Freescale Semiconductor, Inc.
PCB Layout
BASIC CONNECTIONS
Pinout Description
STATUS
P1
ST
P0
16
15
14
13
12
11
10
9
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
ST
1
2
3
4
5
6
7
8
V
SS
V
A/D IN
OUT
R
C
0.1 µF
C
1 kΩ
0.01 µF
V
SS
V
DD
C
0.1 µF
V
OUT
STATUS
V
DD
V
RH
V
SS
V
DD
C
0.1 µF
POWER SUPPLY
Pin No.
Pin Name
Description
1 thru 3
V
SS
Redundant connections to the internal
V
and may be left unconnected.
SS
Figure 5. Recommended PCB Layout for Interfacing
Accelerometer to Microcontroller
4
ST
Logic input pin used to initiate self–
test.
5
V
Output voltage of the accelerometer.
Logic output pin used to indicate fault.
The power supply ground.
OUT
6
STATUS
NOTES:
7
8
V
SS
•
•
•
Use a 0.1 µF capacitor on V
source.
to decouple the power
DD
V
The power supply input.
DD
9 thru 13
Trim pins
Used for factory trim.
Leave unconnected.
Physical coupling distance of the accelerometer to the
microcontroller should be minimal.
14 thru 16
—
No internal connection.
Leave unconnected.
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 4.
6
•
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).
MMA1220D
STATUS
V
DD
LOGIC
INPUT
4
8
ST
R1
1 kΩ
5
OUTPUT
SIGNAL
V
V
OUT
DD
•
•
•
PCB layout of power and ground should not couple power
supply noise.
C1
0.1 µF
C2
Accelerometer and microcontroller should not be a high
current path.
0.01 µF
7
V
SS
A/Dsamplingrateandanyexternalpowersupplyswitching
frequency should be selected such that they do not inter-
fere with the internal accelerometer sampling frequency.
This will prevent aliasing errors.
Figure 4. SOIC Accelerometer with Recommended
Connection Diagram
2–22
www.motorola.com/semiconductors
Motorola Sensor Device Data
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MOTOROLA [ MOTOROLA ]
