ZHCSPB1B November   2021  – July 2022 TPS62441-Q1 , TPS62442-Q1

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements
    7. 7.7 Typical Characteristics
  8. 8 Parameter Measurement Information
    1. 8.1 Schematic
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Precise Enable (EN)
      2. 9.3.2 COMP/FSET
      3. 9.3.3 MODE/SYNC
      4. 9.3.4 Spread Spectrum Clocking (SSC)
      5. 9.3.5 Undervoltage Lockout (UVLO)
      6. 9.3.6 Power-Good Output (PG)
      7. 9.3.7 Thermal Shutdown
    4. 9.4 Device Functional Modes
      1. 9.4.1 Pulse Width Modulation (PWM) Operation
      2. 9.4.2 Power Save Mode Operation (PWM and PFM)
      3. 9.4.3 100% Duty-Cycle Operation
      4. 9.4.4 Current Limit and Short Circuit Protection
      5. 9.4.5 Foldback Current Limit and Short Circuit Protection
      6. 9.4.6 Output Discharge
      7. 9.4.7 Soft Start
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Programming the Output Voltage
      2. 10.1.2 External Component Selection
        1. 10.1.2.1 Inductor Selection
        2. 10.1.2.2 Capacitor Selection
          1. 10.1.2.2.1 Input Capacitor
          2. 10.1.2.2.2 Output Capacitor
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 第三方产品免责声明
    2. 13.2 Documentation Support
      1. 13.2.1 Related Documentation
    3. 13.3 接收文档更新通知
    4. 13.4 支持资源
    5. 13.5 Trademarks
    6. 13.6 Electrostatic Discharge Caution
    7. 13.7 术语表
  14. 14Mechanical, Packaging, and Orderable Information

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10.1.2.1 Inductor Selection

The TPS6244x-Q1 is designed for a nominal 0.47-µH inductor with a switching frequency of typically 2.25 MHz. Larger values can be used to achieve a lower inductor current ripple but they can have a negative impact on efficiency and transient response. Smaller values than 0.47 µH cause a larger inductor current ripple, which causes larger negative inductor current in forced PWM mode at low or no output current. For a higher or lower nominal switching frequency, the inductance must be changed accordingly.

The inductor selection is affected by several effects like the following:

  • Inductor ripple current
  • Output ripple voltage
  • PWM-to-PFM transition point
  • Efficiency

In addition, the inductor selected has to be rated for appropriate saturation current and DC resistance (DCR). Equation 7 calculates the maximum inductor current.

Equation 7. GUID-4F0D3DC8-2030-435E-B616-2E7A317F2EC3-low.gif
Equation 8. GUID-F4CBEDD7-6AA3-4C6F-9A39-9E2168EE9DCA-low.gif

where

  • IL(max) is the maximum inductor current.
  • ΔIL(max) is the peak-to-peak inductor ripple current.
  • Lmin is the minimum inductance at the operating point.

Table 10-1 Typical Inductors
Type Inductance [µH] Current [A](1) For Device Nominal Switching Frequency Dimensions
[L × B × H] mm		 Manufacturer(2)
XEL3520-801ME 0.80 µH, ±20% 2.0 TPS62441-Q1 2.25 MHz 3.5 × 3.2 × 2.0 Coilcraft
XEL3520-561ME 0.56 µH, ±20% 2.4 TPS62441-Q1 2.25 MHz 3.5 × 3.2 × 2.0 Coilcraft
XEL3515-561ME 0.56 µH, ±20% 4.5 TPS62442-Q1 2.25 MHz 3.5 × 3.2 × 1.5 Coilcraft
XFL3012-681ME 0.68 µH, ±20% 2.1 TPS62441-Q1 2.25 MHz 3.0 × 3.0 × 1.2 Coilcraft
XPL2010-681ML 0.68 µH, ±20% 1.5 TPS62441-Q1 2.25 MHz 2 × 1.9 × 1 Coilcraft
DFE252012PD-R68M 0.68 µH, ±20% see data sheet TPS62442-Q1 2.25 MHz 2.5 × 2 × 1.2 Murata
DFE252012PD-R47M 0.47 µH, ±20% see data sheet TPS62442-Q1 2.25 MHz 2.5 × 2 × 1.2 Murata
DFE201612PD-R68M 0.68 µH, ±20% see data sheet TPS62441-Q1 2.25 MHz 2 × 1.6 × 1.2 Murata
DFE201612PD-R47M 0.47 µH, ±20% see data sheet TPS62442-Q1 2.25 MHz 2 × 1.6 × 1.2 Murata
(1) Lower of IRMS at 20°C rise or ISAT at 20% drop.

Calculating the maximum inductor current using the actual operating conditions gives the minimum saturation current of the inductor needed. TI recommends adding a margin of approximately 20%. A larger inductor value is also useful to get lower ripple current, but increases the transient response time and size as well.