ZHCSME0B December   2020  – November 2022 TPS7A43

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 Pin Configuration 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 Diagrams
    3. 7.3 Feature Description
      1. 7.3.1 MID_OUT Voltage Selection
      2. 7.3.2 Precision Enable
      3. 7.3.3 Dropout Voltage
      4. 7.3.4 Current Limit
      5. 7.3.5 Thermal Shutdown
      6. 7.3.6 Power Good
    4. 7.4 Device Functional Modes
      1. 7.4.1 Device Functional Mode Comparison
      2. 7.4.2 Normal Operation
      3. 7.4.3 Dropout Operation
      4. 7.4.4 Disabled
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 MID_OUT Voltage Setting
      2. 8.1.2 Adjustable Device Feedback Resistors
      3. 8.1.3 Recommended Capacitor Types
      4. 8.1.4 Input and Output Capacitor Requirements
      5. 8.1.5 Power Dissipation (PD)
      6. 8.1.6 Estimating Junction Temperature
    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
      2. 8.4.2 Layout Examples
  9. 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 Electrostatic Discharge Caution
    7. 9.7 术语表
  10. 10Mechanical, Packaging, and Orderable Information

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8.2.2 Detailed Design Procedure

A fixed 3.3-V output voltage device is used for this application. The MID_OUT voltage is set to 12 V by tying the VMVSEL1 pin to GND and setting VMVSEL2 to ≥ 0.9 V using the R3 and R4 resistor divider. The value of the R3 and R4 divider ratio must ensure that VMVSEL2 is set to ≥ 0.9 V when VIN ≥ 15 V. To limit the current burned through this divider to 5 μA, R3 can be calculated using Equation 10, and the calculated value then can be rounded to the nearest standard value. When VIN goes all the way up to 85 V during a transient, the VMSEL2 voltage goes up to 3.9 V (which is still lower than the maximum recommended value for this pin, as specified in the Section 6.3 table).

Equation 10. R3 = (15 V – 0.9 V) / 5 μA = 2.82 MΩ

R4 then can be calculated with Equation 11 by using the VMVSEL2 value of the same current value.

Equation 11. R3 = 0.9 V / 5 μA = 180 kΩ

The enable precision circuit is also used to turn off the device when VIN drops below 15 V. The R1 and R2 resistor divider is used to set VEN to lower than VEN(LOW) of 1.15 V when VIN drops below 15 V. R1 can be calculated using Equation 12 to limit the burned current through this divider to 5 μA, similar to the above divider.

Equation 12. R1 = (15 V – 1.15 V) / 5 μA = 2.77 MΩ

Equation 13 can then be used to calculate R2. The calculated R1 and R2 values can then rounded to the nearest standard values.

Equation 13. R2 = 1.15 V / 5 μA = 230 kΩ