ZHCSKY4B November   2018  – December 2020 TPS55288

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 I2C Timing Characteristics
    7. 6.7 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  VCC Power Supply
      2. 7.3.2  Operation Mode Setting
      3. 7.3.3  Input Undervoltage Lockout
      4. 7.3.4  Enable and Programmable UVLO
      5. 7.3.5  Soft Start
      6. 7.3.6  Shutdown and Load Discharge
      7. 7.3.7  Switching Frequency
      8. 7.3.8  Switching Frequency Dithering
      9. 7.3.9  Inductor Current Limit
      10. 7.3.10 Internal Charge Path
      11. 7.3.11 Output Voltage Setting
      12. 7.3.12 Output Current Monitoring and Cable Voltage Droop Compensation
      13. 7.3.13 Integrated Gate Drivers
      14. 7.3.14 Output Current Limit
      15. 7.3.15 Overvoltage Protection
      16. 7.3.16 Output Short Circuit Protection
      17. 7.3.17 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 PWM Mode
      2. 7.4.2 Power Save Mode
    5. 7.5 I2C Serial Interface
      1. 7.5.1 Data Validity
      2. 7.5.2 START and STOP Conditions
      3. 7.5.3 Byte Format
      4. 7.5.4 Acknowledge (ACK) and Not Acknowledge (NACK)
      5. 7.5.5 Slave Address and Data Direction Bit
      6. 7.5.6 Single Read and Write
      7. 7.5.7 Multi-Read and Multi-Write
    6. 7.6 Register Maps
      1. 7.6.1 REF Register (Address = 0h, 1h) [reset = 11010010h, 00000000h]
      2. 7.6.2 IOUT_LIMIT Register (Address = 2h) [reset = 11100100h]
      3. 7.6.3 VOUT_SR Register (Address = 3h) [reset = 00000001h]
      4. 7.6.4 VOUT_FS Register (Address = 4h) [reset = 00000011h]
      5. 7.6.5 CDC Register (Address = 5h) [reset = 11100000h]
      6. 7.6.6 MODE Register (Address = 6h) [reset = 00100000h]
      7. 7.6.7 STATUS Register (Address = 7h) [reset = 00000011h]
      8. 7.6.8 Register Summary
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 USB PD Power Supply Detailed Design Procedure
        1. 8.2.2.1 Switching Frequency
        2. 8.2.2.2 Output Voltage Setting
        3. 8.2.2.3 Inductor Selection
        4. 8.2.2.4 Input Capacitor
        5. 8.2.2.5 Output Capacitor
        6. 8.2.2.6 Output Current Limit
        7. 8.2.2.7 Loop Stability
      3. 8.2.3 Application Curves
  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 Device Support
      1. 11.1.1 第三方产品免责声明
    2. 11.2 接收文档更新通知
    3. 11.3 支持资源
    4. 11.4 Trademarks
    5. 11.5 静电放电警告
    6. 11.6 术语表
  12. 12Mechanical, Packaging, and Orderable Information

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8.2.2.5 Output Capacitor

In boost mode, the output capacitor conducts high ripple current. The output capacitor RMS ripple current is given by Equation 15, where the minimum input voltage and the maximum output voltage correspond to the maximum capacitor current.

Equation 15. GUID-26452432-D350-4170-BF71-987B00E9C4EC-low.gif

where

  • ICOUT(RMS) is the RMS current through the output capacitor
  • IOUT is the output current

In this example, the maximum output ripple RMS current is 5.5 A.

The ESR of the output capacitor causes an output voltage ripple given by Equation 16 in boost mode.

Equation 16. GUID-39ED80AE-7444-40A6-8B8D-D37C16BA3863-low.gif

where

  • RCOUT is the ESR of the output capacitance

The capacitance also causes a capacitive output voltage ripple given by Equation 17 in boost mode. When input voltage reaches the minimum value and the output voltage reaches the maximum value, there is the largest output voltage ripple caused by the capacitance.

Equation 17. GUID-8C84891A-10D2-4C97-8037-CF57CEC0EA54-low.gif

Typically, a combination of ceramic capacitors and bulk electrolytic capacitors is needed to provide low ESR, high ripple current, and small output voltage ripple. From the required output voltage ripple, use Equation 16 and Equation 17 to calculate the minimum required effective capacitance of the COUT.