SBASB89 May   2025 ADS117L14 , ADS117L18

PRODUCTION DATA  

  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 Diagnostics
        1. 7.4.8.1 ERROR Pin and ERR_FLAG Bit
        2. 7.4.8.2 SPI CRC
        3. 7.4.8.3 Register Map CRC
        4. 7.4.8.4 ADC Error
        5. 7.4.8.5 SPI Address Range
        6. 7.4.8.6 SCLK Counter
        7. 7.4.8.7 Clock Counter
        8. 7.4.8.8 Frame-Sync CRC
        9. 7.4.8.9 Self Test
      9. 7.4.9 Frame-Sync Data Port
        1. 7.4.9.1  Data Packet
        2. 7.4.9.2  Data Format
        3. 7.4.9.3  STATUS_DP Header Byte
        4. 7.4.9.4  FSYNC Pin
        5. 7.4.9.5  DCLK Pin
        6. 7.4.9.6  DOUTx Pins
        7. 7.4.9.7  DINx Pins
        8. 7.4.9.8  Time Division Multiplexing
        9. 7.4.9.9  Daisy Chain
        10. 7.4.9.10 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 Anti-alias 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

Package Options

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

7.4.9.5 DCLK Pin

The DCLK pin is the frame-sync port bit-clock output signal that shifts out conversion data from the DOUTx pins. Data are updated on the falling DCLK edge and are read on the rising DCLK edge.

The DCLK frequency is derived from the clock input signal by a programmable divider. See the Clock Operation section for the details of the CLK and DCLK dividers. The DCLK signal frequency must be sufficient to transmit the data in one conversion period, otherwise data are lost. Equation 20 shows how to calculate the minimum DCLK frequency for the eight-channel ADS117L18.

Equation 20. fDCLK ≥ fDATA · TDM ratio · Data Packet Size

where:

  • fDATA = Data rate (Hz).
  • TDM ratio = 1: eight data lanes, 2: four data lanes, 4: two data lanes, 8: one data lane.
  • Data packet = Number of bits in a channel data packet (16, 24 or 32 bits).

As an example of the eight-channel ADS117L18 operating with fDATA = 200kSPS, TDM ratio = 2 (four data lanes), and 32-bit data packet, the minimum DCLK frequency = 200kHz · 2 · 32 = 12.8MHz. DCLK can be higher than the required minimum in which case the extra bits occurring after the data packet bits are ignored. For the four-channel ADS117L14, divide the TDM ratio in the fDCLK equation (pertaining to the number of data lanes) by two. When operating devices in daisy-chain mode, multiply the TDM ratio in the fDCLK equation by the number of devices in the chain.

Table 7-19 shows additional examples of CLK and DCLK frequencies for the ADS117L18. Use the DCLK and CLK dividers to provide the required ADC and DCLK clock frequencies based on the speed mode, data rate, TDM ratio and packet size.

Table 7-14 DCLK Frequency Examples for Eight-Channel ADS117L18
SPEED MODEDATA RATE
(kSPS)		TDM RATIOPACKET SIZEDCLK MIN
(MHz)		CLKIN INPUT
(MHZ)		CLK DIVIDER(1)ADC CLOCK
(MHz)		DCLK DIVIDER(1)DCLK ACTUAL (MHz)
Max1365.322465.53665.536232.768165.536
Max51212412.28832.768132.768216.384
Max51242449.15265.536232.768165.536
High40042438.451.2225.6151.2
Mid20043225.625.6212.8125.6
Mid 200 1 32 6.4 12.8 1 12.8 1 12.8
Low5083212.812.843.2112.8
(1) Daisy chain operation requires that the CLK and DCLK dividers are programmed to the divide by 1 option.