SBAU171D May   2010  – January 2016 ADS1198 , ADS1298

 

  1.   ADS1298ECG-FE/ADS1198ECG-FE
    1.     Trademarks
    2. 1 ADS1298ECG-FE/ADS1198ECG-FE Overview
      1. 1.1 Important Disclaimer Information
      2. 1.2 Introduction
      3. 1.3 Supported Features
      4. 1.4 Features Not Supported in Current Version
      5. 1.5 ADS1x98ECG-FE Hardware
      6. 1.6 Minimum System Requirements for ADS1x98ECG-FE Evaluation Software
    3. 2 Quick Start
      1. 2.1 Default Jumper/Switch Configuration
      2. 2.2 ADS1x98ECG-FE Operation
    4. 3 Using the ADS1298ECG-FE Software
      1. 3.1 Application User Menu
      2. 3.2 Top-Level Application Controls
      3. 3.3 About Tab
      4. 3.4 ADC Register Tab
        1. 3.4.1 Standby and Reset Controls
        2. 3.4.2 Channel Registers Tab (ADC Register)
          1. 3.4.2.1 Global Channel Registers
          2. 3.4.2.2 Channel Control Registers
        3. 3.4.3 LOFF and RLD Tab (ADC Register)
          1. 3.4.3.1 Lead-Off Detection and Current Direction Control Registers
          2. 3.4.3.2 Right Leg Drive Derivation Control Registers
        4. 3.4.4 GPIO and OTHER Registers Tab (ADC Register)
          1. 3.4.4.1 Wilson Central and Augmented Lead Registers
        5. 3.4.5 Register Map (ADC Register)
      5. 3.5 Analysis Tab
        1. 3.5.1 Scope Tab (Anaysis)
          1. 3.5.1.1 Zoom Tool
        2. 3.5.2 Histogram Tab (Analysis)
        3. 3.5.3 FFT Tab
        4. 3.5.4 ECG Tab (Analysis)
      6. 3.6 Save Tab
    5. 4 ADS1x98ECG-FE Input Signals
      1. 4.1 Input Short Testing
      2. 4.2 Internal Test Signals Input
      3. 4.3 Temperature Sensor
      4. 4.4 Normal Electrode Input
        1. 4.4.1 Capturing 12-Lead ECG Signals
      5. 4.5 MVDD Input, RLD Measurement, RLD Positive Electrode Driver, and RLD Negative Electrode Driver
      6. 4.6 Lead Derivation
      7. 4.7 Wilson Center Terminal (WCT)
      8. 4.8 Right Leg Drive
        1. 4.8.1 RLD Common Mode Voltage
        2. 4.8.2 Driving the RLD Cable Shield
      9. 4.9 PACE Detection
    6. 5 ADS1298ECG-FE/ADS1198ECG-FE Hardware Details
      1. 5.1 Jumper Description
      2. 5.2 Power Supply
      3. 5.3 Clock
      4. 5.4 Reference
      5. 5.5 Analog Output Signals
      6. 5.6 Digital Signals
      7. 5.7 Analog Input Signals
        1. 5.7.1 Patient Simulator Input
        2. 5.7.2 Arbitrary Input Signals
  2. ASchematics, BOM, Layout, and ECG Cable Details
    1. A.1 Overview
    2. A.2 ADS1x98ECG-FE Front-End Board Schematics
    3. A.3 Bill of Materials
      1. Table 13. Bill of Materials: ADS1x98ECG-FE
    4. A.4 Printed Circuit Board Layout
    5. A.5 ECG Cable Details
  3. BExternal Optional Hardware
    1. B.1 Optional External Hardware (Not Included)
    2. B.2 ADS1x98ECG-FE Power-Supply Recommendations
  4. CSoftware Installation
    1. C.1 Minimum Requirements
    2. C.2 Installing the Software

3.4.3.1 Lead-Off Detection and Current Direction Control Registers

The first two arrays of controls (Lead Off Sense) enable lead-off detection for both the positive and negative channels, LOFF_SENSP and LOFF_SENSN. By pressing the buttons, lead-off detection is enabled for each channel individually and for each input (positive and negative). Set All LOFFP Bits and Set All LOFFN Bits allow the user to turn on or off all the enable bits at once instead of clicking each individual channel control.

The third array of controls (Lead Off Current Direction) determines the current direction used for lead-off detection when an excitation signal is selected as a pull-up/pull-down resistor. Each channel is controlled individually by selecting the button that corresponds to the desired channel to manipulate. When the button is not illuminated, LOFF_FLIP = 0 (INP is pulled-up to AVDD and INN is pulled-down to ground). When the button is pressed/illuminated, LOFF_FLIP = 1 (INP is pulled-down to ground and INN is pulled-up to AVDD). Further details of these registers and lead-off function are located in the Applications Section of the device data sheet.

Figure 10 describes the mode for Lead-Off Detection (that is, resistive or current source) and the 4-bit DAC settings to configure the lead-off threshold. Figure 13 illustrates the connections from the positive and negative inputs to the lead-off comparators. The output of the comparators is viewed by using Show/Poll Lead Off Status control as described in Section 3.2

ai_loff_config_bau171.gifFigure 13. LOFF_STATP and LOFF_STATN Comparators