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LM25066/Power Good status register

Tsukui Yusuke
Guru 21930 points
Other Parts Discussed in Thread: LM25066, LM25066A, LM25066IA, LM25066I

Hi,

Could you tell me about LM25066A STATUS_WORD(79h) Power Good status?
Customer is trying to confirm the status by reading 79h.
The default value of Power Good status in the 79h 11bit is 1.
When LM25066 does normal operation, does it become 0 by clearing 1?
Is my understanding correct?

Best Regards,
Yusuke / Japan Disty

  • 0
    TI__Genius 12380 points
    Hi Yusuke,

    When the LM25066 or LM25066A first powers on, the SMBA should go low. The STATUS_WORD register will read some faults (such as MFR bit 12 and Power Good bit 11).

    The purpose of this behavior is for the host system to recognize that something was connected/powered on (the LM25066). Then the host can check the SMBA, discover that LM25066 has been powered on, check for any faults other than the default values (note that bit 3 for VIN_UV_FAULT will be 0 after power is applied), and if there are no other faults then it may issue a "CLEAR FAULTS" command and resume operation.

    Notice the STATUS_MFR_SPECIFIC register has a bit 4 which is used to indicate that all default values have been loaded.

    If this behavior is not desired, the LM25066I or LM25066IA devices are Intel Node Manager compliant and behave slightly differently. When they are powered on, they do not pull the SMBA low. Also, the default values for STATUS_WORD are 0's (except PG initially), and there is no MFR bit 12 within STATUS_WORD (instead, there is a function called "FET FAIL").

    Thanks,
    Alex