DAC8550_15 Datasheet, PDF (20/28 Pages) Texas Instruments – 16-BIT, ULTRA-LOW GLITCH, VOLTAGE OUTPUT DIGITAL-TO-ANALOG CONVERTER

DAC8550
SLAS476E – MARCH 2006 – REVISED MARCH 2012
LAYOUT
A precision analog component requires careful layout,
adequate bypassing, and clean, well-regulated power
supplies.
The DAC8550 offers single-supply operation and is
used often 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
difficult it is to keep digital noise from appearing at
the output.
Due to the single ground pin of the DAC8550, all
return currents, including digital and analog return
currents for the DAC, must flow through a single
point. Ideally, GND would be connected directly to an
analog ground plane. This plane would be separate
from the ground connection for the digital
components until they were connected at the power-
entry point of the system.
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The power applied to V_DD 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.
This noise can easily couple into the DAC output
voltage through various paths between the power
connections and analog output.
As with the GND connection, V_DD should be
connected to a 5V 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, a 1μF to 10μF capacitor and 0.1μF bypass
capacitor are strongly recommended. In some
situations, additional bypassing may be required,
such as a 100μF electrolytic capacitor or even a Pi
filter made up of inductors and capacitors, all
designed to essentially low-pass filter the 5V supply,
removing the high-frequency noise.
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