Hey all,
I am working on a fairly high-end power supply design with purposely-exaggerated specifications...just to see what can be done. 1mV resolution on voltage output from 0 - 30V, 1 mA current limit resolution with maximum of 3 amps out, yadda yadda.
Basically, it's a bench top power supply. I wanted it to be digitally-variable and a DAC was going to be employed for this purpose.
I'll use a rock-solid reference and careful layout, low TC/tolerance resistors, low offset opamps, you know...all that.
My issue is with the DAC. On every single datasheet I've seen for DACs that aren't $50 apiece, they claim to have a "zero code error" or "zero code offset" of 1 mV, or 3 mV, or a few LSBs (I'm looking at 16-bit DACs).
My question is: If I want a true zero-output (as in, 100uV if the resolution of my output is to be 1 mV), do these parts exist? Or, what tricks or circuit techniques are used to ensure a nice, linear output for all bit-codes from zero to full-scale?
Alternatively, does anyone have any advice on what other ways there are to implement DAC functionality? Kelvin-Varley dividers are a bit too complex/high end for this, but I have contemplated using PWM...etc.
Thanks much in advance!
Paul
I am working on a fairly high-end power supply design with purposely-exaggerated specifications...just to see what can be done. 1mV resolution on voltage output from 0 - 30V, 1 mA current limit resolution with maximum of 3 amps out, yadda yadda.
Basically, it's a bench top power supply. I wanted it to be digitally-variable and a DAC was going to be employed for this purpose.
I'll use a rock-solid reference and careful layout, low TC/tolerance resistors, low offset opamps, you know...all that.
My issue is with the DAC. On every single datasheet I've seen for DACs that aren't $50 apiece, they claim to have a "zero code error" or "zero code offset" of 1 mV, or 3 mV, or a few LSBs (I'm looking at 16-bit DACs).
My question is: If I want a true zero-output (as in, 100uV if the resolution of my output is to be 1 mV), do these parts exist? Or, what tricks or circuit techniques are used to ensure a nice, linear output for all bit-codes from zero to full-scale?
Alternatively, does anyone have any advice on what other ways there are to implement DAC functionality? Kelvin-Varley dividers are a bit too complex/high end for this, but I have contemplated using PWM...etc.
Thanks much in advance!
Paul