Freescale Semiconductor MMA7260QT, Technical Data Manual

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Sensors
Freescale Semiconductor
5
MMA7260QT
BASIC CONNECTIONS
Pin Descriptions
Figure 4. Pinout Description
Figure 5. Accelerometer with Recommended
Connection Diagram
PCB Layout
Figure 6. Recommended PCB Layout for Interfacing
Accelerometer to Microcontroller
NOTES:
1. Verify V
DD
line has the ability to reach 2.2 V in < 0.1
ms as measured on the device at the V
DD
pin. Rise
times greater than this most likely will prevent start up
operation.
2. Physical coupling distance of the accelerometer to
the microcontroller should be minimal.
3. The flag underneath the package is internally
connected to ground. It is not recommended for the
flag to be soldered down.
4. 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 .
5. Use an RC filter with 1.0 k
Ω
and 0.1 µF on the
outputs of the accelerometer to minimize clock noise
(from the switched capacitor filter circuit).
6. PCB layout of power and ground should not couple
power supply noise.
7. Accelerometer and microcontroller should not be a
high current path.
8. 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 (11 kHz for the sampling
frequency). This will prevent aliasing errors.
9. PCB layout should not run traces or vias under the
QFN part. This could lead to ground shorting to the
accelerometer flag.
Table 4. Pin Descriptions
Pin No. Pin Name Description
1 g-Select1 Logic input pin to select g level.
2 g-Select2 Logic input pin to select g level.
3 V
DD
Power Supply Input
4 V
SS
Power Supply Ground
5 - 7 N/C No internal connection.
Leave unconnected.
8 - 11 N/C Unused for factory trim.
Leave unconnected.
12 Sleep Mode Logic input pin to enable product or
Sleep Mode.
13 Z
OUT
Z direction output voltage.
14 Y
OUT
Y direction output voltage.
15 X
OUT
X direction output voltage.
16 N/C No internal connection.
Leave unconnected.
Top View
15 16 14 13
12
11
10
1
2
3
4
5 6 7 8
9
g-Select1
N/C
N/C
N/C g-Select2
V
DD
V
SS
N/C
N/C N/C N/C N/C
X
OUT
Y
OUT
Sleep Mode
Z
OUT
Sleep Mode
V
DD
V
SS
0.1
μ
F
3
4
V
DD
0.1
μ
F
14
0.1
μ
F
15
12
X
OUT
Y
OUT
1 k
Ω
1 k
Ω
Logic
Input
2
1
0.1
μ
F
13
Z
OUT
1 k
Ω
Logic
Inputs
g-Select2
g-Select1
MMA7260QT
POWER SUPPLY
V
DD
V
SS
Sleep Mode
g-Select1
g-Select2
X
OUT
Y
OUT
Z
OUT
Accel
er
ometer
V
DD
V
SS
V
RH
P0
P1
P2
A/D
IN
A/D
IN
A/D
IN
C
C
C
R
R
R
C
C
C
Mi
cro
contro
ller
C
C