DAC104S085-Q1: May DAC104S085-Q1 can process 4 channels 60Hz~25KHz waveform at the same time?

Hi Chen,

Thank you for your query. The maximum update rate possible with DAC104S085-Q1 is 1.8MHz in the worst case 1/(t_SYNC+t_SS+t_CFSR). If we divide that by 4, we get an update rate of 453kHz per channel assuming separate writes per channel. Now the frequency of the output waveform will depend on how many points are there. For example, if you have a 10-point sinewave, you can generate a waveform of 45kHz frequency on each of the channels. For a 25kHz sinewave, you can have 18 points. This is from the digital side. However, the output frequency will be mainly limited by the settling time. The worst-case settling time of this part is 6us. For generating a 25kHz sinewave, you can only have 6 points per cycle. If that is ok with you, you can go ahead. or else you need to use a lower settling time device like TLV5627.

You can go through this training video for more details on the update rate:

training.ti.com/lessons-precision-dacs-settling-time-vs-update-rate

Hope that answers your question.

Regards,
Uttam Sahu
Applications Engineer, Precision DACs

Hi Roger,

If you have, say, 'x' points for the 60Hz waveforms, that is '2x' points for two channels. You can use 'y' number of points for 25kHz.

Consider an update rate of 1.8MHz as calculated in my previous post. With this, you can have 1.8MHz/25kHz = 72 points. When you have 3 channels, although you are not updating all the channels all the time, the max update rate will be 1.8MHz/3 = 600kHz. At this rate, you will get 600kHz/25kHz = 24 points for the 25kHz waveform. You need to update the other two channels in between without disturbing the update rate of the 25kHz waveform (that's why 1.8MHz/3). However, if you can tolerate a marginal phaseshift between the 60Hz channels and update them one after another in adjacent cycles, you can get a better update rate of 1.8MHz/2 = 900kHz. This will give you 900kHz/25kHz = 36 points for the 25kHz waveform.

The THD data for this DAC is available only at 10kHz, not at 60Hz. But the values might be close.

Hope that answers your question.

Regards,
Uttam

Hi Roger,

Please click the "resolved" button so that the thread is properly closed.

Regards,
Uttam