ST10F276Z5 STMicroelectronics, ST10F276Z5 Datasheet - Page 193

• Manufacturer Part Number: ST10F276Z5
• Description: 16-BIT MICROCONTROLLER WITH MAC UNIT, UP TO 832 KBYTES FLASH MEMORY AND UP TO 68 KBYTES RAM
• Manufacturer: STMicroelectronics

Specifications of ST10F276Z5

• Single Voltage Supply: 5V ±10% (embedded regulator for 1.8 V core supply)

ST10F276Z5
In particular two different transient periods can be distinguished (see
1.
2.
The two transients above are not influenced by the voltage source that, due to the presence
of the R
with respect to the ideal source V
respect to the sampling time (T
Figure
Calling f
the anti-aliasing filter, f
least 2f
the conversion period (T
T
S
, which is just a portion of it, even when fixed channel continuous conversion mode is
A first and quick charge transfer from the internal capacitances C
sampling capacitance C
Considering a worst case (since the time constant in reality would be faster) in which
C
C
This relation can again be simplified considering only C
condition. In reality, the transient is faster, but the A/D converter circuitry has been
designed to also be robust in the very worst case: The sampling time T
much longer than the internal time constant:
The charge of C
voltage V
A second charge transfer also involves C
capacitance) through the resistance R
and C
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
R
Of course, R
combination with R
definitely bigger than C
charge transfer transient) will be much higher than V
respected (charge balance assuming now C
P2
S
L
49).
0
F
sizing is obtained:
0
, meaning that the constant time of the filter is greater than or at least equal to twice
are in series and the time constant is:
C
is reported in parallel to C
the bandwidth of the source signal (and as a consequence the cut-off frequency of
F
S
filter, cannot provide the extra charge to compensate for the voltage drop on C
were in parallel to C
A1
on the capacitance according to the following equation:
V A2 C S C P1 C P2 C F
L
must also be sized according to the current limitation constraints, in
P1
⋅
(
F
V A1
), according to Nyquist theorem the conversion rate f
and C
S
C
). Again the conversion period T
+
(source impedance) and R
0 τ 2
⋅
⋅
P1
(
S
C S
P2
, C
occurs (C
S
=
+
τ 1
). The filter is typically designed to act as anti-aliasing (see
+
τ 1
P1
is also redistributed on C
τ 2 R L
P2
A
10 R
C P1
; the time constant R
=
P1
<
<
(since the time constant in reality would be faster), the
and C
⋅ L
(
(
R SW
+
R SW
(call C
+
⋅
⋅
S
C P2
(
(
S
C S
is supposed initially completely discharged):
C S
)
+
L
+
, then the final voltage V
=
: Again considering the worst case in which C
P
R AD
R AD
)
V A C F
+
+
F
= C
=
C P1
C P1
(that is typically bigger than the on-chip
⋅
V A
S
)
) C
P1
⋅
•
already charged at V
---------------------- -
C P
+
C P C S
+
+
⋅
F
+ C
V A1
(
C P2
C P2
S
C P1
(filter resistance). Being that C
+
⋅
F
«
P2
C
C S
A1
T
⋅
(
C
S
)
)
F
S
C P1 C P2
), the two capacitances C
+
. The following equation must be
, determining a new value of the
≤
is longer than the sampling time
of the filter is very high with
S
C P2
T S
as an additional worst
+
)
Electrical characteristics
A2
+
Figure
P1
(at the end of the
C S
A1
and C
)
S
):
, a constraint on
S
48):
C
is always
must be at
P2
to the
P
193/239
F
and
is
P2
S