SLVSCQ9E November   2014  – March 2022 TPS65400

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and 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 Electrical Characteristics
    6. 7.6 System Characteristics
    7. 7.7 Operational Parameters
    8. 7.8 Package Dissipation Ratings
    9. 7.9 Typical Characteristics: System Efficiency
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagrams
    3. 8.3 Feature Description
      1. 8.3.1  Startup Timing and Power Sequencing
        1. 8.3.1.1 Startup Timing
        2. 8.3.1.2 External Sequencing
        3. 8.3.1.3 Internal Sequencing
      2. 8.3.2  UVLO and Precision Enables
      3. 8.3.3  Soft-Start and Prebiased Startup
        1. 8.3.3.1 Analog Soft-Start (Default) and Digital Soft-Start
        2. 8.3.3.2 Soft-Start Capacitor Selection
      4. 8.3.4  PWM Switching Frequency Selection
      5. 8.3.5  Clock Synchronization
      6. 8.3.6  Phase Interleaving
      7. 8.3.7  Fault Handling
      8. 8.3.8  OCP for SW1 to SW4
      9. 8.3.9  Overcurrent Protection for SW1 to SW4 in Current Sharing Operation
      10. 8.3.10 Recovery on Power Loss
      11. 8.3.11 Feedback Compensation
      12. 8.3.12 Adjusting Output Voltage
      13. 8.3.13 Digital Interface – PMBus
      14. 8.3.14 Initial Configuration
    4. 8.4 Device Functional Modes
      1. 8.4.1 CCM Operation Mode
      2. 8.4.2 CCM/DCM Operation Mode
      3. 8.4.3 Current Sharing Mode
    5. 8.5 Programming
      1. 8.5.1 PMBus
        1. 8.5.1.1 Overview
        2. 8.5.1.2 PMBus Protocol
          1. 8.5.1.2.1  PMBus Protocol
          2. 8.5.1.2.2  Transactions (No PEC)
          3. 8.5.1.2.3  Addressing
          4. 8.5.1.2.4  Startup
          5. 8.5.1.2.5  Bus Speed
          6. 8.5.1.2.6  I2CALERT Terminal
          7. 8.5.1.2.7  CONTROL Terminal
          8. 8.5.1.2.8  Packet Error Checking
          9. 8.5.1.2.9  Group Commands
          10. 8.5.1.2.10 Unsupported Features
      2. 8.5.2 PMBus Register Descriptions
        1. 8.5.2.1 Overview
        2. 8.5.2.2 Memory Model
        3. 8.5.2.3 Data Formats
        4. 8.5.2.4 Fault Monitoring
    6. 8.6 Register Maps
      1. 8.6.1 PMBus Core Commands
        1. 8.6.1.1  (00h) PAGE
        2. 8.6.1.2  (01h) OPERATION
        3. 8.6.1.3  (03h) CLEAR_FAULTS
        4. 8.6.1.4  (10h) WRITE_PROTECT
        5. 8.6.1.5  (11h) STORE_DEFAULT_ALL
        6. 8.6.1.6  (19h) CAPABILITY
        7. 8.6.1.7  (78h) STATUS_BYTE
        8. 8.6.1.8  (79h) STATUS_WORD
        9. 8.6.1.9  (7Ah) STATUS_VOUT
        10. 8.6.1.10 (80h) STATUS_MFR_SPECIFIC
        11. 8.6.1.11 (98h) PMBUS_REVISION
        12. 8.6.1.12 (ADh) IC_DEVICE_ID
        13. 8.6.1.13 (AEh) IC_DEVICE_REV
      2. 8.6.2 Manufacturer-Specific Commands
        1. 8.6.2.1  (D0h) USER_DATA_BYTE_00
        2. 8.6.2.2  (D1h) USER_DATA_BYTE_01
        3. 8.6.2.3  (D2h) PIN_CONFIG_00
        4. 8.6.2.4  (D3h) PIN_CONFIG_01
        5. 8.6.2.5  (D4h) SEQUENCE_CONFIG
        6. 8.6.2.6  (D5h) SEQUENCE_ORDER
        7. 8.6.2.7  (D6h) IOUT_MODE
        8. 8.6.2.8  (D7h) FREQUENCY_PHASE
        9. 8.6.2.9  (D8h) VREF_COMMAND
        10. 8.6.2.10 (D9h) IOUT_MAX
        11. 8.6.2.11 (DAh) USER_RAM_00
        12. 8.6.2.12 (DBh) SOFT_RESET
        13. 8.6.2.13 (DCh) RESET_DELAY
        14. 8.6.2.14 (DDh) TON_TOFF_DELAY
        15. 8.6.2.15 (DEh) TON_TRANSITION_RATE
        16. 8.6.2.16 (DFh) VREF_TRANSITION_RATE
        17. 8.6.2.17 (F0h) SLOPE_COMPENSATION
        18. 8.6.2.18 (F1h) ISENSE_GAIN
        19. 8.6.2.19 (FCh) DEVICE_CODE
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Internal Operation Typical Application
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Component Selection
            1. 9.2.1.2.1.1 Output Inductor Selection
            2. 9.2.1.2.1.2 Output Capacitor Selection
          2. 9.2.1.2.2 Internal Operation With Some Switchers Disabled
          3. 9.2.1.2.3 Internal Operation With All Switchers Enabled
          4. 9.2.1.2.4 Example Configuration
          5. 9.2.1.2.5 Unused Switchers
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Current Sharing Typical Application
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
          1. 9.2.2.2.1 Current Sharing Timing Example
      3. 9.2.3 External Sequencing Application
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
          1. 9.2.3.2.1 External Sequencing Through PG Pins
          2. 9.2.3.2.2 External Sequencing Through SW
          3. 9.2.3.2.3 Example Configuration
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
      2. 12.1.2 Related Parts
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Glossary
    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

8.3.3 Soft-Start and Prebiased Startup

The TPS65400 implements a soft-start function that minimizes discharge of the output when starting up in a prebiased condition. Soft-start time, tSS, is set by tON_TRANSITION_RATE (digital soft-start) or by a capacitor connected to the corresponding SSx pin (analog soft-start). In this setup, the SSx pin sources a 5-µA current charging the capacitor, and the voltage at the SSx pin limits the reference voltage at the input of the error amplifier.

At the beginning of the soft-start, the soft-start input to the error amplifier is set to 0. The SSx input is raised gradually and reaches its target value during the time tss. If VFB > VSS, then no switching occurs. After the Soft-Start signal crosses VFB, the switching begins. The first switching pulse is on the low-side FET, which charges the high-side bootstrap capacitor. The unit runs in discontinuous conduction mode (DCM) with the zero-cross detector enabled on the low side (diode emulation). The high-side FET is pulsed according to the error amplifier output on the COMP pin. If the IC is configured for continuous conduction mode (CCM) operation (default), the low-side FET pulses gradually transition to normal CCM operation; at each successive switching cycle, the low-side gate pulse is gradually ramped until full synchronous switching occurs. At this point, the switcher enters normal CCM operation.

GUID-2322E103-75E1-4731-9054-DC4FE5ABE4C4-low.gifFigure 8-5 Soft-Start Under Prebiased Condition and CCM Mode Programmed
GUID-26859310-FD66-42C0-A668-E9D35631EF50-low.gifFigure 8-6 Soft-Start Under Prebiased Condition and DCM Mode Programmed