SLDS261A November   2019  – February 2021 TPS6521815

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1. 3.1 Simplified Schematic
  4. 4 Revision History
  5. 5 Description (continued)
  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 Electrical Characteristics
    6. 7.6 Timing Requirements
    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 Wake-Up and Power-Up and Power-Down Sequencing
        1. 8.3.1.1  Power-Up Sequencing
        2. 8.3.1.2  Power-Down Sequencing
        3. 8.3.1.3  Strobe 1 and Strobe 2
        4. 8.3.1.4  Supply Voltage Supervisor and Power-Good (PGOOD)
        5. 8.3.1.5  Backup Supply Power-Good (PGOOD_BU)
        6. 8.3.1.6  Internal LDO (INT_LDO)
        7. 8.3.1.7  Current Limited Load Switches
          1. 8.3.1.7.1 Load Switch 1 (LS1)
          2. 8.3.1.7.2 Load Switch 2 (LS2)
          3. 8.3.1.7.3 Load Switch 3 (LS3)
        8. 8.3.1.8  LDO1
        9. 8.3.1.9  Coin Cell Battery Voltage Acquisition
        10. 8.3.1.10 UVLO
        11. 8.3.1.11 Power-Fail Comparator
        12. 8.3.1.12 Battery-Backup Supply Power-Path
        13. 8.3.1.13 DCDC3 and DCDC4 Power-Up Default Selection
        14. 8.3.1.14 I/O Configuration
          1. 8.3.1.14.1 Configuring GPO2 as Open-Drain Output
          2. 8.3.1.14.2 Using GPIO3 as Reset Signal to DCDC1 and DCDC2
        15. 8.3.1.15 Push Button Input (PB)
          1. 8.3.1.15.1 Signaling PB-Low Event on the nWAKEUP Pin
          2. 8.3.1.15.2 Push Button Reset
        16. 8.3.1.16 AC_DET Input (AC_DET)
        17. 8.3.1.17 Interrupt Pin (INT)
        18. 8.3.1.18 I2C Bus Operation
    4. 8.4 Device Functional Modes
      1. 8.4.1 Modes of Operation
      2. 8.4.2 OFF
      3. 8.4.3 ACTIVE
      4. 8.4.4 SUSPEND
      5. 8.4.5 RESET
    5. 8.5 Programming
      1. 8.5.1 Programming Power-Up Default Values
    6. 8.6 Register Maps
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Applications Without Backup Battery
      2. 9.1.2 Applications Without Battery Backup Supplies
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Output Filter Design
        2. 9.2.2.2 Inductor Selection for Buck Converters
        3. 9.2.2.3 Output Capacitor Selection
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    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

9.2.2.2 Inductor Selection for Buck Converters

The inductor value affects its peak to peak ripple current, the PWM to PFM transition point, the output voltage ripple, and the efficiency. The selected inductor must be rated for its DC resistance and saturation current. The inductor ripple current (∆L) decreases with higher inductance and increases with higher VIN or VOUT. Equation 1 calculates the maximum inductor current ripple under static load conditions. The saturation current of the inductor should be rated higher than the maximum inductor current as calculated with Equation 2. This is recommended as during heavy load transient the inductor current will rise above the calculated value.

Equation 1. GUID-415C0783-BE22-41B2-8F07-63F229B5F74A-low.gif
Equation 2. GUID-D000A20C-97E0-45AB-ACB6-973C008CBB58-low.gif

where

  • F = Switching frequency
  • L = Inductor value
  • ∆IL = Peak-to-peak inductor ripple current
  • ILmax = Maximum inductor current

The following inductors have been used with the TPS6521815 (see Table 9-2).

Table 9-2 List of Recommended Inductors
PART NUMBERVALUESIZE (mm) [L × W × H]MANUFACTURER
INDUCTORS FOR DCDC1, DCDC2, DCDC3, DCDC4
SPM3012T-1R5M1.5 µH, 2.8 A, 77 mΩ3.2 × 3.0 × 1.2TDK
IHLP1212BZER1R5M111.5 µH, 4.0 A, 28.5 mΩ3.6 × 3.0 × 2.0Vishay
INDUCTORS FOR DCDC5, DCDC6
MLZ2012N100L10 µH, 110 mA, 300 mΩ2012 / 0805 (2.00 × 1.25 × 1.25)TDK
LQM21FN100M8010 µH, 100 mA, 300 mΩ2012 / 0805 (2.00 × 1.25 × 1.25)Murata