SLVS893F December   2008  – May 2019 TPS61500

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application Circuit
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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 Switching Frequency
      2. 7.3.2 Soft Start
      3. 7.3.3 Enable and Thermal Shutdown
      4. 7.3.4 Undervoltage Lockout (UVLO)
      5. 7.3.5 Overvoltage Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 PWM Dimming Method
      2. 7.4.2 Analog Dimming Method
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Analog Dimming Method
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Programming the Overvoltage Protection
          2. 8.2.1.2.2 Programming the LED Current
          3. 8.2.1.2.3 Implementing Dimming
          4. 8.2.1.2.4 Computing the Maximum Output Current
          5. 8.2.1.2.5 Selecting the Inductor
          6. 8.2.1.2.6 Selecting the Schottky Diode
          7. 8.2.1.2.7 Selecting the Compensation Capacitor and Resistor
          8. 8.2.1.2.8 Selecting the Input and Output Capacitor
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Pure PWM Dimming Method
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Receiving Notification of Documentation Updates
      3. 11.1.3 Community Resources
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.1.2.5 Selecting the Inductor

The 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.

Inductor values can have ±20% tolerance with no current bias. When the inductor current approaches saturation level, its inductance can falls to some percentage of its 0-A value depending on how the inductor vendor defines saturation current.

Using an inductor with a smaller inductance value forces discontinuous PWM where the inductor current ramps down to zero before the end of each switching cycle. This reduces the maximum output current of the boost converter, causes large input voltage ripple and reduces efficiency. In general, large inductance value provides much more output and higher conversion efficiency. Small inductance value can give better the load transient response. For these reasons, TI recommends a 4.7-μH to 22-μH inductor value range. Table 4 lists the recommended inductor for the TPS61500.

Meanwhile, the TPS61500 can program the switching frequency. Normally, small inductance value is suitable for high frequency and vice versa. The device has built-in slope compensation to avoid sub-harmonic oscillation associated with current mode control. If the inductor value is lower than 4.7 μH, the slope compensation may not be adequate, and the loop can be unstable. Therefore, customers should verify the inductor in their application if it is different from the recommended values.

Table 4. Recommended Inductors for TPS61500

PART NUMBER L (µH) DCR MAX (mΩ) SATURATION CURRENT (A) SIZE (L × W × H mm) VENDOR(1)
D104C2 10 44 3.6 10.4 × 10.4 × 4.8 TOKO
VLF10040 15 42 3.1 10.0 × 9.7 × 4.0 TDK
CDRH105RNP 22 61 2.9 10.5 × 10.3 × 5.1 Sumida
MSS1038 15 50 3.8 10.0 × 10.2 × 3.8 Coilcraft
(1) See Third-Party Products disclaimer.