration
          2. 9.4.6.1.2 SELFGCAL Command: Self-Gain Calibration
          3. 9.4.6.1.3 SELFCAL Command: Self-Offset and Self-Gain Calibration
        2. 9.4.6.2 System Calibration
          1. 9.4.6.2.1 SYSOCAL Command: System-Offset Calibration
          2. 9.4.6.2.2 SYSGCAL Command: System-Gain Calibration
        3. 9.4.6.3 Auto-Calibration
    5. 9.5 Programming
      1. 9.5.1 Serial Interface
        1. 9.5.1.1 Chip Select (CS)
        2. 9.5.1.2 Serial Clock (SCLK)
        3. 9.5.1.3 Data Input (DIN) and Data Output (DOUT)
        4. 9.5.1.4 Data Ready (DRDY)
      2. 9.5.2 Data Format
      3. 9.5.3 Command Definitions
        1. 9.5.3.1  WAKEUP/NOP: Complete Synchronization or Exit Standby Mode
        2. 9.5.3.2  RDATA: Read Data
        3. 9.5.3.3  RDATAC: Read Data Continuous
        4. 9.5.3.4  SDATAC: Stop Read Data Continuous
        5. 9.5.3.5  RREG: Read from Registers
        6. 9.5.3.6  WREG: Write to Register
        7. 9.5.3.7  SELFCAL: Self-Offset and Self-Gain Calibration
        8. 9.5.3.8  SELFOCAL: Self Offset Calibration
        9. 9.5.3.9  SELFGCAL: Self Gain Calibration
        10. 9.5.3.10 SYSOCAL: System Offset Calibration
        11. 9.5.3.11 SYSGCAL: System Gain Calibration
        12. 9.5.3.12 STANDBY: Standby Mode / Single-shot Mode
        13. 9.5.3.13 RESET: Reset Registers to Default Values
        14. 9.5.3.14 SYNC: Synchronize the Analog-to-Digital Conversion
    6. 9.6 Register Map
      1. 9.6.1  STATUS: Status Register (address = 00h) [reset = x1h]
      2. 9.6.2  MUX : Input Multiplexer Control Register (address = 01h) [reset = 01h]
      3. 9.6.3  ADCON: ADC Control Register (address = 02h) [reset = 20h]
      4. 9.6.4  DRATE: ADC Data Rate Register (address = 03h) [reset = F0h]
      5. 9.6.5  IO: GPIO Control Register (address = 04h) [reset = E0h]
      6. 9.6.6  OFC0: Offset Calibration Register 0 (address = 05h) [reset = depends on calibration results]
      7. 9.6.7  OFC1: Offset Calibration Register 1 (address = 06h) [reset = depends on calibration results]
      8. 9.6.8  OFC2: Offset Calibration Register 2 (address = 07h) [reset = depends on calibration results]
      9. 9.6.9  FSC0: Full-Scale Calibration Register 0 (address = 08h) [reset = depends on calibration results]
      10. 9.6.10 FSC1: Full-Scale Calibration Register 1 (address = 09h) [reset = depends on calibration results]
      11. 9.6.11 FSC2: Full-Scale Calibration Register 2 (address = 0Ah) [reset = depends on calibration results]
  10. 10Applications and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Basic Connections
      2. 10.1.2 Digital Interface Connections
      3. 10.1.3 Analog Input Filtering
      4. 10.1.4 External Reference
      5. 10.1.5 Isolated (or Floating) Sensor Inputs
      6. 10.1.6 Unused Inputs and Outputs
      7. 10.1.7 Pseudo Code Example
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Detailed Design Procedure for ±10-V Input
          1. 10.2.2.1.1 Absolute Input Voltage Range
          2. 10.2.2.1.2 Differential Input Voltage Range
          3. 10.2.2.1.3 Level-Shifted Resistor Divider Sizing
          4. 10.2.2.1.4 Input Filtering
          5. 10.2.2.1.5 Register Settings for ±10-V Input
          6. 10.2.2.1.6 Voltage Input Design Variations
        2. 10.2.2.2 Detailed Design Procedure for 4-mA to 20-mA Input
          1. 10.2.2.2.1 PGA Gain Selection
          2. 10.2.2.2.2 Current-Sense Resistor Sizing
          3. 10.2.2.2.3 Register Settings for 4-mA to 20-mA Input
          4. 10.2.2.2.4 Current Input Design Variations
      3. 10.2.3 Application Curves
    3. 10.3 Dos and Don'ts
  11. 11Power Supply Recommendations
    1. 11.1 Power-Supply Sequencing
    2. 11.2 Power-Supply Decoupling
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13器件和文档支持
    1. 13.1 文档支持
      1. 13.1.1 相关文档
    2. 13.2 社区资源
    3. 13.3 商标
    4. 13.4 静电放电警告
    5. 13.5 Glossary
  14. 14机械、封装和可订购信息

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)
订购信息

1 特性

  • 无噪声分辨率高达 23 位
  • 小型 5mm × 5mm 超薄型四方扁平无引线 (VQFN) 封装
  • 四路模拟输入
    • 双路差分测量或三路单端测量
  • 出色的直流性能
    • 偏移漂移：4nV/°C（增益 = 64）
    • 增益漂移：0.8ppm/°C
    • 非线性：3ppm（增益 = 1）
  • 可编程数据输速率：2.5SPS 至 30kSPS
  • 单周期稳定转换 (≤ 1000SPS)
  • 50Hz 和 60Hz 干扰抑制
  • 高阻抗输入缓冲器
  • 差分输入可编程增益放大器 (PGA)
  • 集成传感器中断检测
  • 2 个通用输入/输出
  • 电源：
    • 模拟电源：5V
    • 数字电源：1.8V 至 3.6V
  • 5V 耐压 串行外设接口 (SPI)™- 兼容串口

2 应用

  • 工厂自动化和过程控制
  • 测试和测量
  • 医疗设备
  • 科学仪表

3 说明

ADS1257 是一款低噪声、30kSPS、24 位、Δ-Σ 模数转换器 (ADC)。该器件采用小型 5mm × 5mm 20 引脚超薄四方扁平无引线 (VQFN) 封装，其中包含一个集成多路复用器 (mux)、输入缓冲器以及可编程增益放大器 (PGA)。该器件将集成度、高转换速率以及 24 位分辨率在小型封装内相结合，使其成为空间受限型应用的 理想选择。

输入多路复用器支持双路差分输入测量或三路单端输入测量。传感器断路检测电路可验证 ADC 输入连接的持续性。可选输入缓冲器大幅提升了输入阻抗，并且在许多情况下免除了对于外部缓冲器的需求。缓冲器输入电压范围包括了模拟接地 (AGND)。低噪声 PGA 针对宽范围输入信号提供的增益值范围为 1 至 64。。可编程数字滤波器可优化 ADC 分辨率（最高可达 23 位的无噪声分辨率）和转换速率（最高可达 30kSPS）。数字滤波器可提供单周期稳定转换以及 50Hz 和 60Hz 干扰信号抑制功能。

兼容串行外设接口 (SPI) 的串行接口最低以三线制即可正常运行，能够简化与外部控制器的连接。集成的校准 特性 支持对所有 PGA 增益设置的偏移和增益误差进行自校正和系统校正。两个双向数字 I/O 引脚控制外部电路。

器件信息(1)

器件型号 封装 封装尺寸（标称值）
ADS1257 超薄四方扁平无引线封装 (VQFN) (20) 5.00mm x 5.00mm
  1. 要了解所有可用封装，请参见数据表末尾的封装选项附录。

方框图

ADS1257 pg1_fbd_bas656.gif

输出数据直方图
（256 项读数，2.5SPS，增益 = 1）

ADS1257 tc_histo_noise_pga1_25sps_bas656.gif