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TPS546D24S: TPS546D24S Vs TPS546D24A

Part Number: TPS546D24S
Other Parts Discussed in Thread: TPS546D24A,


We have used TPS546D24ARVFR regulators in one of our design and the boards is manufactured and ready for assembly but the TPS546D24A is not available now. Our procurement team is suggesting 2nd source option TPS546D24S.

I can't see any difference between these two parts. What exactly is the difference between these two parts?

TPS546D24S can be used for the replacement of TPS546D24A. Please confirm.

Thank you!!


Gajendiran A 


    The TPS546D24S is a new, Drop In compatible version of the TPS546D24A with some additional PMBus features and improved AVIN UVLO to Enable/PMBus start-up time.

    The IC_DEVICE_ID suffix (last byte) has been updated as a unique identifier for in-system discoverability, but all pin detection resistors and programming options remain the same.  As long as system firmware can tolerate the new IC_DEVICE_ID suffix, it should be drop-in compatible with existing PCBs and programming solutions.

    The new PMBus features are:

    EXT_WRITE_PROTECT which provides the user with greater flexibility in write protecting groups of functionally related PMBus commands to limit configuration changes that will be accepted by the devices, including the ability to prohibit write-access to EXT_WRITE_PROTECT, permanently locking write access to protect the configuration from changes by a malicious actor who has gained access to the PMBus

    PASSKEY which provides a 16-bit passcode.  When a non-zero value is stored to PASSKEY at RESTORE or Power On, the PASSKEY command prevents write access to STORE_USER_ALL and EXT_WRITE_PROTECT, allowing a user to select an intermediate level of protection between permanently locking EXT_WRITE_PROTECT and leaving EXT_WRITE_PROTECT unlocked.  To minimize sensitivity to brute-force attacks, the PASSKEY will disable after 3 failed attempts each AVIN power cycle.

    To improve security, TI recommends customers programming PASSKEY:

    1) Program MFR_MODEL and MFR_SERIAL with unique identifiers

    2) Program PASSKEY with a private-key hash of MFR_MODEL and MFR_ID (and other protected information) in order to use a unique but discoverable PASSKEY for each system.  This will prevent a malicious user who has gained access to 1 device from being able to gain access to all similar devices.

    If EXT_WRITE_PROTECT will not be used, users can program it to 8000h to lock access to EXT_WRITE_PROTECT.