MMA1252 Просмотр технического описания (PDF) - Freescale Semiconductor
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MMA1252 Datasheet PDF : 10 Pages
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Pinout Description
VSS
1
VSS
2
VSS
3
VOUT
4
STATUS
5
VDD
6
VSS
7
ST
8
BASIC CONNECTIONS
PCB Layout
16
N/C
15
N/C
14
N/C
13
N/C
12
N/C
11
N/C
10
N/C
9
N/C
STATUS
P1
ST
P0
VOUT
VSS
VDD
R
A/D In
1 k C 0.1 F
C 0.1 F
VRH
C 0.1 F
VSS
C 0.1 F
VDD
Table 3. Pin Descriptions
Pin No. Pin Name
Description
1 thru 3
4
5
VSS Redundant connections to the internal
VSS and may be left unconnected.
VOUT Output voltage of the accelerometer.
STATUS Logic output pin to indicate fault.
6
VDD The power supply input.
7
VSS The power supply ground.
8
ST
Logic input pin used to initiate self-test.
9 thru 13 Trim pins Used for factory trim. Leave
unconnected.
14 thru 16
—
No internal connection. Leave
unconnected.
VDD
LOGIC
INPUT
C1
0.1 F
MMA1252
8 ST
6 VDD
1
2
3
VVVSSSSSS
7 VSS
VOUT
5
R1
4 1 k
C2
0.1 F
STATUS
OUTPUT
SIGNAL
Power Supply
Figure 6. Recommended PCB Layout for Interfacing
Accelerometer to Microcontroller
NOTES:
1. Use a 0.1 F capacitor on VDD 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 k and 0.1 F 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.
Figure 5. SOIC Accelerometer with Recommended
Connection Diagram
Sensors
Freescale Semiconductor, Inc.
MMA1252
5
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