Texas Instruments DAC8541EVM, Руководство пользователя, Страница: 22 / 26

Host Processor Operation
3-4
Table 3 - 4. Capacitive Load Drive Output Jumper Settings
Reference Jumper Position Function
W3 2 - 3 Negative rail of the op amp tied to analog GND
W4 1 - 2 Positive rail supply of the op amp tied to 15 V
W5 3 - 4 Capacitive load drive output of DAC is channeled to the output terminals
W6 Open Disconnect V
REF(H)
from negative input of op amp
W7 Open Disconnect R8 (see Note)
Note: If there is a need to incrementally adjust the capacitive load output, replace R8 with a capacitor with the desired capaci-
tance value and CLOSE W7.
3.2.4 Bipolar Operation Using the DAC8541 (Default Mode)
Although the DAC8541 is designed for single-supply operation, the bipolar
output of operation is implemented using the circuit shown in Figure 3 - 1. The
output of the circuit gives an output voltage range of
±
V
REF(H)
. The rail-to-rail
operation at the amplifier output is achievable using an OPA627 as the output
amplifier.
Figure 3 - 1. Bipolar Operation With the DAC8541
_
+
OPA627
15 V
- 15 V
R2
10 k
Ω
V
OUT
SENSE
V
OUT
DAC8541 V
REF
H
V
REF
L
±
5 V
R1
10 k
Ω
0.1
µ
F 10
µ
F
V
REF
U2
U1
The bipolar configuration is accomplished by following the correct jumper
settings according to Table 3 - 5.
Table 3 - 5. Bipolar Operation Output Jumper Settings
Reference Jumper Position Function
W3 1 - 2 Negative rail supply of the op amp tied to - 15 V
W4 1 - 2 Positive rail supply of the op amp tied to 15 V
W5 Close Bipolar output of DAC is channeled to the output terminals
W6 Close Connect V
REF(H)
to the negative input of op amp for negative biasing
W7 Open Disconnect R8
An example in Figure 3 - 2 shows the sinusoidal signal in channel 1 being
amplified within the range of
±
V
REF(H)
shown in channel 2. The reference
voltage, V
REF(H)
, is set to 5 V, which is then supplied to the negative input of
U2 to bias the circuit to its negative rail. This provides an output of
±
5 V with