ST10F272Z2Q3 STMicroelectronics, ST10F272Z2Q3 Datasheet - Page 153

• Manufacturer Part Number: ST10F272Z2Q3
• Description: MCU 16BIT 256KB FLASH 144-PQFP
• Manufacturer: STMicroelectronics
• Series: ST10r

Specifications of ST10F272Z2Q3

• Core Processor: ST10
• Core Size: 16-Bit
• Speed: 64MHz
• Connectivity: ASC, CAN, EBI/EMI, I²C, SSC, UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 111
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Ram Size: 20K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 24x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 144-QFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Other names: 497-5579

ST10F272Z2
Figure 45. 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
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
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.
Example of external network sizing
The following hypothesis are formulated in order to proceed in designing the external
network on A/D Converter input pins:
●
●
●
●
●
●
●
●
●
●
●
Anti-Aliasing Filter (f
Analog Source Bandwidth (V
Analog Signal Source Bandwidth (f
conversion Rate (f
Sampling Time (T
Pin Input Capacitance (C
Pin Input Routing Capacitance (C
Sampling Capacitance (C
Maximum Input Current Injection (I
Maximum Analog Source Voltage (V
Analog Source Impedance (R
Channel Switch Resistance (R
Sampling Switch Resistance (R
S
:
f
f
0
F
F
value:
F
= RC Filter pole)
Noise
S
C
):1 µs
):25 kHz
f
f
A
P1
)
S
-----------
V A2
):4 pF
):5 pF
V A
S
SW
):100 Ω
AD
=
Sampled Signal Spectrum (f
):500 Ω
P2
------------------------------------------------------------
C P1
):200 Ω
C F 2048 C S
T
f
2 f
INJ
F
0
C
):1 pF
):10 kHz
AM)
= f
0
C P1
≤ 2 R
):3 mA
>
≤ f
0
+
:12 V
A
(Anti-aliasing Filtering Condition)
C
C P2
f
0
+
is maximum, that is for instance 5 V),
(Nyquist)
F
S
C P2
C
; from the two charge balance equations
⋅
F
+
(Conversion Rate vs. Filter Pole)
C F
+
C F
+
C S
f
C
C
= conversion Rate)
Electrical characteristics
f
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