Datasheet

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DAC8551

SLAS429B – APRIL 2005 – REVISED OCTOBER 2006

The power applied to V

should be well-regulated

and low-noise. Switching power supplies and dc/dc

A precision analog component requires careful

converters often have high-frequency glitches or

layout, adequate bypassing, and clean,

spikes riding on the output voltage. In addition, digital

well-regulated power supplies.

components can create similar high-frequency

spikes. This noise can easily couple into the DAC

The DAC8551 offers single-supply operation, and it

output voltage through various paths between the

often is used in close proximity with digital logic,

power connections and analog output.

microcontrollers, microprocessors, and digital signal

processors. The more digital logic present in the

As with the GND connection, V

should be

design and the higher the switching speed, the more

connected to a 5V power-supply plane or trace that

difficult it is to keep digital noise from appearing at

is separate from the connection for digital logic until

the output.

they are connected at the power-entry point. In

addition, a 1 µ F to 10 µ F capacitor and 0.1 µ F bypass

Due to the single ground pin of the DAC8551, all

capacitor are strongly recommended. In some

return currents, including digital and analog return

situations, additional bypassing may be required,

currents for the DAC, must flow through a single

such as a 100 µ F electrolytic capacitor or even a Pi

point. Ideally, GND would be connected directly to an

filter made up of inductors and capacitors—all

analog ground plane. This plane would be separate

designed to essentially low-pass filter the 5V supply,

from the ground connection for the digital

removing the high-frequency noise.

components until they were connected at the

power-entry point of the system.

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