Data Sheet - Freescale Semiconductor
Data Sheet - Freescale Semiconductor
Data Sheet - Freescale Semiconductor
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3.5.4 Digital-signal processor<br />
A digital-signal processor (DSP) is used to perform signal filtering and compensation. A diagram illustrating the signal processing<br />
flow within the DSP is shown in Figure 15.<br />
ΣΔ_OUT<br />
Table 33. Signal-chain characteristics<br />
MMA27XXW<br />
Description<br />
Sample<br />
time<br />
(μs)<br />
Figure 15. Signal-chain diagram<br />
<strong>Data</strong><br />
Width<br />
(Bits)<br />
Overrange<br />
(Bits<br />
Signal<br />
Width<br />
(Bits)<br />
A SD 1 1 1<br />
Signal<br />
Noise<br />
(Bits)<br />
Signal<br />
Margin<br />
(Bits)<br />
Typical<br />
Block<br />
Latency<br />
Reference<br />
Section 3.5.3<br />
B SINC filter 16 20 14 51 μs Section 3.5.4.1<br />
C Digital gain 16 20 14 Section 3.5.4.2<br />
D Low-pass filter 16 26 4 10 3 9 Section 3.5.4.3 Section 3.5.4.3<br />
E Compensation 16 26 4 10 3 9<br />
F Down sampling 256 26 4 10 3 9<br />
17 μs Section 3.5.4.4<br />
G Offset cancellation 256 26 4 10 3 9 Section 3.5.4.5 Section 3.5.4.5<br />
H<br />
A Sinc B Digital C Low-pass D E<br />
filter<br />
filter<br />
Gain<br />
Compensation<br />
Downsampling<br />
F<br />
Offset<br />
Offset Cancellation Cancellation<br />
Low-pass filter Output<br />
Rate Limiting<br />
H J<br />
Output<br />
Output<br />
Interpolation<br />
Scaling<br />
DSP sampling and interpolation 8 10 8 μs Section 3.5.4.7<br />
J 10-bit output scaling 1 10 1 μs Section 3.5.4.8<br />
Sensors<br />
40 <strong>Freescale</strong> <strong>Semiconductor</strong>, Inc.<br />
G
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