MEMSIC MXD2020E/F Rev H Page 7 of 8 2/26/2007
TEMPERATURE OUTPUT NOISE REDUCTION
It is recommended that a simple RC low pass filter is used
when measuring the temperature output. Temperature
output is typically a very slow changing signal, so a very
low frequency filter eliminates erroneous readings that may
result from the presence of higher frequency noise. A
simple filter is shown in Figure 6.
Filtered TOUT
8.2K
0.1uFMEMSIC
Accel.
TOUT
Figure 6: Temperature Output Noise Reduction
POWER SUPPLY NOISE REJECTION
One capacitor is recommended for best rejection of power
supply noise (reference Figure 7 below). The capacitor
should be located as close as possible to the device supply
pin (V
DD
). The capacitor lead length should be as short as
possible, and surface mount capacitor is preferred. For
typical applications, the capacitor can be ceramic 0.1 μF.
VDA VDD
MEMSIC
Accelerometer
Power Supply
C1
0.1uF
Figure 7: Power Supply Noise Rejection
PCB LAYOUT AND FABRICATION SUGGESTIONS
1. The Sck pin should be grounded to minimize noise.
2. Liberal use of ceramic bypass capacitors is
recommended.
3. Robust low inductance ground wiring should be used.
4. Care should be taken to ensure there is “thermal
symmetry” on the PCB immediately surrounding the
MEMSIC device and that there is no significant heat
source nearby.
5. A metal ground plane should be added directly beneath
the MEMSIC device. The size of the ground plane
should be similar to the MEMSIC device’s footprint
and be as thick as possible.
6. Vias can be added symmetrically around the ground
plane. Vias increase thermal isolation of the device
from the rest of the PCB.
