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

8.3.8 OCP for SW1 to SW4

The OCP is I2C-programmable and set by the IOUT_MAX command. By default, the peak current IOUT_MAX for SW1 and SW2 is 6 A, and for SW3 and SW4 it is 3 A. When the current reaches this threshold, the unit immediately turns off the high-side FET and keeps the low-side FET off for the remainder of the switching cycle. The following cycle are skipped (high-side FET off, low-side FET off) regardless of the inductor current. If the current in the inductor is still higher than the IOUT_MAX after the skipped cycle, the following cycles are also skipped until the current reach below the IOUT_MAX.

If the IOUT_MAX is reached more than 256 active cycles continuously, the switcher shut downs for 20 ms and restarts. If the switcher is running in interleaved operation, both the switcher that tripped the IOUT_MAX threshold and its interleaved counterpart shut down for 20 ms. After that period of time, the unit restarts and goes through soft-start operation. For very-low duty cycle operation and faulty operation with very-fast current increase during the high-side FET on-time (due to inductor saturation and so forth), OCP is also enforced on the low side to ensure no runaway condition exists.

Table 8-2 Current Limit Options
SWITCHERIOUT_MAX
SW1, SW22 A
3 A
4 A
5 A
6 A (default)
SW3, SW40.5 A
1 A
2 A
3 A (default)

While the converter is shut down following an OCP event spanning more than 256 cycles, the COMP terminal is pulled low for 1.1 ms prior to precharge and re-enabling of the converter. At the same time, the SSx pin is discharged to AGND for 1.1 ms. If the soft-start is digital (SSx pins used as PGOODx outputs), the soft-start value is reset.

GUID-A2DFE109-A986-45A6-B2E5-51D699CAFB23-low.gifFigure 8-11 Inductor Current During Overcurrent Event

At high switching frequency (>1 MHz) and particularly when there is a fault in the converter such as saturation of the inductor, the current sensor might not sense the overcurrent event. To ensure that current protection is provided in all operating scenarios, low-side current sensing is also present to provide overcurrent detection and protection when the low-side FET is on. If over-current is detected when the low-side FET is on, the low-side FET stays on (and the high-side FET off) until the current drops below the threshold. A new cycle will then begin (high side on, low side off) when the next switching cycle occurs as driven by the internal clock derived from the oscillator (internal or external synchronization). A dedicated counter records the low-side OCP events and initiates a shutdown of the converter after 256 OCP event counts. Six consecutive cycles without a low-side OCP event resets the counter.

GUID-18B368C0-A8F8-4FB5-AFAB-6766A0DFB1A5-low.gifFigure 8-12 Inductor Current During Overcurrent Event With Low-Side Detection