AN-MPU-x000A-01
Document Number: AN-MPU-x000A-01
Page 9 of 14
Revision: 1.1
Date: 06/12 /2015
4.4.
PCB TRACE LAYOUT
Traces connected to pads should be as symmetrical as possible. Symmetry and balance for pad traces will improve component self-
alignment and lead to better control of solder paste reduction after the reflow process.
For high speed interfaces, such as I2C and SPI, all clock and data traces should be routed with the same length, and away from the
serial bus or other high speed traces. Power traces should also be routed away from high speed signals, and kept 10mil or thicker for
a 0.5oz copper PCB. Provide a solid ground return path, with traces 10mil or thicker for a 0.5oz copper PCB.
The PCB Layout Diagram and recommended pad size is provided within the MPU device Product Specification documents. Figure 8
below provides an example of a PCB Layout Diagram from PS-MPU-6000A-00 (revision 3.3). Please use the most recent revision of
the product specification for the device that you are working with.
Figure 8. Exposed Pad (EP) Dimensions and Sizing Recommended for MPU-6050
Place vias outside of the solder area and near the pad, as they can cause elevation changes. Do not place vias within the pad outline;
as vias and their related plating materials can contribute to an orientation offset and non-uniform mechanical package stress.
Eight NC (No Connect) pins can be soldered to the board for mechanical stability, but those pads on the board should not be
connected electrically.
4.5.
NOISE SOURCES
Physical noise sources can cause unnecessary vibration and contaminate the desired measurement. The MPU should be mounted in
a rigid location, which will have minimal external vibration.
Moving parts which cause vibration and are not intended to be measured, such as speakers, vibration/haptic motors, buttons, etc.
(figure 9), should be mechanically isolated from the MPU.
Figure 9. Speaker and Tactile Vibrations Can be Interpreted as Noise by the MPU
Active signals may harmonically couple with the gyro MEMS devices, compromising gyro response. InvenSense MPU gyroscopic
sensors operate at drive frequencies: X = 33+/-3 kHz, Y = 30+/-3 kHz, and Z = 27+/-3 kHz. To avoid harmonic coupling don’t route
active signals directly below or near the package. For best performance, design a ground plane under the EP to reduce PCB signal
noise. If the MPU device is stacked under an adjacent PCB board, design a ground plane to shield the MPU from the adjacent PCB.
Electrical sources, such as a switched-mode power supply (SMPS) shown in figure 10, can cause high frequency vibration. SMPS with
switching noise below 150 kHz (including Harmonics) can reduce device performance.
Powered devices that may generate acceleration or vibration to the MEMS structures can cause damage to MEMS devices. Examples
of such components are inductors, capacitors, PMIC, haptic motors, speakers, etc. If there is a source of acceleration or vibration in
PCB Layout Diagram
SYMBOLS
DIMENSIONS IN MILLIMETERS
NOM
Nominal Package I/O Pad Dimensions
e
Pad Pitch
0.50
b
Pad Width
0.25
L
Pad Length
0.35
L1
Pad Length
0.40
D
Package Width
4.00
E
Package Length
4.00
D2
Exposed Pad Width
2.70
E2
Exposed Pad Length
2.60
I/O Land Design Dimensions (Guidelines )
D3
I/O Pad Extent Width
4.80
E3
I/O Pad Extent Length
4.80
c
Land Width
0.35
Tout
Outward Extension
0.40
Tin
Inward Extension
0.05
L2
Land Length
0.80
L3
Land Length
0.85
PCB Dimensions Table (for PCB Lay-out Diagram)
