DAC7573IPW datasheet(14/26 Pages) TI

14 / 26 page

PCB Layout

2-2

2.1

PCB Layout

The DACx573 EVM demonstrates the performance of the installed DAC

device under test, as specified in the data sheet. Careful analysis of the

physical restrictions and performance - degrading factors of the EVM is vital to

a successful design implementation. The obvious attributes that can cause

poor performance of the EVM can be avoided during schematic design by

proper component selection and correct circuit - design practices. The circuit

must include adequate bypassing, identifying, and managing the analog and

digital signals and understanding the mechanical attributes of the

components.

The less obvious part of the design lies in the PCB layout. The main concerns

are component placement and proper signal routing. The bypass capacitors

must be placed as close as possible to the pins and the analog and digital

signals must be properly separated from each other. The power and ground

planes are very important and require careful consideration. A solid plane is

preferred, but sometimes impractical. When solid planes are not possible, a

well - designed split plane can suffice. When considering a split - plane design,

analyze the component placement and carefully divide the board into its

analog and digital sections starting from the device under test. The ground

plane plays an important role in controlling noise and other effects that can

contribute to DAC output error. To ensure that return currents are handled

properly, route the appropriate signals only in their respective sections. Route

analog traces only directly above or below the analog section, and the digital

traces in the digital section. Minimize trace length, but use the widest possible

trace allowable in the design. These design practices are demonstrated in

subsequent figures in this section.

The DACx573 EVM board is constructed on a four - layer printed circuit board

using a copper - clad FR - 4 laminate material. The printed circuit board has a

dimension of 43,1800 mm (1.7000 inch) X 82,5500 mm (3.2500 inch), and the

board thickness is 1,5748 mm (0.0620 inch). Figure 2 - 1 through Figure 2 - 6

show the individual artwork layers.

DAC7573IPW Datasheet(PDF) 14 Page - Texas Instruments