SBASAM0B March   2024  – November 2024 ADS127L18

PRODMIX  

  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
    7. 5.7 Switching Characteristics
    8. 5.8 Timing Diagrams
    9. 5.9 Typical Characteristics
  7. 6 Parameter Measurement Information
    1. 6.1  Offset Error Measurement
    2. 6.2  Offset Drift Measurement
    3. 6.3  Gain Error Measurement
    4. 6.4  Gain Drift Measurement
    5. 6.5  NMRR Measurement
    6. 6.6  CMRR Measurement
    7. 6.7  PSRR Measurement
    8. 6.8  SNR Measurement
    9. 6.9  INL Error Measurement
    10. 6.10 THD Measurement
    11. 6.11 IMD Measurement
    12. 6.12 SFDR Measurement
    13. 6.13 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 Inputs (AINP, AINN)
        1. 7.3.1.1 Input Range
      2. 7.3.2 Reference Voltage (REFP, REFN)
        1. 7.3.2.1 Reference Voltage Range
      3. 7.3.3 Clock Operation
        1. 7.3.3.1 Clock Dividers
        2. 7.3.3.2 Internal Oscillator
        3. 7.3.3.3 External Clock
      4. 7.3.4 Power-On Reset (POR)
      5. 7.3.5 VCM Output Voltage
      6. 7.3.6 GPIO
      7. 7.3.7 Modulator
      8. 7.3.8 Digital Filter
        1. 7.3.8.1 Wideband Filter
        2. 7.3.8.2 Low-Latency Filter (Sinc)
          1. 7.3.8.2.1 Sinc4 Filter
          2. 7.3.8.2.2 Sinc4 + Sinc1 Cascade Filter
          3. 7.3.8.2.3 Sinc3 Filter
          4. 7.3.8.2.4 Sinc3 + Sinc1 Filter
    4. 7.4 Device Functional Modes
      1. 7.4.1  Reset
        1. 7.4.1.1 RESET Pin
        2. 7.4.1.2 Reset by SPI Register
        3. 7.4.1.3 Reset by SPI Input Pattern
      2. 7.4.2  Idle and Standby Modes
      3. 7.4.3  Power-Down
      4. 7.4.4  Speed Modes
      5. 7.4.5  Synchronization
        1. 7.4.5.1 Synchronized Control Mode
        2. 7.4.5.2 Start/Stop Control Mode
      6. 7.4.6  Conversion-Start Delay Time
      7. 7.4.7  Calibration
        1. 7.4.7.1 Offset Calibration Registers
        2. 7.4.7.2 Gain Calibration Registers
        3. 7.4.7.3 Calibration Procedure
      8. 7.4.8  Data Averaging
      9. 7.4.9  Diagnostics
        1. 7.4.9.1 ERROR Pin and ERR_FLAG Bit
        2. 7.4.9.2 SPI CRC
        3. 7.4.9.3 Register Map CRC
        4. 7.4.9.4 ADC Error
        5. 7.4.9.5 SPI Address Range
        6. 7.4.9.6 SCLK Counter
        7. 7.4.9.7 Clock Counter
        8. 7.4.9.8 Frame-Sync CRC
        9. 7.4.9.9 Self Test
      10. 7.4.10 Frame-Sync Data Port
        1. 7.4.10.1  Data Packet
        2. 7.4.10.2  Data Format
        3. 7.4.10.3  STATUS_DP Header Byte
        4. 7.4.10.4  FSYNC Pin
        5. 7.4.10.5  DCLK Pin
        6. 7.4.10.6  DOUTx Pins
        7. 7.4.10.7  DINx Pins
        8. 7.4.10.8  Time Division Multiplexing
        9. 7.4.10.9  Daisy Chain
        10. 7.4.10.10 DOUTx Timing
    5. 7.5 Programming
      1. 7.5.1 Hardware Programming
      2. 7.5.2 SPI Programming
        1. 7.5.2.1 Chip Select (CS)
        2. 7.5.2.2 Serial Clock (SCLK)
        3. 7.5.2.3 Serial Data Input (SDI)
        4. 7.5.2.4 Serial Data Output (SDO)
      3. 7.5.3 SPI Frame
      4. 7.5.4 Commands
        1. 7.5.4.1 Write Register Command
        2. 7.5.4.2 Read Register Command
      5. 7.5.5 SPI Daisy-Chain
  9. 8 Register Map
  10. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Input Driver
      2. 9.1.2 Antialias Filter
      3. 9.1.3 Reference Voltage
    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 AVDD1 and AVSS
      2. 9.3.2 AVDD2
      3. 9.3.3 IOVDD
      4. 9.3.4 CAPA and CAPD
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Related Documentation
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

9.3 Power Supply Recommendations

The ADCs have three analog power supplies and one digital power supply. Power-supply voltages AVDD1 and AVSS configure the channels for unipolar or bipolar signal types. Example configurations are AVDD1 = 5V and AVSS = DGND for unipolar signals, and AVDD1 = 2.5V and AVSS = –2.5V for bipolar signals. The AVDD2 power-supply voltage is with respect to AVSS and the IOVDD power-supply voltage is with respect to DGND. The specified range of the power supplies are listed in the Recommended Operating Conditions.

Table 9-2 shows power-supply configuration options. The power-supply voltage values shown are nominal.

Table 9-2 Power-Supply Configurations (Nominal)
SPEED MODE CONFIGURATION AVDD1 – DGND AVSS – DGND AVDD2 – DGND IOVDD – DGND
Max speed Unipolar 5V 0V 1.8V to 5V 1.8V
Bipolar 2.5V –2.5V 0V to 2.5V 1.8V
High speed Unipolar 5V 0V 1.8V to 5V 1.8V
Bipolar 2.5V –2.5V 0V to 2.5V 1.8V
Mid speed Unipolar 3.3V to 5V 0V 1.8V to 5V 1.8V
Bipolar 1.65V to 2.5V –1.65V to –2.5V 0.15V to 2.5V 1.8V
Low speed Unipolar 3V to 5V 0V 1.8V to 5V 1.8V
Bipolar 1.5V to 2.5V –1.5V to –2.5V 0.3V to 2.5V 1.8V

The power supplies do not require special sequencing and are able to be powered up in any order and are tolerant to slow or fast ramp rates. However, make sure no analog or digital input exceeds the respective AVDD1 and AVSS (analog) or IOVDD (digital) power-supply voltages. An internal reset is performed after the IOVDD power-supply voltage is applied.

Table 9-3 shows the recommended bypass capacitors for the devices. All capacitors are minimum 6.3V, X7R ceramic dielectric. In addition to using a single ground plane for DGND, best performance is achieved with power planes for IOVDD, AVDD1, AVDD2, and AVSS. If AVSS = 0V for unipolar supply operation, use one ground plane for AVSS and DGND. If AVSS = -2.5V for bipolar supply operation, bypass AVSS and AVDD1 to the DGND plane.

For both the ADS127L14 and the ADS127L18, AVSS pin numbers 45 and 51 do not require bypass capacitors. In addition, the ADS127L14 AVSS pin numbers 29 through 36 do not require bypass capacitors. Tie these pins to the AVSS plane.

Table 9-3 Bypass Capacitors
POSITIVE PINS NEGATIVE PINS CAPACITOR (X7R)
IOVDD (pins 18, 19 tied together) DGND (pin17) 2.2uF
CAPD (pin 20) DGND (pin 21) 2.2uF
AVDD1 (pins 23, 24 tied together) AVSS (pin 22) 2.2uF
AVDD2 (pin 25) AVSS (pin 22) 2.2uF
CAPA (pins 26, 27 tied together) AVSS (pin 28) 10uF
REFP (pins 49, 50 tied together) REFN (pins 47, 48 tied together) 2.2µF (REFP buffer on), 10uF (REFP buffer off)
REFN (pins 47, 48 tied together) AVSS (pins 45, 51 tied together) 2.2µF (only required if REFN is not tied to ground)