SBAS946C April   2021  – September 2022 ADS127L11

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  ESD Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information
    5. 6.5  Electrical Characteristics
    6. 6.6  Timing Requirements (1.65 V ≤ IOVDD ≤ 2 V)
    7. 6.7  Switching Characteristics (1.65 V ≤ IOVDD ≤ 2 V)
    8. 6.8  Timing Requirements (2 V < IOVDD ≤ 5.5 V)
    9. 6.9  Switching Characteristics (2 V < IOVDD ≤ 5.5 V)
    10. 6.10 Timing Diagrams
    11. 6.11 Typical Characteristics
  7. 7 Parameter Measurement Information
    1. 7.1  Offset Error Measurement
    2. 7.2  Offset Drift Measurement
    3. 7.3  Gain Error Measurement
    4. 7.4  Gain Drift Measurement
    5. 7.5  NMRR Measurement
    6. 7.6  CMRR Measurement
    7. 7.7  PSRR Measurement
    8. 7.8  SNR Measurement
    9. 7.9  INL Error Measurement
    10. 7.10 THD Measurement
    11. 7.11 SFDR Measurement
    12. 7.12 Noise Performance
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Analog Input (AINP, AINN)
        1. 8.3.1.1 Input Range
      2. 8.3.2 Reference Voltage (REFP, REFN)
        1. 8.3.2.1 Reference Voltage Range
      3. 8.3.3 Clock Operation
        1. 8.3.3.1 Internal Oscillator
        2. 8.3.3.2 External Clock
      4. 8.3.4 Modulator
      5. 8.3.5 Digital Filter
        1. 8.3.5.1 Wideband Filter
        2. 8.3.5.2 Low-Latency Filter (Sinc)
          1. 8.3.5.2.1 Sinc4 Filter
          2. 8.3.5.2.2 Sinc4 + Sinc1 Filter
          3. 8.3.5.2.3 Sinc3 Filter
          4. 8.3.5.2.4 Sinc3 + Sinc1 Filter
      6. 8.3.6 Power Supplies
        1. 8.3.6.1 AVDD1 and AVSS
        2. 8.3.6.2 AVDD2
        3. 8.3.6.3 IOVDD
        4. 8.3.6.4 Power-On Reset (POR)
        5. 8.3.6.5 CAPA and CAPD
      7. 8.3.7 VCM Output Voltage
    4. 8.4 Device Functional Modes
      1. 8.4.1 Power-Scalable Speed Modes
      2. 8.4.2 Idle Mode
      3. 8.4.3 Standby Mode
      4. 8.4.4 Power-Down Mode
      5. 8.4.5 Reset
        1. 8.4.5.1 RESET Pin
        2. 8.4.5.2 Reset by SPI Register Write
        3. 8.4.5.3 Reset by SPI Input Pattern
      6. 8.4.6 Synchronization
        1. 8.4.6.1 Synchronized Control Mode
        2. 8.4.6.2 Start/Stop Control Mode
        3. 8.4.6.3 One-Shot Control Mode
      7. 8.4.7 Conversion-Start Delay Time
      8. 8.4.8 Calibration
        1. 8.4.8.1 OFFSET2, OFFSET1, OFFSET0 Calibration Registers (Addresses 9h, Ah, Bh)
        2. 8.4.8.2 GAIN2, GAIN1, GAIN0 Calibration Registers (Addresses 0Ch, 0Dh, 0Eh)
        3. 8.4.8.3 Calibration Procedure
    5. 8.5 Programming
      1. 8.5.1 Serial Interface (SPI)
        1. 8.5.1.1 Chip Select (CS)
        2. 8.5.1.2 Serial Clock (SCLK)
        3. 8.5.1.3 Serial Data Input (SDI)
        4. 8.5.1.4 Serial Data Output/Data Ready (SDO/DRDY)
      2. 8.5.2 SPI Frame
      3. 8.5.3 SPI CRC
      4. 8.5.4 Register Map CRC
      5. 8.5.5 Full-Duplex Operation
      6. 8.5.6 Device Commands
        1. 8.5.6.1 No-Operation
        2. 8.5.6.2 Read Register Command
        3. 8.5.6.3 Write Register Command
      7. 8.5.7 Read Conversion Data
        1. 8.5.7.1 Conversion Data
        2. 8.5.7.2 Data Ready
          1. 8.5.7.2.1 DRDY
          2. 8.5.7.2.2 SDO/DRDY
          3. 8.5.7.2.3 DRDY Bit
          4. 8.5.7.2.4 Clock Counting
        3. 8.5.7.3 STATUS Header
      8. 8.5.8 Daisy-Chain Operation
      9. 8.5.9 3-Wire SPI Mode
        1. 8.5.9.1 3-Wire SPI Mode Frame Reset
    6. 8.6 Registers
      1. 8.6.1  DEV_ID Register (Address = 0h) [reset = 00h]
      2. 8.6.2  REV_ID Register (Address = 1h) [reset = xxh]
      3. 8.6.3  STATUS Register (Address = 2h) [reset = x1100xxxb]
      4. 8.6.4  CONTROL Register (Address = 3h) [reset = 00h]
      5. 8.6.5  MUX Register (Address = 4h) [reset = 00h]
      6. 8.6.6  CONFIG1 Register (Address = 5h) [reset = 00h]
      7. 8.6.7  CONFIG2 Register (Address = 6h) [reset = 00h]
      8. 8.6.8  CONFIG3 Register (Address = 7h) [reset = 00h]
      9. 8.6.9  CONFIG4 Register (Address = 8h) [reset = 00h]
      10. 8.6.10 OFFSET2, OFFSET1, OFFSET0 Registers (Addresses = 9h, Ah, Bh) [reset = 00h, 00h, 00h]
      11. 8.6.11 GAIN2, GAIN1, GAIN0 Registers (Addresses = Ch, Dh, Eh) [reset = 40h, 00h, 00h]
      12. 8.6.12 CRC Register (Address = Fh) [reset = 00h]
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 SPI Operation
      2. 9.1.2 Input Driver
      3. 9.1.3 Antialias Filter
      4. 9.1.4 Reference Voltage
      5. 9.1.5 Simultaneous-Sampling Systems
    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
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  10. 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
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

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

7.12 Noise Performance

The ADC provides two operational speed modes (high speed and low speed) that allow trade-offs between ADC resolution, power consumption, and signal bandwidth. Low-speed mode operates the modulator at 1/8th speed for decreased device power consumption and, as a result, the output data rates are reduced by 1/8th. The programmable oversampling ratio (OSR) determines the output data rate and associated signal bandwidth, and therefore also determines the total noise performance. Increasing the OSR lowers the signal bandwidth and total noise by averaging more samples from the modulator to yield one conversion result.

The wideband filter provides data rates up to 400 kSPS in high-speed mode and 50 kSPS in low-speed mode. The low-latency sinc4 filter provides data rates up to 1.067 MSPS in high-speed mode and up to 133 kSPS in low-speed mode. The low-latency filter provides the options of sinc4, sinc4 + sinc1, sinc3, and sinc3 + sinc1 configurations.

Table 7-1 through Table 7-5 summarize the noise performance and signal bandwidth of the various filter modes. Noise performance is shown with 1x input range and a 4.096-V reference voltage. In comparison, decreasing the reference voltage to 2.5 V decreases dynamic range by 4 dB (typical). Operation in 2x input range and a 2.5-V reference voltage decreases dynamic range by 3 dB (typical) compared to 1x input range and 4.096-V reference voltage operation.

The noise data are the result of the standard deviation (rms) of the conversion data with inputs shorted and biased to the mid-supply voltage and are representative of typical performance at TA = 25°C. A minimum of 1,000 or 10 seconds of consecutive conversions (whichever occurs first) are used to measure RMS noise (en). Because of the statistical nature of noise, repeated noise measurements can yield higher or lower noise results.

Equation 12 converts RMS noise to dynamic range (dB) and Equation 13 converts RMS noise to effective resolution (bits).

Equation 12. Dynamic Range (dB) = 20 · log[FSR / (2 · √2 · en)]
Equation 13. Effective Resolution (bits) = log2(FSR / en)

where:

  • FSR = 2 · VREF (1x input range)
  • FSR = 4 · VREF (2x input range)
  • en = Noise voltage (RMS)

When evaluating ADC noise performance, consider the effect of external buffer and amplifier noise to the total noise performance. The noise performance of the ADC can be evaluated in isolation by selecting the input short test connection of the input multiplexer.

Table 7-1 Wideband Filter Performance (VREF = 4.096 V, 1x Input Range)
OSR DATA RATE
(kSPS)		 –0.1-dB FREQUENCY
(kHz)		 NOISE (en)
(µVRMS)		 DYNAMIC RANGE
(dB)		 EFFECTIVE RESOLUTION
(Bits)
HIGH-SPEED MODE (fCLK = 25.6 MHz)
32 400 165.000 10.6 108.7 19.5
64 200 82.500 7.47 111.8 20.1
128 100 41.250 5.20 114.9 20.6
256 50 20.625 3.66 118.0 21.1
512 25 10.312 2.58 121.0 21.6
1024 12.5 5.156 1.83 124.0 22.1
2048 6.25 2.578 1.29 127.0 22.6
4096 3.125 1.289 0.92 130.0 23.1
LOW-SPEED MODE (fCLK = 3.2 MHz)
32 50 20.625 10.6 108.7 19.5
64 25 10.312 7.47 111.8 20.1
128 12.5 5.156 5.20 114.9 20.6
256 6.25 2.578 3.66 118.0 21.1
512 3.125 1.289 2.58 121.0 21.6
1024 1.5625 0.645 1.83 124.0 22.1
2048 0.78125 0.322 1.29 127.0 22.6
4096 0.390625 0.161 0.92 130.0 23.1
Table 7-2 Sinc4 Filter Performance (VREF = 4.096 V, 1x Input Range)
OSR DATA RATE
(kSPS)		 –3-dB FREQUENCY
(kHz)		 NOISE (en)
(µVRMS)		 DYNAMIC RANGE
(dB)		 EFFECTIVE RESOLUTION
(Bits)
HIGH-SPEED MODE (fCLK = 25.6 MHz)
12 1066.666 242.666 76.3 91.6 16.7
16 800 182.000 27.3 100.5 18.2
24 533.333 121.333 10.4 108.9 19.6
32 400 91.000 7.96 111.2 20.0
64 200 45.500 5.57 114.3 20.5
128 100 22.750 3.90 117.4 21.0
256 50 11.375 2.80 120.3 21.5
512 25 5.687 1.98 123.3 22.0
1024 12.5 2.844 1.40 126.3 22.5
2048 6.25 1.422 0.99 129.3 23.0
4096 3.125 0.711 0.70 132.3 23.5
LOW-SPEED MODE (fCLK = 3.2 MHz)
12 133.333 30.333 76.3 91.6 16.7
16 100 22.750 27.3 100.5 18.2
24 66.666 15.166 10.4 108.9 19.6
32 50 11.375 7.96 111.2 20.0
64 25 5.687 5.57 114.3 20.5
128 12.5 2.844 3.90 117.4 21.0
256 6.25 1.422 2.80 120.3 21.5
512 3.125 0.711 1.98 123.3 22.0
1024 1.5625 0.355 1.40 126.3 22.5
2048 0.78125 0.177 0.99 129.3 23.0
4096 0.390625 0.089 0.70 132.3 23.5
Table 7-3 Sinc4 + Sinc1 Filter Performance (VREF = 4.096 V, 1x Input Range)
SINC4 OSR SINC1 OSR DATA RATE
(kSPS)		 –3-dB FREQUENCY
(kHz)		 NOISE (en)
(µVRMS)		 DYNAMIC RANGE
(dB)		 EFFECTIVE RESOLUTION
(Bits)
HIGH-SPEED MODE (fCLK = 25.6 MHz)
32 2 200 68.35 5.63 114.2 20.5
32 4 100 40.97 3.98 117.2 21.0
32 10 40 17.47 2.81 120.3 21.5
32 20 20 8.814 1.99 123.3 22.0
32 40 10 4.420 1.41 126.3 22.5
32 100 4 1.770 0.99 129.3 23.0
32 200 2 0.885 0.70 132.3 23.5
32 400 1 0.442 0.52 134.9 23.9
32 1000 0.4 0.177 0.39 137.4 24.3
LOW-SPEED MODE (fCLK = 3.2 MHz)
32 2 25 8.544 5.63 114.2 20.5
32 4 12.5 5.121 3.98 117.2 21.0
32 10 5 2.184 2.81 120.3 21.5
32 20 2.5 1.102 1.99 123.3 22.0
32 40 1.25 0.552 1.41 126.3 22.5
32 100 0.5 0.221 0.99 129.3 23.0
32 200 0.25 0.111 0.70 132.3 23.5
32 400 0.125 0.055 0.52 134.9 23.9
32 1000 0.05 0.022 0.39 137.4 24.3
Table 7-4 Sinc3 Filter Performance (VREF = 4.096 V, 1x Input Range)
OSR DATA RATE
(SPS)		 –3-dB FREQUENCY
(Hz)		 NOISE (en)
(µVRMS) (1)		 DYNAMIC RANGE
(dB)		 EFFECTIVE RESOLUTION
(Bits)
HIGH-SPEED MODE (fCLK = 25.6 MHz)
26667 480 126 0.29 140.0 24.7
32000 400 105 0.27 140.6 24.8
LOW-SPEED MODE (fCLK = 3.2 MHz)
26667 60 16 0.29 140.0 24.7
32000 50 13 0.27 140.6 24.8
(1) The noise measurement may vary resulting from the effects of 24-bit quantization levels: 4.096 V / 223 = 0.488 μV / code.
Table 7-5 Sinc3 + Sinc1 Filter Performance (VREF = 4.096 V, 1x Input Range)
SINC3 OSR SINC1 OSR DATA RATE
(SPS)		 –3-dB FREQUENCY
(Hz)		 NOISE (en)
(µVRMS) (1)		 DYNAMIC RANGE
(dB)		 EFFECTIVE RESOLUTION
(Bits)
HIGH-SPEED MODE (fCLK = 25.6 MHz)
32000 3 133.3 54 0.19 143.7 25.3
32000 5 80 34 0.15 145.7 25.7
LOW-SPEED MODE (fCLK = 3.2 MHz)
32000 3 16.6 6.7 0.19 143.7 25.3
32000 5 10 4.3 0.15 145.7 25.7
(1) The noise measurement may vary resulting from the effects of 24-bit quantization levels: 4.096 V / 223 = 0.488 μV / code.