±
12V OPERATION
+ Full Scale
Range of
Gain Adjust
1LSB
Analog Output
Full Scale Range
The DAC811 is fully specified for operation on
±12V
power
supplies. However, in order for the output to swing to
±10V,
the power supplies must be
±13.5V
or greater. When oper-
ating with
±12VB
supplies, the output swing should be
restricted to
±8V
in order to meet specifications.
LOGIC INPUT COMPATIBILITY
The DAC811 digital inputs are TTL, LSTTL, and 54/74HC
CMOS-compatible over the operating range of V
DD
. The
input switching threshold remains at the TLL threshold over
the supply range.
The logic input current over temperature is low enough to
permit driving the DAC811 directly from the outputs of
4000B and 54/74C CMOS devices.
Resistors of 47Ω should be placed in series with D0 through
D11, WR, N
A
, N
B
, N
C
and LDAC if edges are <10ns or if
the logic input is driven below ground by undershoot.
Gain Adjust
Rotates the Line
All Bits
Logic 0
Range of
Offset Adj.
All Bits
Logic 1
Digital Input
Offset Adjust Translates the Line
FIGURE 3. Relationship of Offset and Gain Adjustments
for a Unipolar D/A Converter.
INSTALLATION
+ Full Scale
POWER SUPPLY CONNECTIONS
1LSB
Range of
Gain Adjust
Gain Adjust
Rotates the Line
For optimum performance and noise rejection, power supply
decoupling capacitors should be added as shown in Figure 5.
These capacitors (1µF tantalum recommended) should be
located close to the DAC811.
Analog Output
All Bits
Logic 0
Full Scale
Range
Bipolar V
Offset
MSB on All
Others Off
All Bits
Logic 1
Range of
Offset Adjust
Offset Adj.
Translates
the Line
≈ ±0.4%
– Full Scale
V
DD
1
2
V
DD
BPO
Summing
Junction
28
27
26
25
V
OUT
ACOM
24
23
22
21
20
19
18
17
16
DCOM
15
Connect for
Bipolar Operation
–V
CC
1MΩ
10k
Ω
to
100k
Ω
1µF
Digital Input
3
4
5
6
7
FIGURE 4. Relationship of Offset and Gain Adjustments
for a Bipolar D/A Converter.
ANALOG OUTPUT
DIGITAL INPUT
MSB
LSB
↓
↓
111111111111
100000000000
011111111111
000000000000
LSB
0 to +10V
+V
CC
3.9MΩ
10k
Ω
to
100k
Ω
–V
CC
+V
CC
Gain Adjust
–V
CC
+V
CC
8
±
5V
±
10V
9
10
+9.9976V
+5V
+4.9976V
0V
2.4mV
+4.9976V
0V
–0.0024V
–5V
2.44mV
+9.9951V
0V
–0.0049V
–10V
4.88mV
11
12
13
14
0.0022µF
1µF
1µF
TABLE III. Digital Input/Analog Output.
GAIN ADJUSTMENT
For either unipolar or bipolar configurations, apply the
digital input that should give the maximum positive voltage
output. Adjust the gain potentiometer for this positive full
scale voltage. See Table III for positive full scale voltages.
FIGURE 5. Power Supply, Gain, and Offset Potentiometer
Connections.
®
DAC811
6
TI [ TEXAS INSTRUMENTS ]
