mma1270keg National Semiconductor Corporation, mma1270keg Datasheet - Page 5

• Manufacturer Part Number: mma1270keg
• Description: Freescale Semiconductor Technical Data
• Manufacturer: National Semiconductor Corporation

Sensors
Freescale Semiconductor
Pinout Description
Table 3. Pin Descriptions
14 thru 16
9 thru 13
V
Pin No.
1 thru 3
0.1 μF
Figure 5. SOIC Accelerometer with Recommended
DD
C1
4
5
6
7
8
LOGIC
INPUT
STATUS
Pin Name
Trim pins
STATUS
1
3
2
V
V
V
V
V
ST
V
V
V
V
OUT
V
OUT
—
DD
6
ST
SS
SS
8
DD
SS
SS
SS
SS
7
Connection Diagram
ST
V
V
V
V
V
DD
SS
SS
SS
SS
MMA1270KEG
Redundant connections to the internal
V
Output voltage of the accelerometer.
Logic output pin used to indicate fault.
The power supply input.
The power supply ground.
Logic input pin used to initiate self-test.
Used for factory trim.
Leave unconnected.
No internal connection.
Leave unconnected.
1
2
3
4
5
6
7
8
SS
and may be left unconnected.
V
OUT
Description
16
15
14
13
12
11
10
4
5
9
0.1 μF
C2
1 kΩ
R1
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
BASIC CONNECTIONS
STATUS
OUTPUT
SIGNAL
PCB Layout
NOTES:
Figure 6. Recommended PCB Layout for Interfacing
1. Use a 0.1 μF capacitor on V
2. Physical coupling distance of the accelerometer to the
3. Place a ground plane beneath the accelerometer to
4. Use an RC filter of 1 kΩ and 0.1 μF on the output of the
5. PCB layout of power and ground should not couple
6. Accelerometer and microcontroller should not be a
7. A/D sampling rate and any external power supply
STATUS
source.
microcontroller should be minimal.
reduce noise, the ground plane should be attached to
all of the open ended terminals shown in
accelerometer to minimize clock noise (from the
switched capacitor filter circuit).
power supply noise.
high current path.
switching frequency should be selected such that they
do not interfere with the internal accelerometer
sampling frequency. This will prevent aliasing errors.
V
OUT
V
V
ST
SS
DD
Accelerometer to Microcontroller
C
Power Supply
0.1 μF
1 kΩ
R
C
C
0.1 μF
0.1 μF
P1
P0
A/D In
V
RH
DD
to decouple the power
V
V
MMA1270KEG
SS
DD
Figure
C
0.1 μF
6.
5