TRK-USB-MPC5643L Freescale Semiconductor, TRK-USB-MPC5643L Datasheet - Page 96

• Manufacturer Part Number: TRK-USB-MPC5643L
• Description: Development Boards & Kits - Other Processors StarTrakMiniUSG MPC5643L
• Manufacturer: Freescale Semiconductor

Specifications of TRK-USB-MPC5643L

• Rohs: yes
• Product: Starter Kits
• Tool Is For Evaluation Of: MPC5643L
• Core: Five Stage Pipeline
• Interface Type: LIN, DSPI
• Operating Supply Voltage: 3 V to 3.6 V
• Data Bus Width: 32 bit, 64 bit
• Description/function: Starter Kit for MPC5643L
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• For Use With: MPC5643L

Electrical characteristics
The two transients above are not influenced by the voltage source that, due to the presence of the R
provide the extra charge to compensate the voltage drop on C
the filter is very high with respect to the sampling time (T
96
•
faster) in which C
and the time constant is
Equation 5
faster, but the A/D converter circuitry has been designed to be robust also in the very worst case: the sampling time T
is always much longer than the internal time constant:
The charge of C
according to
A second charge transfer involves also C
R
would be faster), the time constant is:
In this case, the time constant depends on the external circuit: in particular imposing that the transient is completed
well before the end of sampling time T
Of course, R
impedance) and R
(at the end of the charge transfer transient) will be much higher than V
balance assuming now C
L
: again considering the worst case in which C
can again be simplified considering only C
L
Equation
V A2
shall be sized also according to the current limitation constraints, in combination with R
P1
P2
F
and C

(filter resistance). Being C
is reported in parallel to C

C S C P1 C P2 C F
7:
P2
V A1
S
+
already charged at V
is redistributed also on C
10  2
MPC5643L Microcontroller Data Sheet, Rev. 8.1


+

C S
 1
 1
 2 R L
=
=
+
10 R L


S
+
C P1


, a constraints on R
R SW
F
R SW

(that is typically bigger than the on-chip capacitance) through the resistance


+


C P2
=
+
C S
F
P1
+
A1

definitively bigger than C
V A C F
P2
C S
R AD
R AD
S
(call C
):
). The filter is typically designed to act as anti-aliasing.
+

and C
S

+
C P1
S
=
, determining a new value of the voltage V

C P1
with respect to the ideal source V

S

V A
P

as an additional worst condition. In reality, the transient is
S
C S T S
+
+
= C
-------------------- -
C P
C P C S
were in parallel to C
L
+
V A1
C P2

«
sizing is obtained:
P1
+
C P2


C P1
C S
+ C




C P1 C P2

P2
+
), the two capacitances C
C P2
T S
A1
+
.
P1
Equation 10

, C
P2
P1
+
C S
(since the time constant in reality
and C

must be respected (charge
A
S
, then the final voltage V
; the time constant R
F
C
Freescale Semiconductor
F
P
filter, is not able to
A1
and C
on the capacitance
S
S
are in series,
(source
Eqn. 10
Eqn. 5
Eqn. 6
Eqn. 7
Eqn. 8
Eqn. 9
F
C
F
A2
of
S