Texas Instruments DAC8574, Руководство пользователя

Страница: 29 / 33

Optional Signal Conditioning Op-Amp (U8B)
3-5 EVM Operation
In unity gain, the OPA627 op-amp, U2, performs very well with very large
capacitive loads. Increasing the gain enhances the amplifier’s ability to drive
even more capacitance, and adding a load resistor would even improve the
capacitive load drive capability.
Table 3 - 5 shows the jumper setting configuration for a capacitive load drive.
Table 3 - 5. Capacitive Load Drive Output Jumper Settings
Jumper Setting
Reference
Unipolar Bipolar
Function
W3 Close Close
V
REF
H is disconnected from the inverting input of the output op-amp,
U2.
W5 2 - 3 1 - 2
Supplies power, V
SS
, to the negative rail of op-amp, U2, for bipolar
mode, or ties it to AGND for unipolar mode.
W15 Close Open
Capacitive load drive output of DAC is routed to pin 1 of W15 jumper and
maybe used as the output terminal.
3.5 Optional Signal Conditioning Op-Amp (U8B)
One part of the dual package op-amp, OPA2132 (U8), is used for reference
buffering (U8A) while the other is unused. This unused op-amp (U8B) is left
for whatever op-amp circuit application the user desires to implement. The
1206 footprint for the resistors and capacitors surrounding the U8B op-amp
are not populated and made available for easy configuration. TP6 and TP7 test
points are not installed either so it is up to the user on how to connect the
±
input
signals to this op-amp. No test point has been made available for the output
due to space restriction, but a wire can be simply soldered to the output of the
op-amp via unused component pads that connects to it.
Once the op-amp circuit is realized the configuration becomes easy by simply
populating the corresponding components that matches the circuit designed
and leaving all other unused component footprints unpopulated.