Datasheet
MMA1211KEG
Sensors
Freescale Semiconductor 5
BASIC CONNECTIONS
Pinout Description
Figure 5. SOIC Accelerometer with Recommended
Connection Diagram
PCB Layout
Figure 6. Recommended PCB Layout for Interfacing
Accelerometer to Microcontroller
NOTES:
1. Use a 0.1 μF capacitor on V
DD
to decouple the power
source.
2. Physical coupling distance of the accelerometer to the
microcontroller should be minimal.
3. Place a ground plane beneath the accelerometer to
reduce noise, the ground plane should be attached to
all of the open ended terminals shown in Figure 6.
4. Use an RC filter of 1 kΩ and 0.01 μF on the output of
the accelerometer to minimize clock noise (from the
switched capacitor filter circuit).
5. PCB layout of power and ground should not couple
power supply noise.
6. Accelerometer and microcontroller should not be a
high current path.
7. A/D sampling rate and any external power supply
switching frequency should be selected such that they
do not interfere with the internal accelerometer
sampling frequency. This will prevent aliasing errors.
Table 3. Pin Descriptions
Pin No. Pin Name Description
1 thru 3 — Leave unconnected
4 ST Logic input pin used to initiate self-test
5 V
OUT
Output voltage of the accelerometer
6 STATUS Logic output pin to indicate fault
7 V
SS
The power supply ground
8 V
DD
The power supply input
9 thru 13 Trim pins Used for factory trim. Leave
unconnected
14 thru 16 — No internal connection. Leave
unconnected
N/C
N/C
N/C
ST
V
OUT
STATUS
V
SS
V
DD
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
MMA1211KEG
ST
V
OUT
Output
Signal
R1
1 kΩ
5
C2
0.01 μF
4
7
Logic
Input
V
DD
C1
0.1 μF
6
STATUS
8
V
DD
V
SS
P0
A/D In
V
RH
V
SS
V
DD
ST
V
OUT
V
SS
V
DD
0.01 μF1 kΩ
0.1 μF
0.1 μF
Power Supply
0.1 μF
P1
STATUS
Microcontroller
Accelerometer
C
C
C
C
R