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AMC6821: FAN_FAULT Signal Assertion & Deassertion

arulmani v
Prodigy 70 points
Part Number: AMC6821


Hi TI team,

In my card i am using AMC6821 IC and using 4 wire Fan, whenever Fan is not present, Fan Fault signal is not going Low,

Added the 10K Pullup resistor in the schematics for the Fan_fault signal.

Attaching the config registers and values hereby,
00 - B5
01 - 3F
3F - 82
04 - 88

Please do the needful ASAP.

Regards,

Arulmani V

  • 0
    TI__Mastermind 43975 points

    Hi Arulmani,

    Are you unplugging the fan after start-up? 

    What is the contents of the Status registers (0x02/0x03) before and after unplug?

    What is the TACH Low limit (0x10/0x11) relative to the TACH Data (0x080x09)?

    You are using FDRC=01 Software-RPM Control Mode. Does the fan operate as expected? What is the value in TACH Setting (0x1E/0x1F) and does it match TACH Data (0x08/0x09)?

    ren

  • 0 in reply to Ren Schackmann
    Prodigy 70 points

    Are you unplugging the fan after start-up?

     --> Yes

    What is the contents of the Status registers (0x02/0x03) before and after unplug?
    In both the cases values are 0x02 is 28 and 0x03 is 20

    What is the TACH Low limit (0x10/0x11) relative to the TACH Data (0x080x09)?
    TACH Low limit will be always 0x10 is FF 0x11 also FF in both the cases.
    Do we need to set this register?

    You are using FDRC=01 Software-RPM Control Mode. Does the fan operate as expected? What is the value in TACH Setting (0x1E/0x1F) and does it match TACH Data (0x08/0x09)?
    Yes , this we have verified.

  • 0 in reply to arulmani v
    TI__Mastermind 43975 points

    You need to set a TACH Low Limit to trigger the FANS bit to flag the issue. Fan-Fault detection only happens during spin-up. Remember that a large tach value corresponds to a slow fan. The default tach low limit will not trigger FANS bit.

    thanks,

    ren