SNVSAU8A June   2017  – February 2024 TPS549B22

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 25-A FET
      2. 6.3.2 On-Resistance
      3. 6.3.3 Package Size, Efficiency and Thermal Performance
      4. 6.3.4 Soft-Start Operation
      5. 6.3.5 VDD Supply Undervoltage Lockout (UVLO) Protection
      6. 6.3.6 EN_UVLO Pin Functionality
      7. 6.3.7 Fault Protections
        1. 6.3.7.1 Current Limit (ILIM) Functionality
        2. 6.3.7.2 VDD Undervoltage Lockout (UVLO)
        3. 6.3.7.3 Overvoltage Protection (OVP) and Undervoltage Protection (UVP)
        4. 6.3.7.4 Out-of-Bounds Operation
        5. 6.3.7.5 Overtemperature Protection
    4. 6.4 Device Functional Modes
      1. 6.4.1 D-CAP3™ Control Mode Topology
      2. 6.4.2 DCAP Control Topology
    5. 6.5 Programming
      1. 6.5.1 Programmable Pin-Strap Settings
        1. 6.5.1.1 Address Selection (ADDR) Pin
        2. 6.5.1.2 VSEL Pin
        3. 6.5.1.3 D-CAP3™ Control Mode Selection
        4. 6.5.1.4 Application Workaround to Support 4-ms and 8-ms SS Settings
      2. 6.5.2 Programmable Analog Configurations
        1. 6.5.2.1 RSP/RSN Remote Sensing Functionality
          1. 6.5.2.1.1 Output Differential Remote Sensing Amplifier
        2. 6.5.2.2 Power Good (PGOOD Pin) Functionality
      3. 6.5.3 PMBus Programming
        1. 6.5.3.1 TPS549B22 Limitations to the PMBUS Specifications
        2. 6.5.3.2 Target Address Assignment
        3. 6.5.3.3 PMBUS Address Selection
        4. 6.5.3.4 Supported Formats
          1. 6.5.3.4.1 Direct Format — Write
          2. 6.5.3.4.2 Combined Format — Read
        5. 6.5.3.5 Stop Separated Reads
        6. 6.5.3.6 Supported PMBUS Commands and Registers
  8. 7 Register Maps
    1. 7.1  OPERATION Register (address = 1h)
    2. 7.2  ON_OFF_CONFIG Register (address = 2h)
    3. 7.3  CLEAR FAULTS (address = 3h)
    4. 7.4  WRITE PROTECT (address = 10h)
    5. 7.5  STORE_DEFAULT_ALL (address = 11h)
    6. 7.6  RESTORE_DEFAULT_ALL (address = 12h)
    7. 7.7  CAPABILITY (address = 19h)
    8. 7.8  VOUT_MODE (address = 20h)
    9. 7.9  VOUT_COMMAND (address = 21h)
    10. 7.10 VOUT_MARGIN_HIGH (address = 25h) ®
    11. 7.11 VOUT_MARGIN_LOW (address = 26h)
    12. 7.12 STATUS_BYTE (address = 78h)
    13. 7.13 STATUS_WORD (High Byte) (address = 79h)
    14. 7.14 STATUS_VOUT (address = 7Ah)
    15. 7.15 STATUS_IOUT (address = 7Bh)
    16. 7.16 STATUS_CML (address = 7Eh)
    17. 7.17 MFR_SPECIFIC_00 (address = D0h)
    18. 7.18 MFR_SPECIFIC_01 (address = D1h)
    19. 7.19 MFR_SPECIFIC_02 (address = D2h)
    20. 7.20 MFR_SPECIFIC_03 (address = D3h)
    21. 7.21 MFR_SPECIFIC_04 (address = D4h)
    22. 7.22 MFR_SPECIFIC_06 (address = D6h)
    23. 7.23 MFR_SPECIFIC_07 (address = D7h)
    24. 7.24 MFR_SPECIFIC_44 (address = FCh)
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 TPS549B22 1.5-V to 18-V Input, 1-V Output, 25-A Converter
      2. 8.2.2 Design Requirements
      3. 8.2.3 Detailed Design Procedure
        1. 8.2.3.1  Custom Design With WEBENCH® Tools
        2. 8.2.3.2  Switching Frequency Selection
        3. 8.2.3.3  Inductor Selection
        4. 8.2.3.4  Output Capacitor Selection
          1. 8.2.3.4.1 Minimum Output Capacitance to Make Sure of Stability
          2. 8.2.3.4.2 Response to a Load Transient
          3. 8.2.3.4.3 Output Voltage Ripple
        5. 8.2.3.5  Input Capacitor Selection
        6. 8.2.3.6  Bootstrap Capacitor Selection
        7. 8.2.3.7  BP Pin
        8. 8.2.3.8  R-C Snubber and VIN Pin High-Frequency Bypass
        9. 8.2.3.9  Optimize Reference Voltage (VSEL)
        10. 8.2.3.10 MODE Pin Selection
        11. 8.2.3.11 ADDR Pin Selection
        12. 8.2.3.12 Overcurrent Limit Design
      4. 8.2.4 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Examples
      3. 8.4.3 Mounting and Thermal Profile Recommendation
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Development Support
        1. 9.1.1.1 Custom Design With WEBENCH® Tools
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • RVF|40
Thermal pad, mechanical data (Package|Pins)
Orderable Information
8.2.3.4.2 Response to a Load Transient

The output capacitance must supply the load with the required current when current is not immediately provided by the regulator. When the output capacitor supplies load current, the impedance of the capacitor greatly affects the magnitude of voltage deviation (such as undershoot and overshoot) during the transient.

Use Equation 8 and Equation 9 to estimate the amount of capacitance needed for a given dynamic load step and release.

Note:

There are other factors that can impact the amount of output capacitance for a specific design, such as ripple and stability.

Equation 8. GUID-58B881FD-F8A8-4227-938C-4909FE9A8E44-low.gif
Equation 9. GUID-D7705307-AF70-415D-99FB-A65B762CAC59-low.gif

where

  • COUT(min_under) is the minimum output capacitance to meet the undershoot requirement
  • COUT(min_over)is the minimum output capacitance to meet the overshoot requirement
  • L is the output inductance value (0.33 µH)
  • ∆ILOAD(max) is the maximum transient step (15 A)
  • VOUT is the output voltage value (1 V)
  • tSW is the switching period (1.54 µs)
  • VIN(min) is the minimum input voltage for the design (10.8 V)
  • tOFF(min) is the minimum off time of the device (300 ns)
  • ∆VLOAD(insert) is the undershoot requirement (30 mV)
  • ∆VLOAD(release) is the overshoot requirement (30 mV)

Most of the above parameters can be found in Table 8-1.

The minimum output capacitance to meet the undershoot requirement is 516 µF. The minimum output capacitance to meet the overshoot requirement is 1238 µF. This example uses a combination of POSCAP and MLCC capacitors to meet the overshoot requirement.

  • POSCAP bank 1: 2 x 470 µF, 2.5 V, 6 mΩ per capacitor
  • MLCC bank 2: 7 × 100 µF, 2.5 V, 1 mΩ per capacitor with DC+AC derating factor of 60%

Recalculating the worst case overshoot using the described capacitor bank design, the overshoot is 29.0 mV which meets the 30-mV overshoot specification requirement.