DAC7568IAPWR.A datasheet(53/72 Pages) TI2

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DAC7568, DAC8168, DAC8568

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SBAS430F – JANUARY 2009 – REVISED APRIL 2018

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10 Layout

10.1 Layout Guidelines

A precision analog component requires careful layout, adequate bypassing, and clean, well-regulated power

supplies.

The DAC7568, DAC8168, and DAC8568 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 DAC7568, DAC8168, and DAC8568, 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 AVDD 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, AVDD 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.

DAC7568IAPWR.A bảng dữ liệu(PDF) 53 Page - Texas Instruments