SLVSH95 July   2024 TPS546C25

ADVANCE INFORMATION  

  1.   1
  2. Features
  3. Applications
  4. Description
  5. Pin Configuration and Functions
  6. Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
  7. Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  D-CAP4 Control
        1. 6.3.1.1 Loop Compensation
      2. 6.3.2  Internal VCC LDO and Using an External Bias on VCC Pin and VDRV Pin
      3. 6.3.3  Input Undervoltage Lockout (UVLO)
        1. 6.3.3.1 Fixed VCC_OK UVLO
        2. 6.3.3.2 Fixed VDRV UVLO
        3. 6.3.3.3 Programmable PVIN UVLO
        4. 6.3.3.4 Control (CNTL)Enable
      4. 6.3.4  Differential Remote Sense and Internal, External Feedback Divider
      5. 6.3.5  Set the Output Voltage and VORST#
      6. 6.3.6  Start-Up and Shutdown
      7. 6.3.7  Dynamic Voltage Slew Rate
      8. 6.3.8  Set Switching Frequency
      9. 6.3.9  Switching Node (SW)
      10. 6.3.10 Overcurrent Limit and Low-side Current Sense
      11. 6.3.11 Negative Overcurrent Limit
      12. 6.3.12 Zero-Crossing Detection
      13. 6.3.13 Input Overvoltage Protection
      14. 6.3.14 Output Overvoltage and Undervoltage Protection
      15. 6.3.15 Overtemperature Protection
      16. 6.3.16 Telemetry
    4. 6.4 Device Functional Modes
      1. 6.4.1 Forced Continuous-Conduction Mode
      2. 6.4.2 DCM Light Load Operation
      3. 6.4.3 Powering the Device From a 12V Bus
      4. 6.4.4 Powering the Device From a Split-rail Configuration
      5. 6.4.5 Pin Strapping
        1. 6.4.5.1 Programming MSEL1
        2. 6.4.5.2 Programming PMB_ADDR
        3. 6.4.5.3 Programming MSEL2
        4. 6.4.5.4 Programming VSEL\FB
    5. 6.5 Programming
      1. 6.5.1 Supported PMBus Commands
  8. Register Maps
    1. 7.1  Conventions for Documenting Block Commands
    2. 7.2  (01h) OPERATION
    3. 7.3  (02h) ON_OFF_CONFIG
    4. 7.4  (03h) CLEAR_FAULTS
    5. 7.5  (04h) PHASE
    6. 7.6  (09h) P2_PLUS_WRITE
    7. 7.7  (0Ah) P2_PLUS_READ
    8. 7.8  (0Eh) PASSKEY
    9. 7.9  (10h) WRITE_PROTECT
    10. 7.10 (15h) STORE_USER_ALL
    11. 7.11 (16h) RESTORE_USER_ALL
    12. 7.12 (19h) CAPABILITY
    13. 7.13 (1Bh) SMBALERT_MASK
    14. 7.14 (20h) VOUT_MODE
    15. 7.15 (21h) VOUT_COMMAND
    16. 7.16 (22h) VOUT_TRIM
    17. 7.17 (24h) VOUT_MAX
    18. 7.18 (25h) VOUT_MARGIN_HIGH
    19. 7.19 (26h) VOUT_MARGIN_LOW
    20. 7.20 (27h) VOUT_TRANSITION_RATE
    21. 7.21 (29h) VOUT_SCALE_LOOP
    22. 7.22 (2Ah) VOUT_SCALE_MONITOR
    23. 7.23 (2Bh) VOUT_MIN
    24. 7.24 (33h) FREQUENCY_SWITCH
    25. 7.25 (35h) VIN_ON
    26. 7.26 (36h) VIN_OFF
    27. 7.27 (39h) IOUT_CAL_OFFSET
    28. 7.28 (40h) VOUT_OV_FAULT_LIMIT
    29. 7.29 (41h) VOUT_OV_FAULT_RESPONSE
    30. 7.30 (42h) VOUT_OV_WARN_LIMIT
    31. 7.31 (43h) VOUT_UV_WARN_LIMIT
    32. 7.32 (44h) VOUT_UV_FAULT_LIMIT
    33. 7.33 (45h) VOUT_UV_FAULT_RESPONSE
    34. 7.34 (46h) IOUT_OC_FAULT_LIMIT
    35. 7.35 (48h) IOUT_OC_LV_FAULT_LIMIT
    36. 7.36 (49h) IOUT_OC_LV_FAULT_RESPONSE
    37. 7.37 (4Ah) IOUT_OC_WARN_LIMIT
    38. 7.38 (4Fh) OT_FAULT_LIMIT
    39. 7.39 (50h) OT_FAULT_RESPONSE
    40. 7.40 (51h) OT_WARN_LIMIT
    41. 7.41 (55h) VIN_OV_FAULT_LIMIT
    42. 7.42 (60h) TON_DELAY
    43. 7.43 (61h) TON_RISE
    44. 7.44 (64h) TOFF_DELAY
    45. 7.45 (65h) TOFF_FALL
    46. 7.46 (78h) STATUS_BYTE
    47. 7.47 (79h) STATUS_WORD
    48. 7.48 (7Ah) STATUS_VOUT
    49. 7.49 (7Bh) STATUS_IOUT
    50. 7.50 (7Ch) STATUS_INPUT
    51. 7.51 (7Dh) STATUS_TEMPERATURE
    52. 7.52 (7Eh) STATUS_CML
    53. 7.53 (7Fh) STATUS_OTHER
    54. 7.54 (80h) STATUS_MFR_SPECIFIC
    55. 7.55 (88h) READ_VIN
    56. 7.56 (8Bh) READ_VOUT
    57. 7.57 (8Ch) READ_IOUT
    58. 7.58 (8Dh) READ_TEMPERATURE_1
    59. 7.59 (98h) PMBUS_REVISION
    60. 7.60 (99h) MFR_ID
    61. 7.61 (9Ah) MFR_MODEL
    62. 7.62 (9Bh) MFR_REVISION
    63. 7.63 (ADh) IC_DEVICE_ID
    64. 7.64 (AEh) IC_DEVICE_REV
    65. 7.65 (D1h) SYS_CFG_USER1
    66. 7.66 (D2h) PMBUS_ADDR
    67. 7.67 (D4h) COMP
    68. 7.68 (D5h) VBOOT_OFFSET_1
    69. 7.69 (D6h) STACK_CONFIG
    70. 7.70 (D8h) PIN_DETECT_OVERRIDE
    71. 7.71 (D9h) NVM_CHECKSUM
    72. 7.72 (DAh) READ_TELEMETRY
    73. 7.73 (79h) STATUS_ALL
    74. 7.74 (DDh) EXT_WRITE_PROTECTION
    75. 7.75 (A4h) IMON_CAL
    76. 7.76 (FCh) FUSION_ID0
    77. 7.77 (FDh) FUSION_ID1
  9. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Application
      2. 8.2.2 Design Requirements
      3. 8.2.3 Detailed Design Procedure
        1. 8.2.3.1 Input Capacitor Selection
        2. 8.2.3.2 Inductor Selection
        3. 8.2.3.3 Output Capacitor Selection
        4. 8.2.3.4 Compensation Selection
        5. 8.2.3.5 VCC and VRDV Bypass Capacitors
        6. 8.2.3.6 BOOT Capacitor Selection
        7. 8.2.3.7 VOSNS and GOSNS Capacitor Selection
        8. 8.2.3.8 PMBus Address Resistor Selection
      4. 8.2.4 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
        1. 8.4.2.1 Thermal Performance on TPS546C25EVM
  10. Device and Documentation Support
    1. 9.1 Receiving Notification of Documentation Updates
    2. 9.2 Support Resources
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information
    1. 11.1 Tape and Reel Information

Package Options

Mechanical Data (Package|Pins)
  • VBD|33
Thermal pad, mechanical data (Package|Pins)
Orderable Information

Start-Up and Shutdown

Start-Up

The start-up and shutdown of the device is controlled by several PMBus programmable values including:

The tON_RISE time is selectable by pin-strapping through MSEL1, PMBus programming, or both.

With the default ON_OFF_CONFIG settings, the timing is as shown. See the Supported PMBus commands for full details on the implementation and use.

TPS546C25 TPS546C25 Start-Up and Shutdown Figure 6-4 TPS546C25 Start-Up and Shutdown

The startup sequence includes three sequential periods. During the first period, the device does initialization, which includes building up internal LDOs and references, register value initialization, pin strap detection, enabling digital interface, and so forth. The initialization, which is not gated by CTRL pin voltage, starts as long as VCC pin voltage is above the VCC_OK UVLO rising threshold (3.15V typical). The length of this period is about 200μs for TPS546C25 device. The PMBus communication including both read and write operations is allowed after finishing the initialization.

Once the CTRL pin voltage crosses above CTRL high threshold (typically 1.2V) the device moves to the second period, power-on delay. The power-on delay is programmable in TPS546C25 through register TON_DELAY with minimum 0.05ms delay and maximum 2ms delay.

The VOUT soft start is the third period. A soft-start ramp, which is an internal signal, starts when the chosen power-on delay finishes. The soft-start time can be selected in register TON_RISE with options of 1ms, 2ms, 4ms, 8ms, and 16ms. When starting up without prebias on the output, the VOUT ramps up from 0V to either the selected Vboot value or the programmable VOUT_COMMAND value to avoid the inrush current by the output capacitor charging, and also minimize VOUT overshoot.

For the startup with a prebiased output the device limits current from being discharged from the prebiased output voltage by preventing the low-side FET from forcing the SW node low until after the first PWM pulse turns on the high-side FET. After the increasing reference voltage exceeds the feedback voltage, which is internally divided down from (VOSNS−GOSNS) level, the high-side SW pulses start. This action enables a smooth start-up with a prebiased output.

Shutdown

The TPS546C25 device also offers programmable soft-stop feature through PMBus register TOFF_FALL with 0.5ms, 1ms, 2ms, and 4ms options. The soft-stop feature forces a controlled decrease of the output voltage from regulation to 200mV. After Vout is discharged to 200mV level the power stage stops switching and goes to tri-state. There can be negative inductor current forced during the TOFF_FALL time to discharge the output voltage.

After a stop condition is received and the selected TOFF_DELAY delay expires, the TPS546C25 device enters the soft-stop operation during which the control loop actively controls the discharge slew rate of the output voltage. The power stage continues switching while the internal reference ramps down linearly. The discharge slew rate during this phase is determined by the selected boot up voltage (not the current output voltage) and the selected TOFF_FALL time. After Vout is discharged to 200mV level the power stage stops switching and goes to tri-state. The Vout discharge continues but the discharge slew rate is controlled by the load current. With this discharge operation, the TPS546C25 device controls the soft-stop slew rate rather the total soft-stop time, thus the total VOUT discharge time (also known as, soft-stop time) can vary from the register TOFF_FALL value. The TOFF_FALL time is utilized to set the internal reference DAC ramp-down time from the regulation level to 0mV. For example, under heavy load condition, the total soft-stop time from VOUT regulation level to zero volt is likely shorter than the programmed TOFF_FALL value. Under light load, the total soft-stop time likely becomes longer than the programmed TOFF_FALL value.