ZHCSOO0C september   2021  – june 2023 TPS7A94

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  5. 4 Revision History
  6. 5 Pin Configuration and Functions
  7. 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
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Output Voltage Setting and Regulation
      2. 7.3.2 Ultra-Low Noise and Ultra-High Power-Supply Rejection Ratio (PSRR)
      3. 7.3.3 Programmable Current Limit and Power-Good Threshold
      4. 7.3.4 Programmable Soft Start (NR/SS Pin)
      5. 7.3.5 Precision Enable and UVLO
      6. 7.3.6 Active Discharge
      7. 7.3.7 Thermal Shutdown Protection (TSD)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Operation
      2. 7.4.2 Dropout Operation
      3. 7.4.3 Disabled
      4. 7.4.4 Current-Limit Operation
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1  Output Voltage Restart (Overshoot Prevention Circuit)
      2. 8.1.2  Precision Enable (External UVLO)
      3. 8.1.3  Undervoltage Lockout (UVLO) Operation
      4. 8.1.4  Dropout Voltage (VDO)
      5. 8.1.5  Power-Good Feedback (FB_PG Pin) and Power-Good Threshold (PG Pin)
      6. 8.1.6  Adjusting the Factory-Programmed Current Limit
      7. 8.1.7  Programmable Soft-Start and Noise-Reduction (NR/SS Pin)
      8. 8.1.8  Inrush Current
      9. 8.1.9  Optimizing Noise and PSRR
      10. 8.1.10 Adjustable Operation
      11. 8.1.11 Paralleling for Higher Output Current and Lower Noise
      12. 8.1.12 Recommended Capacitor Types
      13. 8.1.13 Load Transient Response
      14. 8.1.14 Power Dissipation (PD)
      15. 8.1.15 Estimating Junction Temperature
      16. 8.1.16 TPS7A94EVM-046 Thermal Analysis
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Board Layout
        2. 8.4.1.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Development Support
        1. 9.1.1.1 Evaluation Modules
        2. 9.1.1.2 Spice Models
      2. 9.1.2 Device Nomenclature
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 接收文档更新通知
    4. 9.4 支持资源
    5. 9.5 Trademarks
    6. 9.6 静电放电警告
    7. 9.7 术语表
  11. 10Mechanical, Packaging, and Orderable Information
    1. 10.1 Mechanical Data

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机械数据 (封装 | 引脚)
  • DSC|10
散热焊盘机械数据 (封装 | 引脚)
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8.1.4 Dropout Voltage (VDO)

The dropout voltage refers to the minimum voltage difference between the input and output voltage (VDO = VIN – VOUT) that is required for regulation. When the input voltage (VIN) drops to or below the maximum dropout voltage (VDO(Max)) for the given load current, see the Electrical CharacteristicsElectrical CharacteristicsElectrical CharacteristicsElectrical CharacteristicsElectrical CharacteristicsElectrical CharacteristicsElectrical Characteristics table, the device functions as a resistive switch and does not regulate the output voltage. When the device is operating in dropout, the output voltage tracks the input voltage. For high current, the dropout voltage (VDO) is proportional to the output current because the device is operating as a resistive switch. For low current, internal nodes are saturating and the dropout plateaus to the minimum value. As mentioned in the Output Voltage Restart (Overshoot Prevention Circuit)Output Voltage Restart (Overshoot Prevention Circuit) section, transient events such as an input voltage brownout, heavy load transient, or short-circuit event can trigger the overshoot prevention circuit. Operating the device at or near dropout significantly degrades both transient performance and PSRR, and can also trigger the overshoot prevention circuit. Maintaining sufficient operating headroom (VOpHr = VIN – VOUT) significantly improves the device transient performance and PSRR, and prevents triggering the overshoot prevention circuit.

Note:

For this device, the pass element is not the limiting dropout voltage factor. Because the reference voltage is generated by a current source and the NR/SS resistor, and because the operating headroom is reducing (even at low load), the internal current source (INR/SS) saturates faster than the pass transistor. This behavior is described in the dropout voltage plot (Figure 6-43). Notice that the dropout does not go to 0 V at light loads.