# Hi, i need to know if this DAC-op-amp calculation is ok

• NYAME EPHRAIM
In summary, The conversation is discussing a diagram for a R2R ladder DAC and the discrepancies in the resistor values. The original poster is trying to fill in the values for the ladder circuit, but some values are not practical. The conversation also mentions the difference between a Binary Weighted network and a Ladder network.

## The Attempt at a Solution

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• ephraim summing amp.PNG
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That doesn't look right to me. You also can't get 10V out if the power supplies are +/-9V.

Are you trying to make an R2R ladder DAC?

berkeman said:
That doesn't look right to me. You also can't get 10V out if the power supplies are +/-9V.

Are you trying to make an R2R ladder DAC?
Hi, thanks for the reply, the diagraim was presented that way for me to do the calculations, i have also seen related diagraim online for DAC!

Well, can you explain this first line from your diagram? It doesn't make sense past the 900mV number...

Vout = (9V x 470/4700) = 900mV = 800mV = 8V

And why are the resistor values in your table different from the schematic?

berkeman said:
Well, can you explain this first line from your diagram? It doesn't make sense past the 900mV number...

Vout = (9V x 470/4700) = 900mV = 800mV = 8V

And why are the resistor values in your table different from the schematic?

Hi thanks for the reply. my target is to fill that table, those value of resistor in that ladder circuit we don't have most of the values practically, that's why i had to reduce the 9 to 8.
please take a look at this diagram and cross check.

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• FINAL CHECK EPHRAIM.PNG
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That looks very close. The only problem I see is maybe the units definition for Vout in the last column heading of the table. It is hard to read the image, it shows 'x (something) 100mV'. What does it actually say?

What you have shown is a Binary Weighted network.