SBAS580D May   2013  – March 2018 ADS7250 , ADS7850 , ADS8350

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Functional Block Diagram
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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: All Devices
    6. 6.6  Electrical Characteristics: ADS7250
    7. 6.7  Electrical Characteristics: ADS7850
    8. 6.8  Electrical Characteristics: ADS8350
    9. 6.9  Timing Requirements
    10. 6.10 Switching Characteristics
    11. 6.11 Typical Characteristics: ADS7250
    12. 6.12 Typical Characteristics: ADS7850
    13. 6.13 Typical Characteristics: ADS8350
    14. 6.14 Typical Characteristics: All Devices
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Reference
      2. 7.3.2 Analog Input
        1. 7.3.2.1 Analog Input Full-Scale Range
      3. 7.3.3 ADC Transfer Function
    4. 7.4 Device Functional Modes
      1. 7.4.1 Serial Interface
      2. 7.4.2 Short-Cycling, Frame Abort, and Reconversion Feature
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 DAQ Circuit: Maximum SINAD for a 10-kHz Input Signal at 750-kSPS Throughput
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 ADC Reference Driver
          2. 8.2.1.2.2 ADC Input Driver
            1. 8.2.1.2.2.1 Input Amplifier Selection
            2. 8.2.1.2.2.2 Antialiasing Filter
        3. 8.2.1.3 Application Curve
      2. 8.2.2 DAQ Circuit: Maximum SINAD for a 100-kHz Input Signal at 750-kSPS Throughput
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1 ADC Reference Driver
          2. 8.2.2.2.2 ADC Input Driver
        3. 8.2.2.3 Application Curve
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Related Links
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.3 ADC Transfer Function

The device output is in binary twos complement format. Device resolution is calculated by Equation 6:

Equation 6. 1 LSB = (FSR_ADC_x) / (2N)

where

  • FSR_ADC_x = 2 x VREFIN_x and
  • N is the resolution of the ADC : N = 16 for the ADS8350, N = 14 for the ADS7850, and N = 12 for the ADS7250

Table 1 shows the different input voltages and the corresponding device output codes.

Table 1. Transfer Characteristics

INPUT VOLTAGE
(AINM_x)		 INPUT VOLTAGE
(AINP_x)		 PSEUDO-DIFFERENTIAL INPUT TO ADC
(AINP_x - AINM_x)		 OUTPUT CODE (HEX)
CODE ADS7250 ADS7850 ADS8350
VREFIN_x 0 –VREFIN_x NFSR NFSC 800 2000 8000
1 LSB – VREFIN_x + 1 LSB NFSR + 1 LSB NFSC + 1 801 2001 8001
VREFIN_x – 1 LSB –1 LSB –1 LSB MC FFF 3FFF FFFF
VREFIN_x 0 0 PLC 000 0000 0000
2 × VREFIN_x – 1 LSB VREFIN_x – 1 LSB PFSR – 1 LSB PFSC 7FF 1FFF 7FFF

Figure 51 shows the ideal transfer characteristics for the device.

ADS8350 ADS7850 ADS7250 ai_transfer_chara_diff_bas587.gifFigure 51. Ideal Transfer Characteristics