SLVT216 July   2024 TPS546C25 , TPS546E25

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2General
    1. 2.1 No Immediate Disable From Soft Start
    2. 2.2 Power Stage Over Temperature Protect
    3. 2.3 Negative Current Limit
    4. 2.4 Programmable Reference DAC gain low
  6. 3Security
    1. 3.1 Standard Write Protection Does Not Work on Secondary Device
    2. 3.2 Device Does Not NACK Incorrect Passkey Per PMBus 1.5
    3. 3.3 Device Does Not Alternate Between Lock and Unlock When Passkey is Written Multiple Times
  7. 4Stacking Interface and Operation of P2_PLUS_Commands
    1. 4.1 Inconsistent P2_PLUS_(various) NACKing by Secondary Device
    2. 4.2 IOUT_OC_FAULT_LIMIT Not Readable on Secondary Device Via P2_PLUS_READ
    3. 4.3 STACK_CONFIG Writable When Should be Read Only
    4. 4.4 Secondary Device ACK's Write to Some Read-Only Registers
    5. 4.5 Secondary Device NACKs All P2_PLUS_WRITE Commands With PHASE = 0xFF
    6. 4.6 Secondary Asserts IVD for P2_PLUS_READ of ALERT_MASK_(various) With PHASE = 0xFF
    7. 4.7 Secondary Device NACKing P2_PLUS_(various) With Valid PHASE
    8. 4.8 Invalid PAGE is ACKed for P2_PLUS_READ Command
  8. 5PMBUS
    1. 5.1 READ_IOUT Data Format is Not Correct
    2. 5.2 OPERATION Not changing VOUT_SOURCE When OFF = b’1
    3. 5.3 PIN_DETECT_OVERRIDE Power-On Source Control Inverted
    4. 5.4 PIN_DETECT_OVERRIDE Bit 15 OVRD_STACK is Not Working Correctly
    5. 5.5 STATUS_OTHER FRST_2_ALRT Does Not Assert STATUS_BYTE or STATUS_WORD Other Bit 0
    6. 5.6 Clamping VOUT by VREF Range Not setting VOUT_MAX_MIN in STATUS_VOUT
  9. 6Summary
  10. 7References

4.6 Secondary Asserts IVD for P2_PLUS_READ of ALERT_MASK_(various) With PHASE = 0xFF

  • Description: When a P2_PLUS_READ command with PHASE = 0xFF is issued, primary device correctly responds with data and secondary NACKs as expected. However, the secondary device is asserting IVD and SMBAlert from this transaction when the device must be ignoring.
  • System Impact: Improper assertion of IVD and SMBAlert
  • Workaround or Mitigation: Use the unique address for the secondary device instead of P2_PLUS for the specified commands, or ignore faults when using P2_PLUS commands to the specified commands on secondary devices.
  • Disposition: Design fix planned for final silicon.