SLVS790E November   2007  – April 2019 TPS61165

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application
  4. 4 Revision History
  5. 5 Device Options
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 Recommended Operating Conditions
    3. 7.3 Thermal Information
    4. 7.4 Electrical Characteristics
    5. 7.5 Timing Requirements
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Soft Start-Up
      2. 8.3.2 Open LED Protection
      3. 8.3.3 Undervoltage Lockout
      4. 8.3.4 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Maximum Output Current
      2. 9.1.2 Inductor Selection
      3. 9.1.3 Schottky Diode Selection
      4. 9.1.4 Compensation Capacitor Selection
      5. 9.1.5 Input and Output Capacitor Selection
    2. 9.2 Typical Applications
      1. 9.2.1 TPS61165 Typical Application
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 LED Brightness Dimming Mode Selection
          2. 9.2.1.2.2 PWM Brightness Dimming
          3. 9.2.1.2.3 Digital One-Wire Brightness Dimming
          4. 9.2.1.2.4 EasyScale: One-Wire Digital Dimming
          5. 9.2.1.2.5 Current Program
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Additional Application Circuits
    3. 9.3 Do's and Don'ts
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 Thermal Considerations
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9.1.2 Inductor Selection

Selection of the inductor affects 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, according to half of the peak-to-peak ripple current given by Equation 1, pause the inductor DC current given by:

Equation 3. TPS61165 q5_iindc_lvs790.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 0A 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 maximum output current of the boost convert, causes large input voltage ripple, and reduces efficiency. Large inductance value provides much more output current and higher conversion efficiency. For these reasons, a 10-μH to 22-μH inductor value range is recommended. A 22-μH inductor optimized the efficiency for most application while maintaining low inductor peak to peak ripple. Table 2 lists the recommended inductor for the TPS61165. When recommending inductor value, the factory has considered –40% and 20% tolerance from its nominal value.

TPS61165 has built-in slope compensation to avoid subharmonic oscillation associated with current mode control. If the inductor value is lower than 10 μH, the slope compensation may not be adequate, and the loop can be unstable. Therefore, customers need to verify the inductor in their application if it is different from the recommended values.

Table 2. Recommended Inductors for TPS61165

PART NUMBER L
(μH)		 DCR MAX
(mΩ)		 SATURATION CURRENT (A) SIZE
(L × W × H mm)		 VENDOR
A915_Y-100M 10 90 1.3 5.2 × 5.2 × 3.0 TOKO
VLCF5020T-100M1R1-1 10 237 1.1 5 × 5 × 2.0 TDK
CDRH4D22/HP 10 144 1.2 5 × 5 × 2.4 Sumida
LQH43PN100MR0 10 247 0.84 4.5 × 3.2 × 2.0 Murata