SLVSFS6C May   2021  – March 2023 TPS629210-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Thermal Information - DYC Package
    6. 7.6 Electrical Characteristics
    7. 7.7 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 Mode Selection and Device Configuration (MODE/S-CONF Pin)
      2. 8.3.2 Adjustable VO Operation (External Voltage Divider)
      3. 8.3.3 Selectable VO Operation (VSET and Internal Voltage Divider)
      4. 8.3.4 Smart Enable with Precise Threshold
      5. 8.3.5 Power Good (PG)
      6. 8.3.6 Output Discharge Function
      7. 8.3.7 Undervoltage Lockout (UVLO)
      8. 8.3.8 Current Limit and Short Circuit Protection
      9. 8.3.9 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Forced Pulse Width Modulation (PWM) Operation
      2. 8.4.2 Power Save Mode Operation (Auto PFM/PWM)
      3. 8.4.3 AEE (Automatic Efficiency Enhancement)
      4. 8.4.4 100% Duty-Cycle Operation
      5. 8.4.5 Starting into a Prebiased Load
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Custom Design With WEBENCH® Tools
        2. 9.2.2.2 Programming the Output Voltage
        3. 9.2.2.3 External Component Selection
          1. 9.2.2.3.1 Output Filter and Loop Stability
          2. 9.2.2.3.2 Inductor Selection
          3. 9.2.2.3.3 Capacitor Selection
            1. 9.2.2.3.3.1 Output Capacitor
            2. 9.2.2.3.3.2 Input Capacitor
      3. 9.2.3 Application Curves
    3. 9.3 System Examples
      1. 9.3.1 Powering Multiple Loads
      2. 9.3.2 Inverting Buck-Boost (IBB)
    4. 9.4 Power Supply Recommendations
    5. 9.5 Layout
      1. 9.5.1 Layout Guidelines
      2. 9.5.2 Layout Example
      3. 9.5.3 Thermal Considerations
  10. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Third-Party Products Disclaimer
      2. 10.1.2 Development Support
        1. 10.1.2.1 Custom Design With WEBENCH® Tools
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  11. 11Mechanical, Packaging, and Orderable Information
9.2.2.3.2 Inductor Selection

The TPS629210-Q1 is designed for a nominal 2.2-µH inductor. Larger values can be used to achieve a lower inductor current ripple but they can have a negative impact on efficiency and transient response. Smaller values than 2.2 µH cause larger inductor current ripple, which cause larger negative inductor currents in forced PWM mode and higher peak currents at full load. Therefore, they are not recommended at larger voltages across the inductor as it is the case for high input voltages and low output voltages. With low output current in forced PWM mode, this causes a larger negative inductor current peak that can exceed the negative current limit. At low or no output current and small inductor values, the output voltage can therefore not be regulated any more. More detailed information on further LC combinations can be found in the Optimizing the TPS62130/40/50/60 Output Filter Application Note.

The inductor selection is affected by several effects like the following:

  • Inductor ripple current
  • Output ripple voltage
  • PWM-to-PFM transition point
  • Efficiency

In addition, the inductor selected has to be rated for appropriate saturation current and DC resistance (DCR). #GUID-2F0164E6-26E2-4673-B3E9-236F25F9D2C8/GUID-59F21276-9084-4DE2-85A8-AFB9A5BF25B2 calculates the maximum inductor current.

Equation 14. IL(MAX)=IOUT(MAX)+∆IL(MAX)2
Equation 15. ∆IL(MAX)=VOUT×1 - VOUTVIN(MAX)L(MIN) × fSW

where:

  • IL(max) is the maximum inductor current.
  • ΔIL is the peak-to-peak inductor ripple current.
  • L(min) is the minimum effective inductor value.

Calculating the maximum inductor current using the actual operating conditions gives the minimum saturation current of the inductor needed. It is recommended to add a margin of approximately 20%. A larger inductor value is also useful to get lower ripple current, but increases the transient response time and size as well. The following inductors have been used with the TPS629210-Q1 and are recommended for use:

Table 9-4 List of Inductors
Type Inductance [µH] DCR [mΩ] Current [A]#GUID-2F0164E6-26E2-4673-B3E9-236F25F9D2C8/INDNOTE1 Dimensions [L×W×H] mm Manufacturer
DFE252012PD-2R2M#GUID-2F0164E6-26E2-4673-B3E9-236F25F9D2C8/INDNOTE2 2.2 µH, ±20% 84 2.8 2.5 × 2.0 × 1.2 muRata
XGL3530-222ME 2.2 μH, ±20% 20 4.0 3.5 × 3.2 × 3 Coilcraft
XGL4020-222ME 2.2 µH, ±20% 19.5 6.2 4 × 4 × 2.1 Coilcraft
XGL3530-332ME 3.3 μH, ±20% 33 3.3 3.5 × 3.2 × 3 Coilcraft
XGL4020-472ME 4.7 µH, ±20% 43 4.1 4 × 4 × 2.1 Coilcraft
(1) ISAT at 30% drop
(2) For smaller size solutions that do not require maximum efficiency at the full output current

The inductor value also determines the load current at which power save mode is entered:

Equation 16. ILoad(PSM)=12×∆IL