Microchip Technology MCP355X, Руководство пользователя

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Installation and Operation
©
2006 Microchip Technology Inc. DS51598A-page 9
:
FIGURE 2-3: SINC filter response, MCP3551 device, simultaneous 50/60 Hz
Normal Mode Rejection.
2.3.3 PIC18F4550
The high speed USB PICmicro
®
microcontroller is used to connect to the PC and
quickly evaluate system performance. An In-Circuit Serial Programming™ (ICSP™)
connector is also included.
2.3.4 Filtering
Power supply filtering using passive components is included to improve the noise
performance of the MCP3551 device. The following circuit comprises the filtering on
the power supply, separating the analog and digital sections of the board:
2.3.5 DataView Noise Analysis
The system noise from the MCP355X Tiny Application Sensor Demo Board will be an
aperiodic signal not having any wave or shape. This randomness is best dealt with in
statistical properties, hence the RMS measurement of the Gaussian or normal distribu-
tion. When designing a system and attempting to measure the performance, the RMS
noise is much more repeatable than the peak-to-peak noise. Figure 2-4 shows two
different distributions with different RMS and PEAK values, representing two different
ADC output distributions.
-120
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
0 10 20 30 40 50 60 70 80 90 100 110
Frequency (Hz)
A
tten
u
ati
o
n
(d
B
)
USB Power Supply
Digital
Analog
Av
DD
, V
REF
10 μ F
10 μ F
100 Ω 10 μ H
1 k
Ω