SLVSFS6A May   2021  – September 2021 TPS629210-Q1

ADVANCE INFORMATION  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Device Comparison Table
  6. Pin Configuration and Functions
  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 Electrical Characteristics
  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 Settable 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 Undervoltage Lockout (UVLO)
      7. 8.3.7 Current Limit and Short Circuit Protection
      8. 8.3.8 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Forced Pulse Width Modulation (PWM) Operation
      2. 8.4.2 AEE (Automatic Efficiency Enhancement)
      3. 8.4.3 Power Save Mode Operation (Auto PFM/PWM)
      4. 8.4.4 100% Duty-Cycle Operation
      5. 8.4.5 Output Discharge Function
      6. 8.4.6 Starting into a Pre-Biased Load
  9. Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 External Component Selection
        1. 9.1.1.1 Programming the Output Voltage
        2. 9.1.1.2 Inductor Selection
        3. 9.1.1.3 Capacitor Selection
          1. 9.1.1.3.1 Output Capacitor
          2. 9.1.1.3.2 Input Capacitor
        4. 9.1.1.4 Output Filter and Loop Stability
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
      1. 11.2.1 Thermal Considerations
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support 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

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 will cause a larger inductor current ripple, which causes larger negative inductor current in Forced PWM mode at low or no output current. Therefore, they are not recommended at large 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 Optimizing the TPS62130/40/50/60 Output Filter Application Report.

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). Equation 14 calculates the maximum inductor current.

Equation 14. GUID-144415F5-5D5E-4C22-B948-8C699B860FCA-low.gif
Equation 15. GUID-E4A56C62-6731-423A-A13F-9DC01010C324-low.gif

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 about 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 9-1 List of Inductors
TYPE INDUCTANCE [µH] DCR [mΩ] CURRENT [A](1) DIMENSIONS [L×B×H] mm MANUFACTURER
DFE252012PD-2R2M 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
XGL4020-472ME 4.7 µH, ±20% 43 4.1 4 × 4 × 2.1 Coilcraft
ISAT at 30% drop.

The inductor value also determines the load current at which Power Save mode is entered:

Equation 16. GUID-B5C90AA6-5A33-4C70-8FFA-24DE55D3F1F7-low.gif