ST10F272B_12 STMICROELECTRONICS [STMicroelectronics], ST10F272B_12 Datasheet - Page 148

• Manufacturer Part Number: ST10F272B_12
• Description: 16-bit MCU with 256 Kbyte Flash memory and 12/20 Kbyte RAM
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Electrical characteristics
148/188
Figure 41. Anti-aliasing filter and conversion rate
The considerations above lead to impose new constraints to the external circuit, to reduce
the accuracy error due to the voltage drop on C
above, it is simple to derive the following relation between the ideal and real sampled
voltage on C
Equation 8
From this formula, in the worst case (when V
assuming to accept a maximum error of half a count (~2.44mV), it is immediately evident a
constraints on C
Equation 9
In the next section an example of how to design the external network is provided, assuming
some reasonable values for the internal parameters and making hypothesis on the
characteristics of the analog signal to be sampled.
S
:
F
value:
Doc ID 11917 Rev 3
-----------
V A2
V A
=
------------------------------------------------------------
C P1
C F
C P1
>
+
2048 C S
A
C P2
+
is maximum, that is for instance 5V),
S
C P2
; from the two charge balance equations
⋅
+
C F
+
C F
+
C S
ST10F272B/ST10F272E