DAC7741Y Burr-Brown Corporation, DAC7741Y Datasheet - Page 15

• Manufacturer Part Number: DAC7741Y
• Description: 16-Bit/ Single Channel DIGITAL-TO-ANALOG CONVERTER With Internal Reference and Parallel Interface
• Manufacturer: Burr-Brown Corporation

DAC RESET
The RST and RSTSEL inputs control the reset of the analog
output. The reset command is level triggered by a low signal on
RST. Once RST is LOW, the DAC output will begin settling to
the mid-scale or min-scale code depending on the state of the
RSTSEL input. A HIGH value on RSTSEL will cause V
reset to the mid-scale code (8000H) and a LOW value will reset
V
RSTSEL input while RST is LOW will cause a corresponding
change in the reset command selected internally and conse-
quently change the output value of V
a valid reset signal also resets the input register of the DAC to
the value specified by the state of RSTSEL.
GAIN AND OFFSET CALIBRATION
The architecture of the DAC7741 is designed in such a way
as to allow for easily configurable offset and gain calibration
using a minimum of external components. The DAC7741
has built-in feedback resistors and output amplifier summing
points brought out of the package in order to make the
absolute calibration possible. Figures 5 and 6 illustrate the
relationship of offset and gain adjustments for the DAC7741
in a unipolar configuration and in a bipolar configuration,
respectively.
When calibrating the DAC output, offset should be adjusted
first to avoid first order interaction of adjustments. In unipolar
mode, the DAC7741 offset is adjusted from code 0000
for either bipolar mode, offset adjustments are made at code
8000
each configuration, where the output of the DAC should be
at +10V for the 0V to +10V – 1LSB or 10V output range and
+5V – 1LSB for the 5V output range. Figure 7 shows the
generalized external offset and gain adjustment circuitry
using potentiometers.
FIGURE 7. Generalized External Calibration Circuitry for Gain and Symmetrical Offset Adjustment.
DAC7741
OUT
SBAS248A
H
to min-scale (0000
. Gain adjustment can then be made at code FFFF
H
). A change in the state of the
Optional Gain
R
OUT
POT1
Adjust
of the DAC. Note that
(Other Connections Omitted
for Clarity)
15
16
17
18
REF
REFADJ
REF
NC
OUT
OUT
IN
H
H
and
for
www.ti.com
to
FIGURE 5.
FIGURE 6.
R
Optional Offset
Zero Scale
POT2
R
Input =
0000
(AGND)
1
Adjust
Offset Adjust Translates the Line
H
+ Full
Scale
+
V
–
OADJ
1LSB
Relationship of Offset and Gain Adjustments for
V
Relationship of Offset and Gain Adjustments
for V
(Same theory applies for V
OUT
R
S
OUT
= 0V to +10V Output Configuration.
1LSB
(+V
Input =
0000
+ Full Scale
= –10V to +10V Output Configuration.
(+V
REF
Digital Input
I
SJ
H
)
REF
or +V
Input = 8000
Digital Input
– Full-Scale
(–V
Gain Adjust
REF
the Line
Rotates
REF
/2)
OR –V
H
the Line
Rotates
Input =
FFFF
Adjust
OUT
Gain
REF
H
/2)
= –5V to +5V).
Input =
FFFF
Offset
Adjust
Translates
the Line
H
15