SNVSBZ5 March   2021 TPS92360

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  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 Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Soft Start-Up
      2. 7.3.2 Open LED Protection
      3. 7.3.3 Shutdown
      4. 7.3.4 Current Program
      5. 7.3.5 LED Brightness Dimming
      6. 7.3.6 Undervoltage Lockout
      7. 7.3.7 Thermal Foldback and Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation with CTRL
  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 Detailed Design Procedure
        1. 8.2.2.1 Inductor Selection
        2. 8.2.2.2 Schottky Diode Selection
        3. 8.2.2.3 Output Capacitor Selection
        4. 8.2.2.4 LED Current Set Resistor
        5. 8.2.2.5 Thermal Considerations
      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
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.2.2.1 Inductor Selection

The selection of the inductor affects power efficiency, steady state operation as well as transient behavior and loop stability. These factors make it the most important component in power regulator design. There are three important inductor specifications, inductor value, DC resistance and saturation current. Considering inductor value alone is not enough. The inductor value determines the inductor ripple current. Choose an inductor that can handle the necessary peak current without saturating. Follow Equation 3 to Equation 4 to calculate the peak current of the inductor. To calculate the current in the worst case, use the minimum input voltage, maximum output voltage and maximum load current of application. In a boost regulator, the input DC current can be calculated as Equation 3.

Equation 3. GUID-38C36151-0C89-4424-AAE7-18A74362650A-low.gif

where

  • VOUT = boost output voltage
  • IOUT = boost output current
  • VIN = boost input voltage
  • η = power conversion efficiency

The inductor current peak to peak ripple can be calculated as Equation 4.

Equation 4. GUID-B188FCFF-51FD-4C61-866F-206848067432-low.gif

where

  • ΔIL(PP) = inductor peak-to-peak ripple
  • L = inductor value
  • FS = boost switching frequency
  • VOUT = boost output voltage
  • VIN = boost input voltage

Therefore, the peak current IL(P) seen by the inductor is calculated with Equation 5.

Equation 5. GUID-EBBD2EA7-BA99-48C7-84C9-9E953384F198-low.gif

Inductor values can have ±20% tolerance with no current bias. When the inductor current approaches saturation level, its inductance can decrease 20% to 35% from the 0-A value depending on how the inductor vendor defines saturation current. Using an inductor with a smaller inductance value forces discontinuous PWM when the inductor current ramps down to zero before the end of each switching cycle. This reduces the boost converter’s maximum output current, causes large input voltage ripple and reduces efficiency. Large inductance value provides much more output current and higher conversion efficiency. For these reasons, a 4.7-μH to 10-μH inductor value range is recommended, and 4.7-μH inductor is recommended for higher than 5-V input voltage by considering inductor peak current and loop stability. Table 8-2 lists the recommended inductor for the TPS92360.

Table 8-2 Recommended Inductors for TPS92360
PART NUMBERL (µH)DCR MAX (mΩ)SATURATION CURRENT (A)SIZE (L x W x H mm)VENDOR
LPS4018-472ML4.71251.94 × 4 × 1.8Coilcraft
LPS4018-103ML102001.34 × 4 × 1.8Coilcraft
PCMB051H-4R7M4.78545.4 × 5.2 × 1.8Cyntec
PCMB051H-100M1015535.4 × 5.2 × 1.8Cyntec