SLVSGS7C July   2023  – April 2024 TPSM8287A06 , TPSM8287A12 , TPSM8287A15

PRODMIX  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Options
  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 I2C Interface Timing Characteristics
    7. 6.7 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Fixed-Frequency DCS-Control Topology
      2. 7.3.2  Forced-PWM and Power-Save Modes
      3. 7.3.3  Precise Enable
      4. 7.3.4  Start-Up
      5. 7.3.5  Switching Frequency Selection
      6. 7.3.6  Output Voltage Setting
        1. 7.3.6.1 Output Voltage Setpoint
        2. 7.3.6.2 Output Voltage Range
        3. 7.3.6.3 Non-Default Output Voltage Setpoint
        4. 7.3.6.4 Dynamic Voltage Scaling (DVS)
      7. 7.3.7  Compensation (COMP)
      8. 7.3.8  Mode Selection / Clock Synchronization (MODE/SYNC)
      9. 7.3.9  Spread Spectrum Clocking (SSC)
      10. 7.3.10 Output Discharge
      11. 7.3.11 Undervoltage Lockout (UVLO)
      12. 7.3.12 Overvoltage Lockout (OVLO)
      13. 7.3.13 Overcurrent Protection
        1. 7.3.13.1 Cycle-by-Cycle Current Limiting
        2. 7.3.13.2 Hiccup Mode
        3. 7.3.13.3 Current-Limit Mode
      14. 7.3.14 Power Good (PG)
        1. 7.3.14.1 Power-Good Standalone, Primary Device Behavior
        2. 7.3.14.2 Power-Good Secondary Device Behavior
      15. 7.3.15 Remote Sense
      16. 7.3.16 Thermal Warning and Shutdown
      17. 7.3.17 Stacked Operation
    4. 7.4 Device Functional Modes
      1. 7.4.1 Power-On Reset (POR)
      2. 7.4.2 Undervoltage Lockout
      3. 7.4.3 Standby
      4. 7.4.4 On
    5. 7.5 Programming
      1. 7.5.1 Serial Interface Description
      2. 7.5.2 Standard-, Fast-, Fast-Mode Plus Protocol
      3. 7.5.3 I2C Update Sequence
      4. 7.5.4 I2C Register Reset
  9. 8 Device Registers
  10. 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 Selecting the Input Capacitors
        2. 9.2.2.2 Selecting the Target Loop Bandwidth
        3. 9.2.2.3 Selecting the Compensation Resistor
        4. 9.2.2.4 Selecting the Output Capacitors
        5. 9.2.2.5 Selecting the Compensation Capacitor, CComp1
        6. 9.2.2.6 Selecting the Compensation Capacitor, CComp2
      3. 9.2.3 Application Curves
    3. 9.3 Typical Application Using Four TPSM8287Axx in Parallel Operation
      1. 9.3.1 Design Requirements
      2. 9.3.2 Detailed Design Procedure
        1. 9.3.2.1 Selecting the Input Capacitors
        2. 9.3.2.2 Selecting the Target Loop Bandwidth
        3. 9.3.2.3 Selecting the Compensation Resistor
        4. 9.3.2.4 Selecting the Output Capacitors
        5. 9.3.2.5 Selecting the Compensation Capacitor, CComp1
        6. 9.3.2.6 Selecting the Compensation Capacitor, CComp2
      3. 9.3.3 Application Curves
    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 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
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
  • RDW|39
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9.2.2.1 Selecting the Input Capacitors

The input capacitor buffers the input voltage for transient events and also decouples the converter from the supply. TI recommends a X7R multilayer ceramic capacitor (MLCC) for best filtering and must be placed between both VIN and GND pins, as close as possible to those pins. For applications with ambient temperatures below 85°C, a capacitor with X5R dielectric can be used. Ceramic capacitors have a DC-Bias effect, which has a strong influence on the final effective capacitance. Choose the right capacitor carefully in combination with considering the package size and voltage rating. The two high frequency input capacitors are placed inside the module to reduce EMI, shrink the overall design size and to simplify the board layout. As those integrated capacitors target high frequencies, additional external capacitors with a minimum of 5 µF are required per VIN pin.

The TPSM8287Axx devices feature a butterfly or parallel layout with two pairs of VIN and GND pins on opposite sides of the package. This feature allows the input capacitors to be placed symmetrically on the PCB so that the electromagnetic fields cancel each other out, thereby reducing EMI. In addition, the parasitic loop inductance between the input capacitors and the IC is reduced through this pinout.

The duty cycle of the converter is given by:

Equation 11. D=VOUTη×VIN

where:

  • VIN is the input voltage
  • VOUT is the output voltage
  • η is the efficiency

Equation 12. D=0.900.83×2.7=0.402

The value of input capacitance needed to meet any system-level input voltage ripple requirement is given by Equation 40. For this example, the lowest input voltage and highest load current are used to generate a worst case input voltage ripple of 100 mV.

Equation 13. CIN=D×(1-D)×IOUTVIN(PP)×fsw

where:

  • D is the duty cycle
  • fsw is the switching frequency
  • L is the inductance
  • IOUT is the output current

Equation 14. CIN=0.402×1-0.402×12.00.1×2.25×106=12.8 μF

The value of CIN calculated with Equation 40 is the effective capacitance after all derating, tolerance, and aging effects have been considered.