SLUSEC8B March   2021  – April 2024 TPS628501 , TPS628502 , TPS628503

PRODUCTION DATA  

  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 Parameter Measurement Information
    1. 7.1 Schematic
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Precise Enable (EN)
      2. 8.3.2 COMP/FSET
      3. 8.3.3 MODE / SYNC
      4. 8.3.4 Spread Spectrum Clocking (SSC)
      5. 8.3.5 Undervoltage Lockout (UVLO)
      6. 8.3.6 Power Good Output (PG)
      7. 8.3.7 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Pulse Width Modulation (PWM) Operation
      2. 8.4.2 Power Save Mode Operation (PWM/PFM)
      3. 8.4.3 100% Duty-Cycle Operation
      4. 8.4.4 Current Limit and Short Circuit Protection
      5. 8.4.5 Foldback Current Limit and Short Circuit Protection
      6. 8.4.6 Output Discharge
      7. 8.4.7 Soft Start
      8. 8.4.8 Input Overvoltage Protection
  10. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Programming the Output Voltage
      2. 9.1.2 Inductor Selection
      3. 9.1.3 Capacitor Selection
        1. 9.1.3.1 Input Capacitor
        2. 9.1.3.2 Output Capacitor
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curves
    3. 9.3 System Examples
      1. 9.3.1 Synchronizing to an External Clock
    4. 9.4 Power Supply Recommendations
    5. 9.5 Layout
      1. 9.5.1 Layout Guidelines
      2. 9.5.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Third-Party Products Disclaimer
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

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

9.1.2 Inductor Selection

The TPS62850x family is designed for a nominal 0.47-µH inductor with a switching frequency of typically 2.25 MHz. 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 0.47 µH cause a larger inductor current ripple, which causes larger negative inductor current in forced PWM mode at low or no output current. For a higher or lower nominal switching frequency, the inductance must be changed accordingly. See Section 6.3 for details.

The inductor selection is affected by several effects like inductor ripple current, output ripple voltage, PWM-to-PFM transition point, and efficiency. In addition, the inductor selected has to be rated for appropriate saturation current and DC resistance (DCR). Equation 7 calculates the maximum inductor current.

Equation 7. GUID-230D7973-3BF7-4776-9B5F-C1FB58945AF5-low.gif
Equation 8. GUID-F0D40771-D097-4512-ACBD-9FA438001843-low.gif

where

  • IL(max) is the maximum inductor current
  • ΔIL(max) is the peak-to-peak inductor ripple current
  • Lmin is the minimum inductance at the operating point
Table 9-1 Typical Inductors
TYPE INDUCTANCE [µH] CURRENT [A](1) FOR DEVICE NOMINAL SWITCHING FREQUENCY DIMENSIONS [LxBxH] mm MANUFACTURER(2)
XFL4015-471ME 0.47 µH, ±20% 3.5 TPS628501 / 502 2.25 MHz 4 × 4 × 1.6 Coilcraft
XFL4015-701ME 0.70 µH, ±20% 3.3 TPS628501 / 502 2.25 MHz 4 × 4 × 1.6 Coilcraft
XEL3520-801ME 0.80 µH, ±20% 2.0 TPS628501 / 502 2.25 MHz 3.5 × 3.2 × 2.0 Coilcraft
XEL3515-561ME 0.56 µH, ±20% 4.5 TPS628501 / 502 2.25 MHz 3.5 × 3.2 × 1.5 Coilcraft
XFL3012-681ME 0.68 µH, ±20% 2.1 TPS628501 / 502 2.25 MHz 3.0 × 3.0 × 1.2 Coilcraft
XPL2010-681ML 0.68 µH, ±20% 1.5 TPS628501 2.25 MHz 2 × 1.9 × 1 Coilcraft
DFE252012PD-R68M 0.68 µH, ±20% see data sheet TPS628501 / 502 2.25 MHz 2.5 × 2 × 1.2 Murata
DFE252012PD-R47M 0.47 µH, ±20% see data sheet TPS628501 / 502 2.25 MHz 2.5 × 2 × 1.2 Murata
DFE201612PD-R68M 0.68 µH, ±20% see data sheet TPS628501 / 502 2.25 MHz 2 × 1.6 × 1.2 Murata
DFE201612PD-R47M 0.47 µH, ±20% see data sheet TPS628501 / 502 2.25 MHz 2 × 1.6 × 1.2 Murata
(1) Lower of IRMS at 20°C rise or ISAT at 20% drop.

Calculating the maximum inductor current using the actual operating conditions gives the minimum saturation current of the inductor needed. A margin of about 20% is recommended to add. A larger inductor value is also useful to get lower ripple current, but increases the transient response time and size as well.