Datasheet

The Output Op Amp
3-6
easy access for monitoring up to eight DAC channels when stacking two
DACx574 EVMs together, as described in section 3.3.
The inverting input of U2 can be tied to AGND or to any voltage source through
TP2, which is selectable by the jumper configuration of W3. The voltage
source connected to TP2 is adjustable via potentiometer R14.
The following sections describe various configurations of the output amplifier,
U2.
3.4.1 Unity Gain Output (Default Configuration)
The buffered output configuration can be used to prevent loading the DAC.
However, it may present some slight distortion because of the feedback
resistor and capacitor. The user can tailor the feedback circuit to closely match
their desired wave shape by simply removing R7 and C11 and replacing them
with the desired values. R7 can be replaced with a zero-ohm resistor and C11
can be left open if desired.
Table 3-10 shows the jumper settings for the unity gain configuration of the
output buffer in unipolar or bipolar supply mode.
Table 3-10.Unity Gain Output Jumper Settings
Reference
Jumper Setting
Function
Reference
Unipolar Bipolar
Function
W3 Open Open
Disconnects TP2 input or AGND from the in-
verting input of the op-amp
W5 2-3 1-2
Supplies V
SS
to the negative rail of op-amp or
ties it to AGND
3.4.2 Output Gain of Two
Table 3-11 shows the proper jumper settings of the EVM for the 2× gain output
of the DAC.
Table 3-11.Gain of Two Output Jumper Settings
Reference
Jumper Setting
Function
Reference
Unipolar Bipolar
Function
W3 1-2 1-2
Inverting input of the output op-amp, U2, is
connected to AGND to set for a gain of 2.
W5 2-3 1-2
Supplies power, V
SS
, to the negative rail of
op-amp, U2, for bipolar supply mode, or ties
it to AGND for unipolar supply mode