ZHCSEI2B January   2016  – June 2021 TPS7A84

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 Pin Configurations 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 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Low-Noise, High-PSRR Output
      2. 7.3.2  Integrated Resistance Network (ANY-OUT)
      3. 7.3.3  Bias Rail
      4. 7.3.4  Power-Good Function
      5. 7.3.5  Programmable Soft-Start
      6. 7.3.6  Internal Current Limit (ILIM)
      7. 7.3.7  Enable
      8. 7.3.8  Active Discharge Circuit
      9. 7.3.9  Undervoltage Lockout (UVLO)
      10. 7.3.10 Thermal Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation with 1.1 V ≤ VIN < 1.4 V
      2. 7.4.2 Operation with 1.4 V ≤ VIN ≤ 6.5 V
      3. 7.4.3 Shutdown
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1  Recommended Capacitor Types
      2. 8.1.2  Input and Output Capacitor Requirements (CIN and COUT)
      3. 8.1.3  Noise-Reduction and Soft-Start Capacitor (CNR/SS)
      4. 8.1.4  Feed-Forward Capacitor (CFF)
      5. 8.1.5  Soft-Start and In-Rush Current
      6. 8.1.6  Optimizing Noise and PSRR
      7. 8.1.7  Charge Pump Noise
      8. 8.1.8  ANY-OUT Programmable Output Voltage
      9. 8.1.9  ANY-OUT Operation
      10. 8.1.10 Increasing ANY-OUT Resolution for LILO Conditions
      11. 8.1.11 Current Sharing
      12. 8.1.12 Adjustable Operation
      13. 8.1.13 Sequencing Requirements
        1. 8.1.13.1 Sequencing with a Power-Good DC-DC Converter Pin
        2. 8.1.13.2 Sequencing with a Microcontroller (MCU)
      14. 8.1.14 Power-Good Operation
      15. 8.1.15 Undervoltage Lockout (UVLO) Operation
      16. 8.1.16 Dropout Voltage (VDO)
      17. 8.1.17 Behavior when Transitioning from Dropout into Regulation
      18. 8.1.18 Load Transient Response
      19. 8.1.19 Negatively-Biased Output
      20. 8.1.20 Reverse Current Protection
      21. 8.1.21 Power Dissipation (PD)
      22. 8.1.22 Estimating Junction Temperature
      23. 8.1.23 Recommended Area for Continuous Operation (RACO)
    2. 8.2 Typical Applications
      1. 8.2.1 Low-Input, Low-Output (LILO) Voltage Conditions
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Typical Application for a 5.0-V Rail
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Board Layout
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
        1. 11.1.1.1 Evaluation Modules
        2. 11.1.1.2 Spice Models
      2. 11.1.2 Device Nomenclature
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 接收文档更新通知
    4. 11.4 支持资源
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 术语表
  12. 12Mechanical, Packaging, and Orderable Information

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7.3.1 Low-Noise, High-PSRR Output

The TPS7A84 includes a low-noise reference and error amplifier ensuring minimal noise during operation. The NR/SS capacitor (CNR/SS) and feed-forward capacitor (CFF) are the easiest way to reduce device noise. CNR/SS filters the noise from the reference and CFF filters the noise from the error amplifier. The noise contribution from the charge pump is minimal. The overall noise of the system at low output voltages can be reduced by using a bias rail because this rail provides more headroom for internal circuitry.

The high power-supply rejection ratio (PSRR) of the TPS7A84 ensures minimal coupling of input supply noise to the output. The PSRR performance is primarily results from a high-bandwidth, high-gain error amplifier and an innovative circuit to boost the PSRR between 200 kHz and 1 MHz.

The combination of a low noise-floor and high PSRR ensure that the device provides a clean supply to the application; see the Section 8.1.6 section for more information on optimizing the noise and PSRR performance.