Dear newsgroup community,
recently I came across the following challenge. There are several digital values which I want to convert to analog signals. Ok then, no problem. Simply D/A conversion! But after converting the signals the general set up requires that these values should be held for about - let's say - a period of 5 minutes with practically no droop (decay of the analog value) at best! The D/A conversion itself takes place in a 1 MHz period, the values to be set have to pend for about 5 minues. I guess a hold-element (capacitor and op-amp) would be the obvious choice. But how should I dimension the capacitance and how can I affect the droop? Is it realistic to expect virtually no droop assuming an optimal configuration ? Isn't it, that with a large time constant the charging time would be endless, too? Please help me, if you can. I am almost become desperate. I need this for my graduation report.
Thank you in advance and many greets Veronica