ZHCSL70D March   2020  – October 2020 TPS63900

PRODUCTION DATA  

  1. 特性
  2. 应用
  3. 说明
  4. Revision History
  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 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Trapezoidal Current Control
      2. 7.3.2 Device Enable / Disable
      3. 7.3.3 Soft Start
      4. 7.3.4 Input Current Limit
      5. 7.3.5 Dynamic Voltage Scaling
      6. 7.3.6 Device Configuration (Resistor-to-Digital Interface)
      7. 7.3.7 SEL Pin
      8. 7.3.8 Short-Circuit Protection
        1. 7.3.8.1 Current Limit Setting = 'Unlimited'
        2. 7.3.8.2 Current Limit Setting = 1 mA to 100 mA
      9. 7.3.9 Thermal Shutdown
    4. 7.4 Device Functional Modes
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Custom Design with WEBENCH Tools
        2. 8.2.2.2 Inductor Selection
        3. 8.2.2.3 Output Capacitor Selection
        4. 8.2.2.4 Input Capacitor Selection
        5. 8.2.2.5 Setting The Output Voltage
      3. 8.2.3 Application Curves
  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 Third-Party Products Disclaimer
    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 静电放电警告
    7. 11.7 术语表
  12. 12Mechanical, Packaging, and Orderable Information

封装选项

机械数据 (封装 | 引脚)
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订购信息

Inductor Selection

The inductor selection is affected by several parameters such as inductor ripple current, output voltage ripple, transition point into Power Save Mode, and efficiency. See Table 8-2 for typical inductors.

For high efficiencies, the inductor must have a low DC resistance to minimize conduction losses. Especially at high-switching frequencies, the core material has a high impact on efficiency. When using small chip inductors, the efficiency is reduced mainly due to higher inductor core losses. This needs to be considered when selecting the appropriate inductor. The inductor value determines the inductor ripple current. The larger the inductor value, the smaller the inductor ripple current and the lower the core and conduction losses of the converter. Conversely, larger inductor values cause a slower load transient response. To avoid saturation of the inductor, the peak current for the inductor in steady state operation is calculated using Equation 5. Only the equation which defines the switch current in boost mode is shown, because this provides the highest value of current and represents the critical current value for selecting the right inductor.

Equation 4. GUID-DD6BB9B4-EFA1-4164-9B7F-CA7A266088BB-low.gif
Equation 5. GUID-0225C6B1-3D14-476F-9EF2-6265B6413FE1-low.gif

where:

  • D = Duty Cycle in Boost mode
  • f = Converter switching frequency
  • L = Inductor value
  • η = Estimated converter efficiency (use the number from the efficiency curves or 0.9 as an assumption)

Note:

The calculation must be done for the minimum input voltage in boost mode.

Calculating the maximum inductor current using the actual operating conditions gives the minimum saturation current of the inductor needed. It is recommended to choose an inductor with a saturation current 20% higher than the value calculated using Equation 5. Possible inductors are listed in Table 8-2.

Table 8-2 List of Recommended Inductors
INDUCTOR VALUE [µH](1)SATURATION CURRENT [A]DCR [mΩ]PART NUMBERMANUFACTURERSIZE (LxWxH mm)
2.23.521XFL4020-222MECoilcraft4 x 4 x 2
2.21.772SRN3015TA-2R2MBourns3 x 3 x 1.5
2.23.197DFE252010F-2R2MMurata2.5 x 2 x 1
2.2 2.4 116 DFE201612E-2R2M Murata 2.0 x 1.6 x 1.2
2.2 2.0 190 DFE201210U-2R2M Murata 2.0 x 1.2 x 1.0