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Renesas Electronics Europe - Knowledgebase

Can you explain the D/A converter of the 38000 series further?

Latest Updated:03/13/2008


(D/A Converter)  Regarding the D/A converter of the 38000 series, the answer to FAQ No.103072 states:
"For example, to output 3V as the D/A output, if the op-amp input impedance is infinity and the internal output resistor R0 is 4kΩ, the DAi pin level will be as follows.
3[V] X 100kΩ/(100kΩ + 4kΩ) = 2.885[V]."

(1) Why is "the internal output resistor R0 is 4kΩ" stated? Is R0 always 4 kΩ? Or has R0 = 4 kΩ been used this time just as an example ?

(2) Is "internal output resistor R0" the resistance between the D/A output pin and the R-2R resistor ? [2008/03/13]


(1) R0 = 4 kΩ is just an example.

(2) Yes.
The internal output resistance R0 is equivalent to the combined resistance of R-2R and the D/A output pin.


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