Datasheet

Host Processor Interface
3-9
EVM Operation
Table 3–5.Capacitive Load Drive Output Jumper Settings
Reference
Jumper
Setting
Function
W7 2–3 Select 5 V for the positive rail supply of the op-amp if W12 is closed
W8 1–2 Negative rail of the op-amp tied to analog GND
W10 Open Disconnect V
REF
from negative input of op-amp
W11
Open
(see Note)
Disconnect R12 (see Note)
W12 Close
Supplies the constant 5 V to the positive rail of the op-amp if W7, pins 2 and 3,
are shorted together
W13 5–6 Buffered output of DAC is channeled to the output terminals
Note: If there is a need to incrementally adjust the capacitive load output, replace R12 with a capacitor with the desired capaci-
tance value and close W11.
3.2.3 Bipolar Operation Using the DAC8531
Although the DAC8531 has been designed for single-supply operation, the
bipolar output of operation is implemented using the circuit shown in
Figure 3–7. The output of the circuit is an output voltage range of ±V
REF
. The
rail-to-rail operation at the amplifier output is achievable using an OPA350 as
the output amplifier.
Figure 3–7. Bipolar Operation With the DAC8531
_
+
5 V
–5 V
OPA350
R2
10 kΩ
R1
10 kΩ
U11
V
FB
V
OUT
V
REF
Three-Wire
Serial Interface
0.1 µF10 µF
V
REF
DAC8531
U12
±5 V
The EVM requires an additional ±15-V power supply to provide the supply rails
for the OPA177 op-amp, U17. The ±15-V supply is provided through the J1
connector of the EVM. The 15 V is attached to J1-3 terminal and the –15 V is
attached to J1-1 terminal. The ±15-V supplies are referenced to J1-2 terminal.
The OPA177 op-amp is specifically used to generate the –5-V supply voltage
for the negative rail of the OPA350 op-amp circuit, U12.
The bipolar configuration is accomplished by following the correct jumper
settings according to Table 3–6.