SBAS459K January   2010  – August 2015 ADS1294 , ADS1294R , ADS1296 , ADS1296R , ADS1298 , ADS1298R

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison
  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 Timing Requirements: Serial Interface
    7. 7.7 Switching Characteristics: Serial Interface
    8. 7.8 Typical Characteristics
  8. 8 Parameter Measurement Information
    1. 8.1 Noise Measurements
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Analog Functionality
        1. 9.3.1.1 EMI Filter
        2. 9.3.1.2 Analog Input Structure
        3. 9.3.1.3 Input Multiplexer
          1. 9.3.1.3.1 Device Noise Measurements
          2. 9.3.1.3.2 Test Signals (TestP and TestN)
          3. 9.3.1.3.3 Auxiliary Differential Input (TESTP_PACE_OUT1, TESTN_PACE_OUT2)
          4. 9.3.1.3.4 Temperature Sensor (TempP, TempN)
          5. 9.3.1.3.5 Supply Measurements (MVDDP, MVDDN)
          6. 9.3.1.3.6 Lead-Off Excitation Signals (LoffP, LoffN)
          7. 9.3.1.3.7 Auxiliary Single-Ended Input
        4. 9.3.1.4 Analog Input
        5. 9.3.1.5 PGA Settings and Input Range
          1. 9.3.1.5.1 Input Common-Mode Range
          2. 9.3.1.5.2 Input Differential Dynamic Range
          3. 9.3.1.5.3 ADC Delta-Sigma Modulator
        6. 9.3.1.6 Reference
        7. 9.3.1.7 ECG-Specific Functions
          1. 9.3.1.7.1 Input Multiplexer (Rerouting The Right Leg Drive Signal)
          2. 9.3.1.7.2 Input Multiplexer (Measuring The Right Leg Drive Signal)
          3. 9.3.1.7.3 Wilson Central Terminal (WCT) and Chest Leads
            1. 9.3.1.7.3.1 Augmented Leads
            2. 9.3.1.7.3.2 Right Leg Drive with the WCT Point
          4. 9.3.1.7.4 Lead-Off Detection
            1. 9.3.1.7.4.1 DC Lead-Off
            2. 9.3.1.7.4.2 AC Lead-Off
          5. 9.3.1.7.5 RLD Lead-Off
          6. 9.3.1.7.6 Right Leg Drive (RLD) DC Bias Circuit
            1. 9.3.1.7.6.1 WCT as RLD
            2. 9.3.1.7.6.2 RLD Configuration with Multiple Devices
          7. 9.3.1.7.7 Pace Detect
            1. 9.3.1.7.7.1 Software Approach
            2. 9.3.1.7.7.2 External Hardware Approach
          8. 9.3.1.7.8 Respiration
            1. 9.3.1.7.8.1 External Respiration Circuitry (RESP_CTRL = 01b)
            2. 9.3.1.7.8.2 Internal Respiration Circuitry with Internal Clock (RESP_CTRL = 10b, ADS129xR Only)
            3. 9.3.1.7.8.3 Internal Respiration Circuitry With User-Generated Signals (RESP_CTRL = 11b, ADS129xR Only)
      2. 9.3.2 Digital Functionality
        1. 9.3.2.1 GPIO Pins (GPIO[4:1])
        2. 9.3.2.2 Power-Down Pin (PWDN)
        3. 9.3.2.3 Reset (RESET Pin and Reset Command)
        4. 9.3.2.4 Digital Decimation Filter
          1. 9.3.2.4.1 Sinc Filter Stage (sinx / x)
        5. 9.3.2.5 Clock
    4. 9.4 Device Functional Modes
      1. 9.4.1 Data Acquisition
        1. 9.4.1.1 Start Mode
          1. 9.4.1.1.1 Settling Time
        2. 9.4.1.2 Data Ready Pin (DRDY)
        3. 9.4.1.3 Data Retrieval
          1. 9.4.1.3.1 Status Word
          2. 9.4.1.3.2 Readback Length
          3. 9.4.1.3.3 Data Format
        4. 9.4.1.4 Single-Shot Mode
        5. 9.4.1.5 Continuous Conversion Mode
      2. 9.4.2 Multiple-Device Configuration
        1. 9.4.2.1 Cascade Configuration
        2. 9.4.2.2 Daisy-Chain Configuration
    5. 9.5 Programming
      1. 9.5.1 SPI Interface
        1. 9.5.1.1 Chip Select Pin (CS)
        2. 9.5.1.2 Serial Clock (SCLK)
          1. 9.5.1.2.1 SCLK Clocking Methods
        3. 9.5.1.3 Data Input Pin (DIN)
        4. 9.5.1.4 Data Output Pin (DOUT)
      2. 9.5.2 SPI Command Definitions
        1. 9.5.2.1  WAKEUP: Exit Standby Mode
        2. 9.5.2.2  STANDBY: Enter Standby Mode
        3. 9.5.2.3  RESET: Reset Registers to Default Values
        4. 9.5.2.4  START: Start Conversions
        5. 9.5.2.5  STOP: Stop Conversions
        6. 9.5.2.6  RDATAC: Read Data Continuous
        7. 9.5.2.7  SDATAC: Stop Read Data Continuous
        8. 9.5.2.8  RDATA: Read Data
        9. 9.5.2.9  Sending Multibyte Commands
        10. 9.5.2.10 RREG: Read From Register
        11. 9.5.2.11 WREG: Write to Register
    6. 9.6 Register Maps
      1. 9.6.1 Register Descriptions
        1. 9.6.1.1  ID: ID Control Register (address = 00h) (reset = xxh)
        2. 9.6.1.2  CONFIG1: Configuration Register 1 (address = 01h) (reset = 06h)
        3. 9.6.1.3  CONFIG2: Configuration Register 2 (address = 02h) (reset = 40h)
        4. 9.6.1.4  CONFIG3: Configuration Register 3 (address = 03h) (reset = 40h)
        5. 9.6.1.5  LOFF: Lead-Off Control Register (address = 04h) (reset = 00h)
        6. 9.6.1.6  CHnSET: Individual Channel Settings (n = 1 to 8) (address = 05h to 0Ch) (reset = 00h)
        7. 9.6.1.7  RLD_SENSP: RLD Positive Signal Derivation Register (address = 0Dh) (reset = 00h)
        8. 9.6.1.8  RLD_SENSN: RLD Negative Signal Derivation Register (address = 0Eh) (reset = 00h)
        9. 9.6.1.9  LOFF_SENSP: Positive Signal Lead-Off Detection Register (address = 0Fh) (reset = 00h)
        10. 9.6.1.10 LOFF_SENSN: Negative Signal Lead-Off Detection Register (address = 10h) (reset = 00h)
        11. 9.6.1.11 LOFF_FLIP: Lead-Off Flip Register (address = 11h) (reset = 00h)
        12. 9.6.1.12 LOFF_STATP: Lead-Off Positive Signal Status Register (address = 12h) (reset = 00h)
        13. 9.6.1.13 LOFF_STATN: Lead-Off Negative Signal Status Register (address = 13h) (reset = 00h)
        14. 9.6.1.14 GPIO: General-Purpose I/O Register (address = 14h) (reset = 0Fh)
        15. 9.6.1.15 PACE: Pace Detect Register (address = 15h) (reset = 00h)
        16. 9.6.1.16 RESP: Respiration Control Register (address = 16h) (reset = 00h)
        17. 9.6.1.17 CONFIG4: Configuration Register 4 (address = 17h) (reset = 00h)
        18. 9.6.1.18 WCT1: Wilson Central Terminal and Augmented Lead Control Register (address = 18h) (reset = 00h)
        19. 9.6.1.19 WCT2: Wilson Central Terminal Control Register (address = 18h) (reset = 00h)
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Setting the Device for Basic Data Capture
        1. 10.1.1.1 Lead-Off
        2. 10.1.1.2 Right Leg Drive
        3. 10.1.1.3 Pace Detection
      2. 10.1.2 Establishing the Input Common-Mode
      3. 10.1.3 Antialiasing
    2. 10.2 Typical Applications
      1. 10.2.1 ADS129xR Respiration Measurement Using Internal Modulation Circuitry
        1. 10.2.1.1 Design Requirements
        2. 10.2.1.2 Detailed Design Procedure
        3. 10.2.1.3 Application Curve
      2. 10.2.2 Software-Based Artificial Pacemaker Detection Using the PACEOUT Pins on the ADS129x
        1. 10.2.2.1 Design Requirements
        2. 10.2.2.2 Detailed Design Procedure
        3. 10.2.2.3 Application Curve
  11. 11Power Supply Recommendations
    1. 11.1 Power-Up Sequencing
    2. 11.2 Connecting to Unipolar (3 V or 1.8 V) Supplies
    3. 11.3 Connecting to Bipolar (±1.5 V or ±1.8 V) Supplies
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Related Links
    2. 13.2 Community Resources
    3. 13.3 Trademarks
    4. 13.4 Electrostatic Discharge Caution
    5. 13.5 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

11 Power Supply Recommendations

The ADS129x have three power supplies: AVDD, AVDD1, and DVDD. For best performance, both AVDD and AVDD1 must be as quiet as possible. AVDD1 provides the supply to the charge pump block and has transients at fCLK. Therefore, star connect AVDD1 and AVSS1 to AVDD and AVSS. It is important to eliminate noise from AVDD and AVDD1 that is nonsynchronous with ADS129x operation. Bypass each ADS129x supply with 1-μF and 0.1-μF solid ceramic capacitors. For best performance, place the digital circuits (DSP, microcontrollers, FPGAs, and so forth) in the system so that the return currents on those devices do not cross the analog return path of the ADS129x. Power the ADS129x from unipolar or bipolar supplies.

Use surface-mount, low-cost, low-profile, multilayer ceramic-type capacitors for decoupling. In most cases, the VCAP1 capacitor is also a multilayer ceramic; however, in systems where the board is subjected to high- or low-frequency vibration, install a nonferroelectric capacitor, such as a tantalum or class 1 capacitor (C0G or NPO). EIA class 2 and class 3 dielectrics such as (X7R, X5R, X8R, and so forth) are ferroelectric. The piezoelectric property of these capacitors can appear as electrical noise coming from the capacitor. When using internal reference, noise on the VCAP1 node results in performance degradation.

11.1 Power-Up Sequencing

Before device power up, all digital and analog inputs must be low. At the time of power up, keep all of these signals low until the power supplies have stabilized, as shown in Figure 105.

Allow time for the supply voltages to reach their final value, and then begin supplying the master clock signal to the CLK pin. Wait for time tPOR, then transmit a reset pulse using either the RESET pin or RESET command to initialize the digital portion of the chip. Issue the reset after tPOR or after the VCAP1 voltage is greater than 1.1 V, whichever time is longer. Note that:

  • tPOR is described in Table 38.
  • The VCAP1 pin charge time is set by the RC time constant; see Figure 31.

After releasing the RESET pin, program the configuration registers; see the CONFIG1: Configuration Register 1 (address = 01h) (reset = 06h) section for details. The power-up sequence timing is shown in Table 38.

ADS1294 ADS1294R ADS1296 ADS1296R ADS1298 ADS1298R POR_timingdiagram_sbas459.gif
1. Timing to reset pulse is tPOR or after tBG, whichever is longer.
2. When using an external clock, tPOR timing does not start until CLK is valid.
Figure 105. Power-Up Timing Diagram

Table 38. Timing Requirements for Figure 105

MIN MAX UNIT
tPOR Wait after power up until reset 218 tCLK
tRST Reset low duration 2 tCLK

11.2 Connecting to Unipolar (3 V or 1.8 V) Supplies

Figure 106 illustrates the ADS129x connected to a unipolar supply. In this example, analog supply (AVDD) is referenced to analog ground (AVSS) and digital supplies (DVDD) are referenced to digital ground (DGND).

ADS1294 ADS1294R ADS1296 ADS1296R ADS1298 ADS1298R ai_single_supply_bas506.gif
NOTE: Place the capacitors for supply, reference, WCT, and VCAP1 to VCAP4 as close to the package as possible.
Figure 106. Single-Supply Operation

11.3 Connecting to Bipolar (±1.5 V or ±1.8 V) Supplies

Figure 107 illustrates the ADS129x connected to a bipolar supply. In this example, the analog supplies connect to the device analog supply (AVDD). This supply is referenced to the device analog return (AVSS), and the digital supply (DVDD) is referenced to the device digital ground return (DGND).

ADS1294 ADS1294R ADS1296 ADS1296R ADS1298 ADS1298R ai_bipolar_supply_bas506.gif
NOTE: Place the capacitors for supply, reference, WCT, and VCAP1 to VCAP4 as close to the package as possible.
Figure 107. Bipolar Supply Operation