SLVSGC5E January   2023  – October 2025 TPS62870 , TPS62871 , TPS62872 , TPS62873

PRODUCTION DATA  

  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 Timing Requirements
    8. 6.8 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 Range
        2. 7.3.6.2 Output Voltage Setpoint
        3. 7.3.6.3 Non-Default Output Voltage Setpoint
        4. 7.3.6.4 Dynamic Voltage Scaling
      7. 7.3.7  Compensation (COMP)
      8. 7.3.8  Mode Selection and 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 Standalone or Primary Device Behavior
        2. 7.3.14.2 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
      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 Register Map
  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 Inductor
        2. 9.2.2.2 Selecting the Input Capacitors
        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, CC
        6. 9.2.2.6 Selecting the Compensation Capacitor, CC2
      3. 9.2.3 Application Curves
    3. 9.3 Best Design Practices
    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

9.2.2.2 Selecting the Input Capacitors

As with all buck converters, the input current of the TPS6287x devices is discontinuous. The input capacitors provide a low-impedance energy source for the device, and the value, type, and location are critical for correct operation. TI recommends low-ESR multilayer ceramic capacitors for best performance. In practice, the total input capacitance is typically comprised of a combination of different capacitors, in which larger capacitors provide the decoupling at lower frequencies and smaller capacitors provide the decoupling at higher frequencies.

The TPS6287x devices feature a butterfly layout with two pairs of VIN and GND pins on opposite sides of the package. This allows the input capacitors to be placed symmetrically on the PCB so that the electromagnetic fields generated cancel each other out, thereby reducing EMI.

The duty cycle of the converter is given by:

Equation 9. D=VOUTη×VIN

where

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

Equation 10. D=0.750.9×3.3=0.253

The value of input capacitance needed to meet the input voltage ripple requirements is given by:

Equation 11. 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. Use the maximum value of 11.3A as given for ΔIOUT in Table 9-1
100mV is used as the input voltage ripple target.

Equation 12. CIN=0.253×1-0.253×11.30.1×2.25×106=9.5μF

The value of CIN calculated with Equation 11 is the effective capacitance after all derating, tolerance, and aging effects have been considered. 5µF effective capacitance per input pin is required. TI recommends multilayer ceramic capacitors with an X7R dielectric (or similar) for CIN, and these capacitors must be placed as close to the VIN and GND pins as possible to minimize the loop area.

Table 9-4 lists a number of capacitors that are an excellent choice for this application. This list is not exhaustive and other capacitors from other manufacturers can also be an excellent choice.

Table 9-3 List of Recommended Input Capacitors
CAPACITANCE DIMENSIONSVOLTAGE RATINGMANUFACTURER, PART NUMBER(1)
MM (INCH)
470nF ±10%1005 (0402)10VMurata, GCM155C71A474KE36D
470nF ±10%1005 (0402)10VTDK, CGA2B3X7S1A474K050BB
10μF ±10%2012 (0805)10VMurata, GCM21BR71A106KE22L
10μF ±10%2012 (0805)10VTDK, CGA4J3X7S1A106K125AB
22μF ±10%3216 (1206)10VMurata, GCM31CR71A226KE02L
22μF ±20%3216 (1206)10VTDK, CGA5L1X7S1A226M160AC