Replacement for MCP4822 DAC

[joshco]

Hello,
Is it possible to replace a DAC MCP4822 by an other DAC.
MAX 517, for instance...
Its the analog/digital converter of a Midi/CV interface.

What are the main characteristics to look for, to find a replacement?

Thanks
Best regards
T.

[Narbotic]

Looks like you can "request a sample" or just order one straight from Microchip's site - http://www.microchipdirect.com/ProductSearch.aspx?Keywords=MCP4822

I use the MCP4921 a lot - love 'em

[joshco]

Thanks! definitely worth to check out. In the meantime I have read lot of stuff about d/a conversion in general, but not enough. If somebody has some useful links about resistor asessment for dac´s,
I´m also interested...

[Narbotic]

not sure I follow you, do you mean an R2R DAC / Resistor Ladder?

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[joshco]

Yes the R2R Ladder. As longterm Project a have some ideas around the PIC microcontroller, I´m quite at the beginning of programming and µC´s.
At the moment I try to understand DAC´s, in general. If I have a 12Bit ladder it would be easy to quantize CV´s to the appropriate Voltage Steps of 0,0833V. But without an IC-DAC it would need 12 pins for the R2R Ladder. Whereas the IC only needs 3 lines.
I think to experiment with some DAC´s is the next thing do.
As i see, its also possible to convert CV´s with PWM, don´t know about the resolution since it only delivers less than 12Bit, unless I´m mistaken....

[daverj]

remember that an R2R ladder is only as good as the tolerance of the resistors. 1% resistors will give you about 7 bits of accuracy. 0.1% resistors will be good to about 10 bits. For 12 bits you'll need to buy tighter tolerance resistors.

[joshco]

yes, 0.1% resistors will do the job for experimenting with this ciruit. For a stable Midi CV interface, i´ll take the mcp dac.