SPC5644BF0VLT1 Freescale Semiconductor, SPC5644BF0VLT1 Datasheet - Page 75

• Manufacturer Part Number: SPC5644BF0VLT1
• Description: 32-bit Microcontrollers - MCU 1.5M FLASH, 192K RAM
• Manufacturer: Freescale Semiconductor

Specifications of SPC5644BF0VLT1

• Rohs: yes
• Core: e200
• Processor Series: MPC5644C
• Data Bus Width: 32 bit
• Maximum Clock Frequency: 120 MHz
• Program Memory Size: 1.5 MB
• Data Ram Size: 128 KB
• On-chip Adc: Yes
• Operating Supply Voltage: 0.3 V to 6.2 V
• Operating Temperature Range: - 40 C to + 105 C
• Package / Case: LQFP-208
• Mounting Style: SMD/SMT
• A/d Bit Size: 10 bit
• A/d Channels Available: 62
• Interface Type: CAN, I2C, SCI, SPI
• Maximum Operating Temperature: + 105 C
• Minimum Operating Temperature: - 40 C
• Number Of Programmable I/os: 177
• Number Of Timers: 32
• Program Memory Type: Flash
• Supply Voltage - Max: 6.2 V
• Supply Voltage - Min: 0.3 V

Calling f
according to the Nyquist theorem the conversion rate f
than or at least equal to twice the conversion period (T
which is just a portion of it, even when fixed channel continuous conversion mode is selected (fastest conversion rate at a
specific channel): in conclusion it is evident that the time constant of the filter R
sampling time T
sampling switch is closed.
The considerations above lead to impose new constraints on the external circuit, to reduce the accuracy error due to the voltage
drop on C
voltage on C
From this formula, in the worst case (when V
half a count, a constraint is evident on C
Freescale
0
S
the bandwidth of the source signal (and as a consequence the cut-off frequency of the anti-aliasing filter, f
; from the two charge balance equations above, it is simple to derive
S
:
S
, so the charge level on C
Anti-Aliasing Filter (f
Analog Source Bandwidth (V
f
Figure 18. Spectral representation of input signal
f
0
F
F
MPC5646C Microcontroller DataSheet, Rev. 5.1
= RC Filter pole)
F
Noise
value:
S
cannot be modified by the analog signal source during the time in which the
A
f
f
A
----------- -
V A2
)
V A
is maximum, that is for instance 5 V), assuming to accept a maximum error of
ADC_0 (10-bit)
ADC_1 (12-bit)
=
C
C
C F 2048 C S
must be at least 2f
C F
). Again the conversion period T
C P1
------------------------------------------------------- -
Sampled Signal Spectrum (f
C P1


T
f
2 f
F
8192
+
C
 f
0
2 R
C P2
f
0
+
(Anti-aliasing Filtering Condition)
C
C P2


(Nyquist)
F
C S
f
C
0
+
F
(Conversion Rate vs. Filter Pole)
C F
+
0
C F
; it means that the constant time of the filter is greater
+
C S
Equation 11
C
F
= conversion Rate)
C
f
F
C
is definitively much higher than the
C
is longer than the sampling time T
between the ideal and real sampled
f
Electrical Characteristics
F
Eqn. 12
Eqn. 13
),
Eqn. 11
75
S
,