DAC8562SDSCT Datasheet, PDF (43/58 Pages) Texas Instruments – DUAL 16-/14-/12-BIT, ULTRALOW-GLITCH, LOW-POWER, BUFFERED, VOLTAGE-OUTPUT DAC WITH 2.5-V, 4-PPM/°C INTERNAL REFERENCE IN SMALL 3-MM × 3-MM SON

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DAC8562, DAC8563
DAC8162, DAC8163
DAC7562, DAC7563
SLAS719D – AUGUST 2010 – REVISED AUGUST 2012
LAYOUT
A precision analog component requires careful layout, adequate bypassing, and clean, well-regulated power
supplies. The DAC756x, DAC816x, and DAC856x offer single-supply operation, and are 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 DAC756x, DAC816x, and DAC856x, 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. The
power applied to AV_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, AV_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 1-µF to 10-µF capacitor and 0.1-µF
bypass capacitor 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
low-pass filter the supply and remove the high-frequency noise.
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