DAC8551-Q1 Datasheet, PDF (20/28 Pages) Texas Instruments – Automotive 16-Bit, Ultralow-Glitch, Voltage-Output DAC

DAC8551-Q1
SLASEB8A – FEBRUARY 2016 – REVISED MARCH 2016
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9 Power Supply Recommendations
The DAC8551-Q1 can operate within the specified supply voltage range of 3.2 V to 5.5 V. 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. In order to further minimize noise from the power supply, a strong
recommendation is to include a 1 μF to 10 μF capacitor and 0.1 μF bypass capacitor. The current consumption
on the V_DD pin, the short-circuit current limit, and the load current for the device is listed in the Electrical
Characteristics table. The power supply must meet the aforementioned current requirements.
10 Layout
10.1 Layout Guidelines
A precision analog component requires careful layout, adequate bypassing, and clean, well-regulated power
supplies.
The DAC8551-Q1 offers 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.
Due to the single ground pin of the DAC8551-Q1, 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.
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 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 5 V supply, removing the high-frequency noise.
10.2 Layout Example
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Figure 40. Layout Diagram
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