DAC8565ICPWG4 Datasheet, PDF (38/49 Pages) Texas Instruments – 16-Bit, Quad Channel, Ultra-Low Glitch, Voltage Output

DAC8565
SBAS411C – JUNE 2007 – REVISED MARCH 2011
LAYOUT
A precision analog component requires careful layout,
adequate bypassing, and clean, well-regulated power
supplies.
The DAC8565 offers single-supply operation, and is
often 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
difficult it is to keep digital noise from appearing at
the output.
As a result of the single ground pin of the DAC8565,
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
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 GND connection, V_DD should be
connected to a 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 supply and
remove the high-frequency noise.
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