DAC80 Burr-Brown Corporation, DAC80 Datasheet - Page 8

• Manufacturer Part Number: DAC80
• Description: Monolithic 12-Bit DIGITAL-TO-ANALOG CONVERTERS
• Manufacturer: Burr-Brown Corporation

TABLE III. Output Voltage Range Connections for Voltage
CURRENT OUTPUT MODELS
The resistive scaling network and equivalent output circuit
of the current model differ from the voltage model and are
shown in Figures 7 and 8.
FIGURE 7. Internal Scaling Resistors.
FIGURE 8. Current Output Model Equivalent Output Circuit.
Internal scaling resistors (Figure 7) are provided to scale an
external op amp or to configure load resistors for a voltage
output. These connections are described in the following
sections.
If the internal resistors are not used for voltage scaling,
external R
Driving An External Op Amp
The current output model DAC80 will drive the summing
junction of an op amp used as a current-to-voltage converter
to produce an output voltage. See Figure 9.
where I
feedback resistor. Using the internal feedback resistors of
25ppm/ C or less to minimize drift. This will typically add
50ppm/ C plus the TCR of R
0 to +10V
0 to +5V
Output
Range
Reference Input
2.5V
2mA
0 to
10
5
OUT
16
18
15
+
–
L
Input Codes
COB or CTC
COB or CTC
COB or CTC
Models.
is the DAC80 output current and R
®
(or R
Digital
To
Reference
Control
Circuit
CSB
CSB
6.3V
DAC80/80P
F
5k
) resistors should have a TCR of
V
I
NOTE: (1) Resistor Tolerances: ±2% max.
OUT
(1)
Connect Connect
Pin 15 to Pin 17 to Pin 19 to
6.3k
3k
19
18
18
18
18
= I
6.3k
R
6.6k
(1)
O
(1)
OUT
L
21 Common
24 Reference Out
To Reference Control Circuit
(or R
x R
17 Bipolar Offset
20
20
20
21
21
F
16 Reference Input
F
15 I
2k
) to the total drift.
Connect
(1)
OUT
NC
NC
15
20
20
19
20
17
Pin 16 to
Connect
F
is the
24
24
24
24
24
8
FIGURE 9. External Op-Amp—Using Internal Feedback
the current output model DAC80 provides output voltage
ranges the same as the voltage model DAC80. To obtain the
desired output voltage range when connecting an external op
amp, refer to Table IV.
TABLE IV. Voltage Range of Current Output.
Output Larger Than 20V Range
For output voltage ranges larger than 10V, a high voltage
op amp may be employed with an external feedback resistor.
Use I
–2mA for unipolar voltage ranges. See Figure 10. Use
protection diodes when a high voltage op amp is used.
The feedback resistor, R
ficient as low as possible. Using an external feedback
resistor, overall drift of the circuit increases due to the lack
of temperature tracking between R
resistor network. This will typically add 50ppm/ C plus R
drift to total drift.
FIGURE 10. External Op-Amp—Using External Feedback
0 to +10V
0 to +5V
Output
Range
2.5V
+
–
10V
5V
OUT
5k
I
0 to
2mA
6.3k
OUT
value of 1mA for bipolar voltage ranges and
Input Codes
Resistors.
COB or CTC
COB or CTC
COB or CTC
Resistors.
Digital
5k
2mA
0 to
CSB
CSB
I
NOTE: (1) For output voltage swings up to 290V p-p.
6.6k
6.3k
6.6k
Connect Connect
F
, should have a temperature coef-
21
A to
24
21
19
19
18
18
18
18
18
17
16
15
15
Pin 17 to Pin 19 to
20V Range
10V Range
F
15
15
15
21
21
and the internal scaling
NOTE: (1) For fast settling.
OPA604
Connect
BB3582J
NC
NC
15
15
A
(1)
R
F
(1)
Connect
Pin 16 to
V
V
24
24
24
24
24
OUT
A
OUT
F