SLVSAX2B September   2011  – June 2020 TPS61170-Q1

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
    1.     Device Images
      1.      Typical Application
  4. Revision History
  5. Pin Configuration and Functions
    1.     Pin Functions
  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 Switching Characteristics
    7. 6.7 Typical Characteristics
  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 Overcurrent Protection
      3. 7.3.3 Undervoltage Lockout
      4. 7.3.4 Thermal Shutdown
      5. 7.3.5 Enable and Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 PWM Program Mode
      2. 7.4.2 1-Wire Program Mode
      3. 7.4.3 EasyScale
    5. 7.5 Programming
      1. 7.5.1 Feedback Reference Program Mode Selection
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 12-V to 24-V DC-DC Power Conversion
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Program Output Voltage
          2. 8.2.1.2.2 Maximum Output Current
          3. 8.2.1.2.3 Switch Duty Cycle
          4. 8.2.1.2.4 Inductor Selection
          5. 8.2.1.2.5 Schottky Diode Selection
          6. 8.2.1.2.6 Compensation Capacitor Selection
          7. 8.2.1.2.7 Input and Output Capacitor Selection
        3. 8.2.1.3 Application Curve
      2. 8.2.2 5-V to 12-V DC-DC Power Conversion With Programmable Feedback Reference Voltage
      3. 8.2.3 12-V SEPIC (Buck-Boost) Converter
  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. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    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

Inductor Selection

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 (DCR) and saturation current. Considering inductor value alone is not enough.

The inductance value of the inductor determines its ripple current. TI recommends setting the peak-to-peak ripple current given by Equation 3 to 30% to 40% of the DC current. Inductance values shown in the Recommended Operating Conditions table are recommended for most applications. Inductor DC current can be calculated as

Equation 6. TPS61170-Q1 q6_iindc_lvs789.png

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 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, inductors with large inductance and low DCR values provide much more output current and higher conversion efficiency. Inductors with smaller inductance values can give better load transient response. For these reasons, a 10-μH to 22-μH inductance value range is recommended. Table 4 lists some recommended inductors for the TPS61170-Q1.

TPS61170-Q1 device 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 become unstable. Therefore, customers must verify operation in their application if the inductor is different from the recommended values.

Table 4. Recommended Inductors for TPS61170-Q1

PART NUMBER L
(μH)
DCR MAX
(mΩ)
SATURATION CURRENT
(A)
SIZE
(L × W × H mm)
VENDOR(1)
A915_Y-100M 10 90 1.3 5.2 × 5.2 × 3 TOKO
VLCF5020T-100M1R1-1 10 237 1.1 5 × 5 × 2 TDK
CDRH4D22/HP 10 144 1.2 5 × 5 × 2.4 Sumida
LQH43PN100MR0 10 247 0.84 4.5 × 3.2 × 2 Murata
See Third-party Products disclaimer