SLVS412F December   2001  – April 2019 TPS54310

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin 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 Dissipation Ratings
    6. 7.6 Electrical Characteristics
    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  Undervoltage Lockout (UVLO)
      2. 8.3.2  Slow Start and Enable (SS/ENA)
      3. 8.3.3  VBIAS Regulator (VBIAS)
      4. 8.3.4  Voltage Reference
      5. 8.3.5  Oscillator and PWM Ramp
      6. 8.3.6  Error Amplifier
      7. 8.3.7  PWM Control
      8. 8.3.8  Dead-Time Control and MOSFET Drivers
      9. 8.3.9  Overcurrent Protection
      10. 8.3.10 Thermal Shutdown
      11. 8.3.11 Powergood (PWRGD)
    4. 8.4 Device Functional Modes
      1. 8.4.1 Continuous Conduction Mode
      2. 8.4.2 Switching Frequency Configuration
  9. 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 Input Voltage
        2. 9.2.2.2 Feedback Circuit
        3. 9.2.2.3 Setting the Output Voltage
        4. 9.2.2.4 Operating Frequency
        5. 9.2.2.5 Output Filter
      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 Related DC/DC Products
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community 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

8.3.5 Oscillator and PWM Ramp

The oscillator frequency can be set to internally fixed values of 350 kHz or 550 kHz using the SYNC pin as a static digital input. If a different frequency of operation is required for the application, the oscillator frequency can be externally adjusted from 280 kHz to 700 kHz by connecting a resistor to the RT pin to ground and floating the SYNC pin. The switching frequency is approximated by the following equation, where R is the resistance from RT to AGND:

Equation 3. TPS54310 q4_sw_f_lvs412.gif

External synchronization of the PWM ramp is possible over the frequency range of 330 kHz to 700 kHz by driving a synchronization signal into SYNC and connecting a resistor from RT to AGND. Choose an RT resistor that sets the free-running frequency to 80% of the synchronization signal. Table 1 summarizes the frequency selection configurations.

Table 1. Summary of the Frequency Selection Configurations

SWITCHING FREQUENCY SYNC PIN RT PIN
350 kHz, internally set Float or AGND Float
550 kHz, internally set ≥ 2.5 V Float
Externally set 280 kHz to 700 kHz Float R = 68 k to 180 k
Externally synchronized frequency Synchronization signal R = RT value for 80% of external synchronization frequency