Datasheet
9
®
DAC715
R
3
is a low-resistance ground plane or conductor. In this case
you may wish to connect DCOM to SYSTEM GROUND as
well.
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.
Using D/A Converters
The GAIN ADJUST and OFFSET ADJUST circuits of
the DAC715 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.
Nominal values of GAIN and OFFSET occur when the D/A
converters outputs are at approximately half scale, 0V.
DIGITAL INTERFACE
BUS INTERFACE
The DAC715 has a 16-bit double-buffered data interface
with control lines for easy connection to a 16-bit bus. The
double-buffered feature permits update of several D/As
simultaneously.
A
0
is the enable control for the DATA INPUT LATCH. A
1
is the enable for the D/A LATCH. WR is used to strobe data
into latches enabled by A
0
, and A
1
. Refer to the block
diagram of Figure 1 and to Timing Diagram on page 3.
CLR sets the INPUT DATA LATCH and D/A LATCH to
0000
H
(5V at the D/A output).
SINGLE-BUFFERED OPERATION
FIGURE 5. System Ground Considerations for High-Resolution D/A Converters.
R
1
Sense
Output
R
L
R
2
R
3
Alternate Ground
Sense Connection
System Ground
ACOMDCOM
Bus
Interface
DAC715
Analog
Power
Supply
0.01µF
(1)
0.01µF
To +V
CC
To –V
CC
NOTE: (1) Locate close to DAC715 package.
V
OUT
5kΩ10kΩ
V
REF