May the AD7845 works with a single supply ?
It cannot , this is a very old part, you may want to take a look at AD5445 which is a 12-bit MDAC, parallel interface and no negative supply needed for the part.
The things is, the AD7845 is used in our designs for years with a single supply +15V and it doesn't seem there are problem with it.
But when I looked at the datasheet, I saw the troubles. I'm currently working about a new design with a correct DAC and supply.
With the confirmation that the AD7845 isn't guaranteed with a single supply we either need a solution to replace to replace the AD7845 on older design.
As the Vss basically supplies the negative supply of the output buffer to create negative output voltages, but looks like your design has a 4-quadrant multiplication configuration and does not intend to output negative values. Again, this might work but there's no guarantee on the performance of the part.
Have you taken a look at the AD5445? Let me know if you have questions please.
We finally choose the AD5725 which works with single voltage +15V, isn'it ?
We test one with :
- AVdd = +15V
- AVss = 0V
- DGND = 0V
- Vrefp =+10V
- Vrefn = 5V
According to the datasheet we're in the specifications.
We want the conversions at a specific time with the first DAC, so we cable the circuit like that :
The datas come from logic circuit 4516, W/R is normally high (+15V) and is active low (0V) to have the conversions.
During the test, we observe that pins already have voltage when not connected.
Cause of that, we have high current with pins we want at +15V and need a resistor, even for DBXX input.
Is that normal ? Cause of the Double-buffered inputs ? iCMOS® process technology ?
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