Datasheet

Host Processor Interface
3-10
Table 3–6.Bipolar Operation Output Jumper Settings
Reference
Jumper
Setting
Function
W7 2–3 Select 5 V for the positive rail supply of U12 if W12 is closed
W8 2–3 Select –5 V for the negative supply rail of U12 if W12 is closed
W10 Closed Connect V
REF
to the negative input of op-amp for negative biasing
W11 Open Disconnect R12
W12 Close
Supplies the constant 5 V to the positive rail of U12 and is also fed into the negative
input of U17 to generate an output voltage of –5 V.
W13 3–4 Buffered output of DAC is channeled to the output terminals
An example in Figure 3–8 shows the sinusoid signal in channel 1 being
amplified within the range of ±V
REF
shown in channel 2. The reference
voltage, V
REF
, is set to 5 V, which is then supplied to the negative input of U12
to bias the circuit to its negative rail. This provides an output of ±5 V with 0000h
corresponding to a –5-V output and FFFFh corresponding to 5-V output.
The output voltage for any input code can be calculated as follows:
V
O
+
ƪ
V
REF
ǒ
D
65536
Ǔ ǒ
R1 ) R2
R1
Ǔ
* VREF
ǒ
R2
R1
Ǔ
ƫ
where D represents the input code in decimal (0 – 65536).
With V
REF
= 5 V, R1 = R2 = 10 kΩ:
V
O
+
ǒ
10 D
65536
Ǔ
* 5V
Figure 3–8. DAC8531 Bipolar Output of Operation
DAC8531 Output
Bipolar Output
Similarly, adjusting the V
REF
voltage to any desired value less than 5 V
produces a voltage output range of ±V
REF
.