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DAC80501: REF-ALARM bit always set when DAC is power enabled

Patanit Sanpitak
Prodigy 30 points
Part Number: DAC80501

Application:

Design: DAC80501ZDGSR, VDD = 3.3V, I2C Mode, A0 tie to SCL, use Internal REF

REF-ALARM bit of Reg 0x07 always set at power up and Vout = 0 (regardless of value load into Reg 0x08)

On Power up, this are the Registers reading:

DEVID -> 0x0115
SYNC -> 0x0100
CONFIG -> 0x0200
GAIN -> 0x0001
TRIGGER -> 0x0000
STATUS -> 0001
DAC -> 0x0000

VREF IO pin measured 2.5V.

So far, the only way to clear the REF-ALARM bit is to either Set the REF_PWDWN bit or set the DAC_PWDWN bit in the CONFIG Register.

1) Bit 9 of CONFIG always set, is that OK?

2) What else could be wrong, bad chip?

******************************************************************

REF-ALARM bit. Reads 1 when the difference between the
reference and supply pins is below a minimum analog threshold.
Reads 0 otherwise.

3) What is this minimum analog Threshold value?

  • 0
    TI__Mastermind 18546 points

    Hi,

    Whats the supply voltage for DAC? 

    We have specific requirements for the internal reference buffer headroom requirements. Please see the table below to configure the REF_DIV bit according to the supply, This conditions are applicable even if you are using internal reference. Failure to do so will trigger REF_ALARM bit.

    Regards,

    AK

  • 0 in reply to Akhilesh K
    Prodigy 30 points

    Hi AK,

    The details of the application was included my first text note.

    I'm repeating it here below:

    Application:

    Design: DAC80501ZDGSR, VDD = 3.3V, I2C Mode, A0 tie to SCL, use Internal REF

    In any case, thank you for the explanation, The REF-DIV bit has to be set to 1 for internal VREF of 2.5V, all good now.

    Thank you for your help.

    Regards,

    PS