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DAC60504: External Reference

James Colotti
Prodigy 90 points
Part Number: DAC60504

Hello,

The DAC60504 allows for an external reference.

On power up, it defaults to an internal reference of 2.5 VDC and then the part must be configured for an external reference.

It appears that if the external reference is applied (in my case 3.41 VDC), the DAC can be damaged if the current supplied exceeds 10 mA – do I have that correct?

Also only typical values are given for the reference input impedance and leakage – any info on the min/max values?

Thanks,

Jim

  • 0
    TI__Mastermind 28578 points

    Hi Jim, 

    Yes, we recommend using a series resistance to limit the current to 10mA to reduce power consumption and avoid damage/performance degradation due to the repeated high current at power on until the internal reference is disabled. 

    As a note, with a 3.41V external reference you will need to enable the reference divider. If you also enable the output buffer 2x gain your full scale output will be 3.41V. Is this ok for your application? Otherwise, using a 2.5V reference with a VDD > 5V will allow your full scale output to reach 5V. 

    We do not have max/min values for impedance or leakage characterized. 

    Best,

    Katlynne Jones

  • 0 in reply to Katlynne Jones
    Prodigy 90 points

    Hi Katlynne,

    The GAIN and REFDIV are connected to Vio, so the DAC output can be adjusted from 0 to +3.41 VDC - do you agree?

    With no min Rin and no max on leakage for REFIO, there is no way to bound the error introduced by the series resistor - do you agree?

    Thanks,

    Jim

  • 0 in reply to James Colotti
    TI__Mastermind 28578 points

    Hi James, 

    Yes this is correct.

    James Colotti said:
    The GAIN and REFDIV are connected to Vio, so the DAC output can be adjusted from 0 to +3.41 VDC - do you agree?

    That is true. This is not a characterized spec, but a spec promised by design. Assuming a conservative process tolerance of ±5%, the error due to any variation in the input impedance will be less than 1LSB (832uV with your selected reference and 12-bit DAC).

    James Colotti said:
    With no min Rin and no max on leakage for REFIO, there is no way to bound the error introduced by the series resistor - do you agree?

    Best,

    Katlynne Jones