JAJSCY1 January   2017 ADS7029-Q1

PRODUCTION DATA.  

  1. 特長
  2. アプリケーション
  3. 概要
  4. 改訂履歴
  5. Pin Configuration and Functions
  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
    7. 6.7 Switching Characteristics
    8. 6.8 Typical Characteristics
  7. Parameter Measurement Information
    1. 7.1 Digital Voltage Levels
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Reference
      2. 8.3.2 Analog Input
      3. 8.3.3 ADC Transfer Function
      4. 8.3.4 Serial Interface
    4. 8.4 Device Functional Modes
      1. 8.4.1 Offset Calibration
        1. 8.4.1.1 Offset Calibration on Power-Up
        2. 8.4.1.2 Offset Calibration During Normal Operation
  9. Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Low Distortion Charge Kickback Filter Design
        2. 9.2.2.2 Input Amplifier Selection
        3. 9.2.2.3 Reference Circuit
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
    1. 10.1 AVDD and DVDD Supply Recommendations
    2. 10.2 Estimating Digital Power Consumption
    3. 10.3 Optimizing Power Consumed by the Device
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12デバイスおよびドキュメントのサポート
    1. 12.1 ドキュメントのサポート
      1. 12.1.1 関連資料
    2. 12.2 ドキュメントの更新通知を受け取る方法
    3. 12.3 コミュニティ・リソース
    4. 12.4 商標
    5. 12.5 静電気放電に関する注意事項
    6. 12.6 Glossary
  13. 13メカニカル、パッケージ、および注文情報

パッケージ・オプション

メカニカル・データ(パッケージ|ピン)
サーマルパッド・メカニカル・データ
発注情報

Power Supply Recommendations

AVDD and DVDD Supply Recommendations

The ADS7029-Q1 has two separate power supplies: AVDD and DVDD. The device operates on AVDD; DVDD is used for the interface circuits. AVDD and DVDD can be independently set to any value within the permissible ranges. The AVDD supply also defines the full-scale input range of the device. Always set the AVDD supply to be greater than or equal to the maximum input signal to avoid saturation of codes. Decouple the AVDD and DVDD pins individually with 3.3-µF ceramic decoupling capacitors, as shown in Figure 40.

ADS7029-Q1 ai_supply_bas608.gif Figure 40. Power-Supply Decoupling

Estimating Digital Power Consumption

The current consumption from the DVDD supply depends on the DVDD voltage, load capacitance on the SDO line, and the output code. The load capacitance on the SDO line is charged by the current from the SDO pin on every rising edge of the data output and is discharged on every falling edge of the data output. The current consumed by the device from the DVDD supply can be calculated by Equation 3:

Equation 3. IDVDD = C × V × f

where

  • C = Load capacitance on the SDO line
  • V = DVDD supply voltage and
  • f = Number of transitions on the SDO output

The number of transitions on the SDO output depends on the output code, and thus changes with the analog input. The maximum value of f occurs when data output on SDO change at every SCLK. SDO data changing at every SCLK results in an output code of AAh or 55h. For an output code of AAh or 55h at a 2-MSPS throughput, the frequency of transitions on the SDO output is 8 MHz.

For the current consumption to remain at the lowest possible value, keep the DVDD supply at the lowest permissible value and keep the capacitance on the SDO line as low as possible.

Optimizing Power Consumed by the Device

  • Keep the analog supply voltage (AVDD) as close as possible to the analog input voltage. Set AVDD to be greater than or equal to the analog input voltage of the device.
  • Keep the digital supply voltage (DVDD) at the lowest permissible value.
  • Reduce the load capacitance on the SDO output.
  • Run the device at the optimum throughput. Power consumption reduces with throughput.