MPR083 datasheet(28/56 Pages) FREESCALE

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Hardware Description

Blood Pressure Monitor Design Reference Manual, Rev. 0

3-6

Freescale Semiconductor

Figure 3-2. Bottom Layer

3.10.1

Mechanical Characteristics

3.10.1.1

Conductor Width and Clearances

The PCB is a rectangle with a size of 6.45 inches by 4 inches with a thickness of 0.064 inch.

The trace widths and clearances for power lines and signal lines are in this table:

Lines that carry more current, such as the collector lines for the Darlington transistors, have a width of 15

mm. When line widths were determined, current values and copper thickness were taken into account.

Standard drill sizes were used for guaranteed manufacturability and ease of production.

3.10.1.2

Trace Angles

One source of RFI is an abrupt change of direction in a PCB track, which effectively looks like impedance

discontinuities and will radiate accordingly. For HCMOS designs it is important to ensure that 90-degree

track-direction changes do not occur. Also, from the mechanical point of view, a 90-degree angle is more

likely to be detached from the board.

Class

Width

Clearance

Regular signals

Power

MPR083 数据表(PDF) 28 Page - Freescale Semiconductor, Inc