Texas Instruments DAC8560EVM-PDK - DAC8560 Performance Demonstration Kit DAC8560EVM-PDK DAC8560EVM-PDK Ficha De Dados
Códigos do produto
DAC8560EVM-PDK
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EVM Operation
3.4.1
Unity Gain Output
The buffered output configuration can be used to prevent loading the DAC8560, although it may present
some slight distortion because of the feedback resistor and capacitor. The user can tailor the feedback
circuit to closely match the desired wave shape by simply desoldering R6 and C12 and replacing them
with components of the desired values. Additionally, C12 can be eliminated and R6 can be replaced with a
0
some slight distortion because of the feedback resistor and capacitor. The user can tailor the feedback
circuit to closely match the desired wave shape by simply desoldering R6 and C12 and replacing them
with components of the desired values. Additionally, C12 can be eliminated and R6 can be replaced with a
0
Ω
resistor to simplify the feedback circuit.
shows the jumper setting for the unity gain configuration of the DAC external output buffer in
unipolar or bipolar mode.
Table 3. Unity Gain Output Jumper Settings
Jumper Setting
Reference
Function
Unipolar
Bipolar
W3
Open
Open
Disconnect V
REF
from the inverting input of the operational amplifier.
W5
2-3
1-2
Supplies V
SS
to the negative rail of operational amplifier or ties it to AGND.
W15
Open
Open
Disconnect the negative input of the operational amplifier from the gain resistor, R12.
3.4.2
Output Gain of Two or Bipolar Operation
Two types of configurations yield a gain of two output, depending on the setup of the jumpers W3 and
W15. These configurations allow the user to choose a DAC output having V
W15. These configurations allow the user to choose a DAC output having V
REF
as an offset or not.
shows the proper jumper settings of the EVM for the 2× gain output of the DAC.
Table 4. Gain of Two Output Jumper Settings
Jumper Setting
Reference
Function
Unipolar
Bipolar
Inverting input of the output operational amplifier, U2, is connected to V
REF
for use as its offset
Close
Close
voltage for bipolar operation. W15 jumper must be open.
W3
V
REF
is disconnected from the inverting input of the output operational amplifier, U2. W15
Open
Open
jumper must be close to achieve gain of 2 output.
Supplies power, V
SS
, to the negative rail of operational amplifier, U2, for bipolar mode, or ties it
W5
2-3
1-2
to AGND for unipolar mode.
Configures operational amplifier, U2, for a gain of 2 output without a voltage offset. W3 jumper
Close
Close
must be open.
W15
Inverting input of the operational amplifier, U2, is disconnected from the gain resistor, R12. W3
Open
Open
jumper must be close.
3.4.3
Capacitive Load Drive
Another output configuration option is to drive a wide range of capacitive load requirement. However, all
operational amplifiers under certain conditions may become unstable depending on the operational
amplifier configuration, gain, and load value. These are just few factors that can affect operational
amplifiers stability performance and should be considered when implementing.
operational amplifiers under certain conditions may become unstable depending on the operational
amplifier configuration, gain, and load value. These are just few factors that can affect operational
amplifiers stability performance and should be considered when implementing.
In unity gain, the OPA627 operational amplifier, U2, performs well with large capacitive loads. Increasing
the gain enhances the amplifier’s ability to drive even more capacitance, and by adding a load resistor
even improves the capacitive load drive capability.
the gain enhances the amplifier’s ability to drive even more capacitance, and by adding a load resistor
even improves the capacitive load drive capability.
11
SLAU211A – March 2007 – Revised November 2009
DAC8560 Evaluation Module
Copyright © 2007–2009, Texas Instruments Incorporated