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ONET4291PA: About Register Initial Values for the ONET 4291 PA and ONET 4291 VA

user6150189
Intellectual 460 points
Part Number: ONET4291PA
Other Parts Discussed in Thread: ONET4291VA,

Could you tell me the initial value (default value) of Register0,1,2 of ONET4291VA?


Also, could you tell me the initial value (Default Value) of Register 4, 5 of ONET 4291 PA?

(Assuming use without writing to Register)

  • 0
    TI__Guru* 93670 points

    Greetings,

    I apologize for the late response. I had to do some search on this.

    ONET4291VA register settings are all zero at startup. ONET4291PA is expected to be the same - all registers are set to zero at startup. Please initialize register settings for these two devices after the power cycle.

    Regards,, Nasser

  • 0 in reply to Nasser Mohammadi
    Prodigy 10 points

    This response seems to contradict behavior described in the ONET4291PA datasheet.  The datasheet states that the default output amplitude for the device is 800 mV (see page 10).  Given this, if you look at the register definition you will see that the output amplitude selection bits are required to be non-zero to achieve this output amplitude.

    Either the answer above is incorrect, or the datasheet is incorrect about the default output amplitude.  Would it be possible for TI to specify this behavior in the datasheet?

  • 0 in reply to Ryan Kingsbury
    TI__Guru* 93670 points

    Hi Ryan,

    Both ONET4291VA and ONET4291PA use the same core block for I2C interface. Please note page 7 of the ONET4291VA: "The ONET4291VA has power on reset circuitry which ensures that all registers are reset to zero during startup. After the power-on to initialize time (TINIT1), the internal registers are ready to be loaded." Also please note in ONET4291PA page 10 especifies 800mV "selected(default"). There used to be a GUI for ONET4291PA which enabled 800mV. Please note GUI image - which is no longer supported - below. This enable the user to select 800mV or other VODs.

    Regards,, Nasser