Datasheet

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THEORY OF OPERATION
D/A SECTION
_
+
Resistor
String
Ref+
Ref-
Reference Voltage
GND
DAC Register
V
(SENSE)
V
OUT
V
OUT
 V
REF

D
65536
RESISTOR STRING
R
R
R
R
V
REF
GND
To Output
Amplifier
DAC8571
SLAS373A – DECEMBER 2002 – REVISED JULY 2003
The architecture of the DAC8571 consists of a string DAC followed by an output buffer amplifier. Figure 27
shows a block diagram of the DAC architecture.
Figure 27. DAC8571 Architecture
The input coding to the DAC8571 is unsigned binary, which gives the ideal output voltage as:
where D = decimal equivalent of the binary code that is loaded to the DAC register; it can range from 0 to 65535.
The resistor string section is shown in Figure 28 . It is simply a divide-by-two resistor, followed by a string of
resistors, each of value R. The code loaded into the DAC register determines at which node on the string the
voltage is tapped off to be fed into the output amplifier by closing one of the switches connecting the string to the
amplifier. Because it is a string of resistors, it is assured monotonic.
Figure 28. Resistor String.
11