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DAC81416: Multiplexed DAC output

Deepak Sharma
Prodigy 235 points
Part Number: DAC81416
Other Parts Discussed in Thread: DAC80508,

Hi

I was curious to understand the block diagram which you have given in the datasheet: My design requirements are the following:

1. Output impedance of a specific active DAC channel (1 among 16 ) should be very low say less than (<0.1 ohm).

2. Output impedance of all other/inactive DAC channels (15 among 16 ) should be very high, say less than (>1G ohm).

3. Programmable selection of a channel for buffered output voltage (0 to 5V) with very low input impedance.

Any help will be appreciated.

Thanks and Regards,

Deepak

  • 0
    TI__Guru 53633 points

    We will review and respond after the US holiday.

  • 0 in reply to Paul_Frost
    TI__Guru 53633 points

    Hi Deepak,

    The DAC81416 meets the first and third requirement, but not the high-impedance output requirement.  Most precision DACs do not have a true high-z shutdown mode.  Usually, we have a limited output impedance shutdown mode, like 100kΩ or 10kΩ.  >1GΩ will be pretty hard to achieve without some kind of external switching, or an output buffer that features a true high-z mode shutdown option.  That might be the best to look at.  You could consider a device like the DAC80508 (5V output max device) and buffer the outputs with op amp that features a shutdown option.  Alternatively you could use some kind of analog switch or relay to ensure very low leakage when the output is disabled.

    Thanks,

    Paul