SLUSAP2J March   2012  – November 2021 UCD3138

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Functional Block Diagram
  5. 5 Revision History
  6. 6 Device Comparison Table
    1. 6.1 Product Family Comparison
    2. 6.2 Product Selection Matrix
  7. 7 Pin Configuration and Functions
    1. 7.1 UCD3138RGC 64 QFN Pin Attributes
    2. 7.2 UCD3138RHA, UCD3138RMH and UCD3138RJA Pin Attributes
  8. 8 Specifications
    1. 8.1 Absolute Maximum Ratings
    2. 8.2 ESD Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Electrical Characteristics
    6. 8.6 Timing and Switching Characteristics
    7. 8.7 Power Supply Sequencing
    8. 8.8 Peripherals
      1. 8.8.1 Digital Power Peripherals (DPPs)
        1. 8.8.1.1 Front End
        2. 8.8.1.2 DPWM Module
        3. 8.8.1.3 DPWM Events
        4. 8.8.1.4 High Resolution DPWM
        5. 8.8.1.5 Oversampling
        6. 8.8.1.6 DPWM Interrupt Generation
        7. 8.8.1.7 DPWM Interrupt Scaling/Range
    9. 8.9 Typical Temperature Characteristics
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 ARM Processor
    3. 9.3 Memory
      1. 9.3.1 CPU Memory Map and Interrupts
      2. 9.3.2 Boot ROM
      3. 9.3.3 Customer Boot Program
      4. 9.3.4 Flash Management
    4. 9.4 System Module
      1. 9.4.1 Address Decoder (DEC)
      2. 9.4.2 Memory Management Controller (MMC)
      3. 9.4.3 System Management (SYS)
      4. 9.4.4 Central Interrupt Module (CIM)
    5. 9.5 Feature Description
      1. 9.5.1  Sync FET Ramp and IDE Calculation
      2. 9.5.2  Automatic Mode Switching
        1. 9.5.2.1 Phase Shifted Full Bridge Example
        2. 9.5.2.2 LLC Example
        3. 9.5.2.3 Mechanism for Automatic Mode Switching
      3. 9.5.3  DPWMC, Edge Generation, IntraMux
      4. 9.5.4  Filter
        1. 9.5.4.1 Loop Multiplexer
        2. 9.5.4.2 Fault Multiplexer
      5. 9.5.5  Communication Ports
        1. 9.5.5.1 SCI (UART) Serial Communication Interface
        2. 9.5.5.2 PMBUS
        3. 9.5.5.3 General Purpose ADC12
        4. 9.5.5.4 Timers
          1. 9.5.5.4.1 24-bit PWM Timer
          2. 9.5.5.4.2 16-Bit PWM Timers
          3. 9.5.5.4.3 Watchdog Timer
      6. 9.5.6  Miscellaneous Analog
      7. 9.5.7  Package ID Information
      8. 9.5.8  Brownout
      9. 9.5.9  Global I/O
      10. 9.5.10 Temperature Sensor Control
      11. 9.5.11 I/O Mux Control
      12. 9.5.12 Current Sharing Control
      13. 9.5.13 Temperature Reference
    6. 9.6 Device Functional Modes
      1. 9.6.1 Normal Mode
      2. 9.6.2 Phase Shifting
      3. 9.6.3 DPWM Multiple Output Mode
      4. 9.6.4 DPWM Resonant Mode
      5. 9.6.5 Triangular Mode
      6. 9.6.6 Leading Edge Mode
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 PCMC (Peak Current Mode Control) PSFB (Phase Shifted Full Bridge) Hardware Configuration Overview
        2. 10.2.2.2 DPWM Initialization for PSFB
        3. 10.2.2.3 DPWM Synchronization
        4. 10.2.2.4 Fixed Signals to Bridge
        5. 10.2.2.5 Dynamic Signals to Bridge
        6. 10.2.2.6 System Initialization for PCM
          1. 10.2.2.6.1 Use of Front Ends and Filters in PSFB
          2. 10.2.2.6.2 Peak Current Detection
          3. 10.2.2.6.3 Peak Current Mode (PCM)
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
    1. 11.1 Introduction To Power Supply and Layout Recommendations
    2. 11.2 3.3-V Supply Pins
    3. 11.3 Recommendation for V33 Ramp up Slew Rate for UCD3138 and UCD3138064
    4. 11.4 Recommendation for RC Time Constant of RESET Pin for UCD3138 and UCD3138064
  12. 12Layout
    1. 12.1 Layout Guidelines
      1. 12.1.1 EMI and EMC Mitigation Guidelines
      2. 12.1.2 BP18 Pin
      3. 12.1.3 Additional Bias Guidelines
      4. 12.1.4 UCD3138 Pin Connection Recommendation
        1. 12.1.4.1 Current Amplifier With EADC Connection
        2. 12.1.4.2 DPWM Synchronization
        3. 12.1.4.3 GPIOS
        4. 12.1.4.4 DPWM PINS
        5. 12.1.4.5 EAP and EAN Pins
        6. 12.1.4.6 ADC Pins
      5. 12.1.5 UART Communication Port
      6. 12.1.6 Special Considerations
    2. 12.2 Layout Example
      1. 12.2.1 UCD3138 and UCD3138064 40 Pin
      2. 12.2.2 UCD3138 and UCD3138064 64 Pin
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 Code Composer Studio
      2. 13.1.2 Tools and Documentation
    2. 13.2 Documentation Support
      1. 13.2.1 References
    3. 13.3 Receiving Notification of Documentation Updates
    4. 13.4 Support Resources
    5. 13.5 Trademarks
    6. 13.6 Electrostatic Discharge Caution
    7. 13.7 Glossary
  14. 14Mechanical Packaging and Orderable Information
    1. 14.1 Packaging Information

Package Options

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

9.5.1 Sync FET Ramp and IDE Calculation

The UCD3138 has built in logic for controlling MOSFETs for synchronous rectification (Sync FETs). This comes in two forms:

  • Sync FET ramp
  • Ideal Diode Emulation (IDE) calculation

When starting up a power supply, sometimes there is already a voltage on the output – this is called prebias. It is very difficult to calculate the ideal Sync FET on-time for this case. If it is not calculated correctly, it may pull down the prebias voltage, causing the power supply to sink current.

To avoid this, Sync FETs are not turned on until after the power supply has ramped up to the nominal voltage. The Sync FETs are turned on gradually in order to avoid an output voltage glitch. The Sync FET Ramp logic can be used to turn them on at a rate below the bandwidth of the filter.

In discontinuous mode, the ideal on-time for the Sync FETs is a function of Vin, Vout, and the primary side duty cycle (D). The IDE logic in the UCD3138 takes Vin and Vout data from the firmware and combines it with D data from the filter hardware. It uses this information to calculate the ideal on-time for the Sync FETs.