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TPS55289: TPS55289: reset value of REF register (0/1) does not match datasheet

Peter Kahn
Prodigy 100 points

Part Number: TPS55289

The reset value of the REF register (0/1h) of the TPS55289 when read via I²C is 0x00d2 rather than 0x01a4 as documented in the datasheet. Yet, the output voltage is 5V when setting OE to 1. Apparently, there are two copies of that register pair, one read/set via I²C, the other one actually used for the reference voltage and the first pair is copied into the latter one when writing register 1. It seems that the reset value of the first pair is wrong, whereas the reset value of the second pair (not readable via I²C) is correct. This can be confusing, so a note in the datasheet could help. Or is my specimen of the TPS55289 faulty? (I tried this on only one.)

  • 0
    TI__Mastermind 18290 points

    Hi Peter,

    Thank you for reaching out. TPS55289 control IP doesn’t support read 00h/01h register without writing first. This feature doesn’t influence default settings of the register, so default output voltage is 5V. To read the register value, customer needs to  write the register first.

    Regards,

    Mulin

  • 0 in reply to Mulin Yuan
    Prodigy 100 points

    Maybe the datasheet should be updated to reflect this. There's one good thing to this behavior: if REF is read as 0x00d2 and the output voltage is 5V (assuming INTFB has not been changed), then the device has been reset (unexpectedly).