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

7.4.1 Serial Interface

The devices support a simple, SPI-compatible serial interface to the external digital host. The CS signal defines one conversion and serial transfer frame. A frame starts with a CS falling edge and ends with a CS rising edge. The SDO_A and SDO_B pins output the ADC_A and ADC_B conversion results, respectively. Figure 52 shows a detailed timing diagram for these devices.

ADS8350 ADS7850 ADS7250 ai_serial_if_bas580.gifFigure 52. Serial Interface Timing Diagram

A CS falling edge brings the serial data bus out of 3-state and also outputs a '0' on the SDO_A and SDO_B pins. The device converts the sampled analog input during the next 14 clocks. SDO_A and SDO_B read '0' during this period. The sample-and-hold circuit goes back into sample mode on the 15th SCLK falling edge and the MSBs of ADC_A and ADC_B are output on SDO_A and SDO_B, respectively. The subsequent clock edges are used to shift out the conversion result using the serial interface, as shown in Table 2. Output data are in binary twos complement format. A CS rising edge ends the frame and puts the serial bus into 3-state.

Table 2. Data Launch Edge

DEVICE PIN LAUNCH EDGE
CS ↓ SCLK CS ↑
↓1 … ↓14 ↓15 … ↓26 ↓27 ↓28 ↓29 ↓30 ↓31 …
ADS8350 SDO-A 0 0 … 0 D15_A … D4_A D3_A D2_A D1_A D0_A 0 … Hi-Z
SDO-B 0 0 … 0 D15_B … D4_B D3_B D2_B D1_B D0_B 0 … Hi-Z
ADS7850 SDO-A 0 0 … 0 D13_A … D2_A D1_A D0_A 0 0 0 … Hi-Z
SDO-B 0 0 … 0 D13_B … D2_B D1_B D0_B 0 0 0 … Hi-Z
ADS7250 SDO-A 0 0 … 0 D11_A … D0_A 0 0 0 0 0 … Hi-Z
SDO-B 0 0 … 0 D11_B … D0_B 0 0 0 0 0 … Hi-Z