DAC8541 Datasheet, PDF (19/21 Pages) Texas Instruments – 16-BIT SINGLE CHANNEL, PARALLEL INPUT DIGITAL-TO-ANALOG CONVERTER WITH RAIL VOLTAGE OUTPUT

DAC8541
APPLICATION INFORMATION
SLAS353 − DECEMBER 2001
layout
A precision analog component requires careful layout, adequate bypassing, and clean, well-regulated power
supplies. The following measures should be taken to assure optimum performance of the DAC8541.
The DAC8541 offers dual-supply operation, as it can often be used in close proximity with digital logic,
microcontrollers, microprocessors, and digital signal processors. The more digital logic present in the design
and the higher the switching speed, the more important it becomes to separate the analog and digital ground
and supply planes at the DAC.
Because the DAC8541 has both analog and digital ground pins, return currents can be better controlled and
have less effect on the DAC’s output error. Ideally, AGND would be connected directly to an analog ground plane
and DGND to the digital ground plane. The analog ground plane would be separate from the ground connection
for the digital components until they were connected at the power entry point of the system.
The power applied to AV_DD and V_REFH (this also applies to V_REFL if not tied to AGND) should be well-regulated
and low-noise. Switching power supplies and dc/dc converters often have high-frequency glitches or spikes
riding on the output voltage. In addition, digital components can create similar high-frequency spikes as their
internal logic switches states. This noise can easily couple into the DAC output voltage through various paths
between the power connections and analog output.
As with the AGND connection, AV_DD should be connected to a 5-V power supply plane or trace that is separate
from the connection for digital logic until they are connected at the power entry point. In addition, the 1-µF to
10-µF and 0.1-µF bypass capacitors are strongly recommended. In some situations, additional bypassing may
be required, such as a 100-µF electrolytic capacitor or even a Pi filter made up of inductors and capacitors—all
designed to essentially lowpass filter the AV_DD supply, removing the high frequency noise.
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