MMA26XXKW FREESCALE [Freescale Semiconductor, Inc], MMA26XXKW Datasheet - Page 20

• Manufacturer Part Number: MMA26XXKW
• Description: DSI Inertial Sensor
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

20
3.5
3.5.1 Transducer
3.5.2
data stream at a nominal frequency of 1 MHz.
3.5.3 Digital Signal Processing Block
the signal processing flow within the DSP block is shown in
Table 7. Signal Chain Characteristics
MMA26xxKW
A
B
C
D
E
F
The device transducer is an overdamped mass-spring-damper system described by the following transfer function:
where:
Reference
The sigma delta converter provides the interface between the g-cell and the DSP block. The output of the
A digital signal processing (DSP) block is used to perform signal filtering and compensation operations. A diagram illustrating
-------------------------------- -
D
10-Bit Output Scaling
Sinc Filter
n
= Damping Ratio
C = C
1 z D
Low Pass Filter
= Natural Frequency = 2
DSP Sampling
Compensation
C
C
Description
Interpolation
–
1 z 1 –
SINC Filter
TOP
BOT
Acceleration Signal Path
_OUT
–
–
g-cell
TOP
A
Converter
Section 2.8
- C
3
BOT
B
Sample Time
a
V = C x V
0
n
---------------------------------------------------------------------------- -
d
for transducer parameters.
( s)
11
11
16
16
16
16
1
1
1
+
+
=
n
d
12
12
C
X
V
INT1
/ C
f
n
X
z 1 –
z 1 –
Data Width
INT1
(Bits)
+
+
Low Pass Filter
20
26
26
1
n
d
13
13
Figure 12.
1
z 2 –
z 2 –
INTEGRATOR
Figure 13. Signal Chain Diagram
H s
1 - z
Over Range
FIRST
n
---------------------------------------------------------------------------- -
d
z
21
21
-1
(Bits
+
+
-1
1
4
=
n
d
22
22
------------------------------------------------------
s
Converter Block Diagram
2
z 1 –
z 1 –
+
Figure
Signal Width
2
+
+
(Bits)
2
n
d
12
12
10
10
10
1
23
23
13.
2
n
z 2 –
z 2 –
n s
Signal Noise
+
C
(Bits)
Compensation
2
n
2
4
4
3
INTEGRATOR
V = 2
SECOND
1 - z
z
-1
Signal Margin
-1
(Bits)
D
V
9
9
REF
Output
Scaling
QUANTIZER
Freescale Semiconductor, Inc.
Reference
Typical Block
1-BIT
ADC
DAC
tion 3.5.3.2
E
Latency
112/f
24/f
64/f
4/f
Interpolation
osc
osc
osc
osc
Sec-
converter is a
Section 3.5.3.1
Section 3.5.3.2
Section 3.5.3.3
Section 3.5.3.5
Section 3.5.3.5
Section 3.5.2
OUTPUT
Reference
_OUT
F
Sensors