SLVSD88M July   2016  – August 2026 TPS61099

PRODMIX  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Boost Controller Operation
      2. 7.3.2 Undervoltage Lockout
      3. 7.3.3 Enable and Disable
      4. 7.3.4 Soft Start
      5. 7.3.5 Current Limit Operation
      6. 7.3.6 Output Short-to-Ground Protection
      7. 7.3.7 Overvoltage Protection
      8. 7.3.8 Down Mode Regulation and Pass-Through Operation
      9. 7.3.9 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Burst Mode Operation under Light Load Condition
      2. 7.4.2 Down Mode Regulation and Pass-Through Mode Operation
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application - 5V Output Boost Converter
      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 Programming the Output Voltage
        3. 8.2.2.3 Maximum Output Current
        4. 8.2.2.4 Inductor Selection
        5. 8.2.2.5 Capacitor Selection
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
      2. 9.1.2 Development Support
        1. 9.1.2.1 Custom Design With WEBENCH® Tools
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

8.2.2.4 Inductor Selection

Because the selection of the inductor affects steady state operation, transient behavior, and loop stability, the inductor is the most important component in power regulator design. There are three important inductor specifications, inductor value, saturation current, and dc resistance (DCR).

The TPS61099x is optimized to work with inductor values between 1µH and 2.2µH. For best stability consideration, a 2.2µH inductor is recommended under Vout > 3.0V condition while choosing a 1µH inductor for applications under Vout ≤ 3.0V condition. Follow Equation 3 and Equation 4 to calculate the inductor peak current for the application. Depending on different load conditions, the TPS61099x works in continuous current mode or discontinuous mode. In different modes, the peak currents of the inductor are also different. Equation 3 provides an easy way to estimate whether the device works in CCM or DCM. As long as the Equation 3 is true, continuous current mode is typically established. Otherwise, discontinuous current mode is typically established.

Equation 3. TPS61099

The inductor current ripple ILH is fixed by design. Therefore, Equation 4 calculates the peak inductor current.

Equation 4. TPS61099

where

  • IL,peak is the peak inductor current.

The inductor saturation current must be higher than the calculated peak inductor current. Table 8-2 lists the recommended inductors for TPS61099x device.

After choosing the inductor, Equation 5 calculates the estimated switching frequency ƒ in continuous current mode. The switching frequency is not a constant value, which is determined by L, VIN and VOUT.

Equation 5. TPS61099
Table 8-2 List of Inductors
VOUT [V](1)INDUCTANCE [µH]SATURATION CURRENT [A]DC RESISTANCE [mΩ]SIZE (L × W × H)PART NUMBERMANUFACTURER
> 3.02.21.95802.5 × 2.0 × 1.274404024022Würth Elektronik
2.21.7922.5 × 2.0 × 1.1LQH2HPN2R2MJRmuRata
2.21.451632.0 × 1.6 × 1.0VLS201610Cx-2R2MTDK
≤ 3.01.02.6372.5 × 2.0 × 1.274404024010Würth Elektronik
1.02.3482.5 × 2.0 × 1.0MLP2520W1R0MT0S1TDK
1.01.5802.0 × 1.2 × 1.0LQM21PN1R0MGHmuRata
(1) See the Third-Party Products disclaimer