there is no change in DAC712 ACOM current, provided that
R3 is a low-resistance ground plane or conductor. In this case
you may wish to connect DCOM to SYSTEM GROUND as
well.
Nominal values of GAIN and OFFSET occur when the D/A
converters outputs are at approximately half scale, +5V.
OUTPUT VOLTAGE RANGE CONNECTIONS
The DAC712 output amplifier is connected internally for the
±10V bipolar (20V) output range. That is, the bipolar offset
resistor is connected to an internal reference voltage and the
20V range resistor is connected internally to VOUT. DAC712
cannot be connected by the user for unipolar operation.
GAIN AND OFFSET ADJUST
Connections Using Potentiometers
GAIN and OFFSET adjust pins provide for trim using
external potentiometers. 15-turn potentiometers provide suf-
ficient resolution. Range of adjustment of these trims is at
least ±0.3% of Full Scale Range. Refer to Figure 6.
DIGITAL INTERFACE
BUS INTERFACE
Using D/A Converters
DAC712 has 16-bit double-buffered data bus interface with
control lines for easy interface to interface to a 16-bit bus.
The double-buffered feature permits update of several D/As
simultaneously.
The GAIN ADJUST and OFFSET ADJUST circuits of
DAC712 have been arranged so that these points may be
easily driven by external D/A converters. Refer to Figure 7.
12-bit D/A converters provide an OFFSET adjust resolution
and a GAIN adjust resolution of 30µV to 50µV per LSB
step.
DAC712
10kΩ
10kΩ
VREF
R1
VOUT
Bus
Interface
Sense
Output
RL
DCOM
ACOM
R2
Alternate Ground
Sense Connection
R3
To +VCC
0.01µF(1)
0.01µF
Analog
Power
Supply
System Ground
To –VCC
NOTE: (1) Locate close to DAC712 package.
FIGURE 5. System Ground Considerations for High-Resolution D/A Converters.
®
10
DAC712
BB [ BURR-BROWN CORPORATION ]
