SNAS602C FEBRUARY   2013  – December 2014 ADS1293

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Application Diagram
  5. 5 Revision History
  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 Write Timing Requirements
    7. 7.7 Read Timing Requirements
    8. 7.8 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Flexible Routing Switch
      2. 8.3.2  Battery Monitoring
      3. 8.3.3  Test Mode
      4. 8.3.4  Analog Front-End
      5. 8.3.5  Instrumentation Amplifier (INA)
        1. 8.3.5.1 Instrumentation Amplifier Fault Detection
      6. 8.3.6  Sigma-Delta Modulator (SDM)
        1. 8.3.6.1 Sigma-Delta Modulator Fault Detection
      7. 8.3.7  Programmable Digital Filters
      8. 8.3.8  Filter Settling Time
      9. 8.3.9  Analog Pace Channel
      10. 8.3.10 Wilson Reference
        1. 8.3.10.1 Wilson Central Terminal
        2. 8.3.10.2 Goldberger Terminals
      11. 8.3.11 Common-Mode (CM) Detector
        1. 8.3.11.1 Cable Shield Driving
        2. 8.3.11.2 Common-Mode Output Range (CMOR)
      12. 8.3.12 Right-Leg Drive (RLD)
      13. 8.3.13 Capacitive Load Driving
      14. 8.3.14 Error Status: RLD Rail
      15. 8.3.15 Lead-Off Detection (LOD)
      16. 8.3.16 DC Lead-Off Detect
      17. 8.3.17 Analog AC Lead-Off Detect
      18. 8.3.18 Digital AC Lead-Off Detect
      19. 8.3.19 Clock Oscillator
      20. 8.3.20 Synchronization
      21. 8.3.21 Single-Chip Multi-Channel Synchronization
      22. 8.3.22 Multichip Synchronization
      23. 8.3.23 Synchronization Errors
      24. 8.3.24 Alarm Functions
      25. 8.3.25 Error Filtering
      26. 8.3.26 ALARMB Pin and Error Masking
      27. 8.3.27 Error Register Automatic Clearing Description
      28. 8.3.28 Alarm Propagation
      29. 8.3.29 Reference Voltage Generators
      30. 8.3.30 Power Management
    4. 8.4 Device Functional Modes
      1. 8.4.1 Low Sampling Rate
      2. 8.4.2 High Sampling Rate
      3. 8.4.3 Ouput Code (ADCOUT)
    5. 8.5 Programming
      1. 8.5.1 Serial Digital Interface
      2. 8.5.2 Digital Output Drive Strength
      3. 8.5.3 SPI Protocol
      4. 8.5.4 Random Register Access Protocol
      5. 8.5.5 Auto-Incrementing Address
      6. 8.5.6 Streaming
      7. 8.5.7 Data Ready Bar
      8. 8.5.8 Simultaneous ECG and Pace Data Read
    6. 8.6 Register Maps
      1. 8.6.1  Operation Mode Registers
      2. 8.6.2  Input Channel Selection Registers
      3. 8.6.3  Lead-Off Detect Control Registers
      4. 8.6.4  Common-Mode Detection and Right-Leg Drive Common-Mode Feedback Control Registers
      5. 8.6.5  Wilson Control Registers
      6. 8.6.6  Reference Registers
      7. 8.6.7  OSC Control Registers
      8. 8.6.8  AFE Control Registers
      9. 8.6.9  Error Status Registers
      10. 8.6.10 Digital Registers
      11. 8.6.11 Pace and ECG Data Read Back Registers
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 3-Lead ECG Application
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curves
      2. 9.2.2 5-Lead ECG Application
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
      3. 9.2.3 8- or 12-Lead ECG Application
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
        3. 9.2.3.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Trademarks
    2. 12.2 Electrostatic Discharge Caution
    3. 12.3 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

9.1 Application Information

The ADS1293 is an AFE for biopotential measurements. The device is typically used in portable, low-power medical, sports, and fitness ECG applications. The device's flexibility and synchronization features allows it to be used it in configurations that range from single-chip/single-channel applications to multi-chip/multi-channel applications. The following sections will explore the use model in some of these configurations.

9.2 Typical Applications

9.2.1 3-Lead ECG Application

In the 3-Lead ECG example shown in Figure 84, the right-arm (RA), left-arm (LA), left-leg (LL) and right-leg (RL) electrodes are connected to the IN1, IN2, IN3 and IN4 pins. The ADS1293 uses the Common-Mode Detector to measure the common-mode of the system by averaging the voltage of input pins IN1, IN2 and IN3, and uses this signal in the right-leg drive feedback circuit

(1) The ideal values of R1, R2 and C1 will vary per system / application; typical values for these components are: R1 = 100 kΩ, R2 = 1 MΩ and C1 = 1.5 nF.
. The output of the RLD amplifier is connected to RL through IN4 to drive the common-mode of the system. The chip uses an external 4.096-MHz crystal oscillator connected between the XTAL1 and XTAL2 pins to create the clock source for the device.

3lead_ecg_application_nas602.gifFigure 84. 3-Lead ECG Application

9.2.1.1 Design Requirements

For this design example, use the parameters listed in Table 12 as the set-up parameters.

Table 12. Design Parameters

DESIGN PARAMETER EXAMPLE VALUE
Number of electrodes 4
Lead I definition LA – RA
Lead II definition LL –RA
Bandwidth 175 Hz
Output data rate 853 sps
Analog supply voltage 5.0 V
Digital I/O supply voltage 3.3 V

9.2.1.2 Detailed Design Procedure

Follow the next steps to configure the device for this example, starting from default registers values.

  1. Set address 0x01 = 0x11: Connect channel 1’s INP to IN2 and INN to IN1.
  2. Set address 0x02 = 0x19: Connect channel 2’s INP to IN3 and INN to IN1.
  3. Set address 0x0A = 0x07: Enable the common-mode detector on input pins IN1, IN2 and IN3.
  4. Set address 0x0C = 0x04: Connect the output of the RLD amplifier internally to pin IN4.
  5. Set address 0x12 = 0x04: Use external crystal and feed the internal oscillator's output to the digital.
  6. Set address 0x14 = 0x24: Shuts down unused channel 3’s signal path.
  7. Set address 0x21 = 0x02: Configures the R2 decimation rate as 5 for all channels.
  8. Set address 0x22 = 0x02: Configures the R3 decimation rate as 6 for channel 1.
  9. Set address 0x23 = 0x02: Configures the R3 decimation rate as 6 for channel 2.
  10. Set address 0x27 = 0x08: Configures the DRDYB source to channel 1 ECG (or fastest channel).
  11. Set address 0x2F = 0x30: Enables channel 1 ECG and channel 2 ECG for loop read-back mode.
  12. Set address 0x00 = 0x01: Starts data conversion.

Follow the description in the Streaming section to read the data. The ADS1293 will measure lead I and lead II. Lead III can be calculated as follows: Lead III = Lead II – Lead I

Optionally, the third channel could be used to measure Lead III.

9.2.1.3 Application Curves

Figure 85 show measurement data collected by a single ADS1293 device connected to an ECG simulator configured to produce an ECG signals at a rate of 60 per minute and with an amplitude of 2 mV. The data was collected simultaneously by channels 1 and 2 of the device during a period of 10 seconds.

Ex1_Lead_I_capture.png
Ex1_Lead_II_capture.pngFigure 85. Single ADS1293 Device With an ECG Simulator, CH1 and CH2: ECG Signals

9.2.2 5-Lead ECG Application

In the 5-Lead ECG example shown in Figure 86, the ADS1293 uses the Common-Mode Detector to measure the common-mode of the system by averaging the voltage of input pins IN1, IN2 and IN3, and uses this signal in the right-leg drive feedback circuit

(2) The ideal values of R1, R2 and C1 will vary per system / application; typical values for these components are: R1 = 100 kΩ, R2 = 1 MΩ and C1 = 1.5 nF.
. The output of the RLD amplifier is connected to RL through IN4 to drive the common-mode of the system. The Wilson Central Terminal is generated by the ADS1293 and is used as a reference to measure the chest electrode, V1. The chip uses an external 4.096 MHz crystal oscillator connected between the XTAL1 and XTAL2 pins to create the clock source for the device.

5_lead_example_nas602.gifFigure 86. 5-Lead ECG Application

9.2.2.1 Design Requirements

For this design example, use the parameters listed in Table 13 as the setup parameters.

Table 13. Design Parameters

DESIGN PARAMETER EXAMPLE VALUE
Number of electrodes 5
Lead I definition LA – RA
Lead II definition LL –RA
Lead V definition V1 – WCT
Bandwidth 175 Hz
Output data rate 853 sps
Analog supply voltage 5.0 V
Digital I/O supply voltage 3.3 V

9.2.2.2 Detailed Design Procedure

The following steps configure the ADS1293 for a 5-lead application with an ECG bandwidth of 175 Hz and an output data rate of 853 Hz; it is assumed that the device registers contain their default power-up values.

  1. Set address 0x01 = 0x11: Connects channel 1’s INP to IN2 and INN to IN1.
  2. Set address 0x02 = 0x19: Connect channel 2’s INP to IN3 and INN to IN1.
  3. Set address 0x03 = 0x2E: Connects channel 3’s INP to IN5 and INN to IN6.
  4. Set address 0x0A = 0x07: Enables the common-mode detector on input pins IN1, IN2 and IN3.
  5. Set address 0x0C = 0x04: Connects the output of the RLD amplifier internally to pin IN4.
  6. Set addresses 0x0D = 0x01, 0x0E = 0x02, 0x0F = 0x03: Connects the first buffer of the Wilson reference to the IN1 pin, the second buffer to the IN2 pin, and the third buffer to the IN3 pin.
  7. Set address 0x10 = 0x01: Connects the output of the Wilson reference internally to IN6.
  8. Set address 0x12 = 0x04: Uses external crystal and feeds the output of the internal oscillator module to the digital.
  9. Set address 0x21 = 0x02: Configures the R2 decimation rate as 5 for all channels.
  10. Set address 0x22 = 0x02: Configures the R3 decimation rate as 6 for channel 1.
  11. Set address 0x23 = 0x02: Configures the R3 decimation rate as 6 for channel 2.
  12. Set address 0x24 = 0x02: Configures the R3 decimation rate as 6 for channel 3.
  13. Set address 0x27 = 0x08: Configures the DRDYB source to ECG channel 1 (or fastest channel).
  14. Set address 0x2F = 0x70: Enables ECG channel 1, ECG channel 2, and ECG channel 3 for loop read-back mode.
  15. Set address 0x00 = 0x01: Starts data conversion.

Follow the description in the Streaming section to read the data.

9.2.2.3 Application Curves

Figure 87 show measurement data collected by a single ADS1293 device connected to an ECG simulator configured to produce an ECG signals at a rate of 60 per minute and with an amplitude of 2 mV. The data was collected simultaneously by channels 1, 2 and 3 of the device during a period of 10 seconds.

Ex2_Lead_I_capture.png
Ex2_Lead_II_capture.png
Ex2_Lead_V_capture.pngFigure 87. Single ADS1293 Device With an ECG Simulator, CH1, CH2, and CH3: ECG Signals

9.2.3 8- or 12-Lead ECG Application

8_12lead_ecg_application_nas602.gifFigure 88. 8- or 12-Lead ECG Application

Figure 88 shows the ADS1293 master/slave setup for an 8-Lead to 12-Lead ECG system. The ADS1293 uses the Common-Mode Detector to measure the common-mode of the system by averaging the voltage of input pins IN1, IN2 and IN3, and uses this signal in the right-leg drive feedback circuit

(3) The ideal values of R1, R2 and C1 will vary per system / application; typical values for these components are: R1 = 100 kΩ, R2 = 1 MΩ and C1 = 1.5 nF.
. The output of the RLD amplifier is connected to the right-leg electrode to drive the common-mode of the system. The Wilson Central Terminal is generated by the ADS1293 and is used as a reference to measure the chest electrodes, V1-V6; TI strongly recommends shielding the external Wilson connections, which due to the high output impedance of the Wilson reference, is prone to pick up external interference. The master ADS1293 generates a synchronization pulse on the SYNCB pin (configured as an output). This drives the SYNCB pins (configured as inputs) of the two slave ADS1293. The master chip uses an external 4.096 MHz crystal oscillator connected between the XTAL1 and XTAL2 pins to create the clock source for the device and outputs this clock on the CLK pin.

9.2.3.1 Design Requirements

For this design example, use the parameters listed in Table 14 as the setup parameters.

Table 14. Design Parameters

DESIGN PARAMETER EXAMPLE VALUE
Number of electrodes 10
Lead I definition LA – RA
Lead II definition LL –RA
Lead V1 definition V1 – WCT
Lead V2 definition V2 – WCT
Lead V3 definition V3 – WCT
Lead V4 definition V4 – WCT
Lead V5 definition V5 – WCT
Lead V6 definition V6 – WCT
Bandwidth 175 Hz
Output data rate 853 sps
Analog supply voltage 5.0 V
Digital I/O supply voltage 3.3 V

9.2.3.2 Detailed Design Procedure

The next steps will configure the master device; it is assumed that the device registers contain their default power-up values.

  1. Set address 0x01 = 0x11: Connects channel 1’s INP to IN2 and INN to IN1.
  2. Set address 0x02 = 0x19: Connect channel 2’s INP to IN3 and INN to IN1.
  3. Set address 0x0A = 0x07: Enables the common-mode detector on input pins IN1, IN2 and IN3.
  4. Set address 0x0C = 0x04: Connects the output of the RLD amplifier internally to pin IN4.
  5. Set addresses 0x0D = 0x01, 0x0E = 0x02, 0x0F = 0x03: Connects the first buffer of the Wilson reference to the IN1 pin, the second buffer to the IN2 pin, and the third buffer to the IN3 pin.
  6. Set address 0x12 = 0x05: Uses external crystal, feeds the output of the internal oscillator module to the digital, and enables the CLK pin output driver
  7. Set address 0x14 = 0x24: Shuts down unused channel 3’s signal path.
  8. Set address 0x21 = 0x02: Configures the R2 decimation rate as 5 for all channels.
  9. Set address 0x22 = 0x02: Configures the R3 decimation rate as 6 for channel 1.
  10. Set address 0x23 = 0x02: Configures the R3 decimation rate as 6 for channel 2.
  11. Set address 0x27 = 0x08: Configures the data-ready source to channel 1 ECG (or fastest channel).
  12. Set address 0x28 = 0x08: Configures the synchronization source to channel 1 ECG (or slowest channel).
  13. Set address 0x2F = 0x30: Enables ECG channel 1 and ECG channel 2 for loop read-back mode.

    14. Next, configure the slave devices; it is assumed that the device registers contain their default power-up values. In this example, both devices will have the same configuration; therefore, they can potentially be configured in parallel by asserting the CSB signal of both chips.

  14. Set address 0x01 = 0x0C: Connects channel 1’s INP to IN1 and INN to IN4.
  15. Set address 0x02 = 0x14: Connects channel 2’s INP to IN2 and INN to IN4.
  16. Set address 0x03 = 0x1C: Connects channel 3’s INP to IN3 and INN to IN4.
  17. Set address 0x12 = 0x06: Uses external clock signal on the CLK pin and feeds it to the digital.
  18. Set address 0x21 = 0x02: Configures the R2 decimation rate as 5 for all channels.
  19. Set address 0x22 = 0x02: Configures the R3 decimation rate as 6 for channel 1.
  20. Set address 0x23 = 0x02: Configures the R3 decimation rate as 6 for channel 2.
  21. Set address 0x24 = 0x02: Configures the R3 decimation rate as 6 for channel 3.
  22. Set address 0x27 = 0x00: DRDYB pin not asserted by slave devices.
  23. Set address 0x28 = 0x40: Disables SYNCB driver and configures pin as input.
  24. Set address 0x2F = 0x70: Enables ECG channel 1, ECG channel 2, and ECG channel 3 for loop read-back mode.

    25. Finally, start the conversion. This should be written to all three chips.

  25. Set address 0x00 = 0x01: Starts data conversion (repeat this step for every device).

The three devices will run synchronously using the SYNCB signal. Follow the description in the Streaming section to read the data. The ADS1293 measures lead I, lead II and leads V1-V6. For a 12-lead application, the remaining 4 leads can be calculated as follows:

  • Lead III = Lead II – Lead I
  • aVR = – ( I + II ) / 2
  • aVL = I – II / 2
  • aVF = II – I / 2

9.2.3.3 Application Curves

Figure 89 show measurement data collected by 3 synchronized ADS1293 devices connected to an ECG simulator configured to produce an ECG signals at a rate of 60 per minute with an amplitude of 2 mV. The data was collected simultaneously by multiple channels from all 3 devices during a period of 10 seconds.

Ex3_Lead_I_capture.png
Ex3_Lead_II_capture.png
Ex3_Lead_V1_capture.png
Ex3_Lead_V2_capture.png
Ex3_Lead_V3_capture.png
Ex3_Lead_V4_capture.png
Ex3_Lead_V5_capture.png
Ex3_Lead_V6_capture.pngFigure 89. Three Synchornized ADS1293 Devices With an ECG Simulator: ECG Signals