ST10F272M-4QR3 STMicroelectronics, ST10F272M-4QR3 Datasheet - Page 136

• Manufacturer Part Number: ST10F272M-4QR3
• Description: MCU 16BIT 256K FLASH 144-PQFP
• Manufacturer: STMicroelectronics
• Series: ST10r

Specifications of ST10F272M-4QR3

• Core Processor: ST10
• Core Size: 16-Bit
• Speed: 40MHz
• 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-MQFP, 144-PQFP
• Processor Series: ST10F27x
• Core: ST10
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

Electrical characteristics
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Moreover, it sources charge during the sampling phase, when the analog signal source is a
high-impedance source.
A real filter, can typically be obtained by using a series resistance with a capacitor on the
input pin (simple RC Filter). The RC filtering may be limited according to the value of source
impedance of the transducer or circuit supplying the analog signal to be measured. The filter
at the input pins must be designed taking into account the dynamic characteristics of the
input signal (bandwidth).
Figure 40. A/D converter input pins scheme
Input leakage and external circuit
The series resistor utilized to limit the current to a pin (see R
with a large source impedance can lead to a degradation of A/D converter accuracy when
input leakage is present.
Data about maximum input leakage current at each pin is provided in
characteristics on page
in general it decreases by one half for each 10° C decrease in temperature.
Considering that, for a 10-bit A/D converter one count is about 5mV (assuming V
5 V), an input leakage of 100 nA acting though an R
an error of exactly one count (5 mV); if the resistance were 100 kΩ the error would become
two counts.
Eventual additional leakage due to external clamping diodes must also be taken into
account in computing the total leakage affecting the A/D converter measurements. Another
contribution to the total leakage is represented by the charge sharing effects with the
sampling capacitance: being C
equal to the conversion rate of a single channel (maximum when fixed channel continuous
conversion mode is selected), it can be seen as a resistive path to ground. For instance,
assuming a conversion rate of 250 kHz, with C
obtained (R
channel). To minimize the error induced by the voltage partitioning between this resistance
V
A
Source
EQ
R
S
= 1/f
C
External circuit
C
S
, where f
126. Input leakage is greatest at high operating temperatures, and
R
Filter
F
C
F
R
R
C
R
R
R
C
C
S
F
F
L
SW
AD
P
S
S
C
substantially a switched capacitance, with a frequency
Source impedance
Filter resistance
Filter capacitance
Current limiter resistance
Channel selection switch impedance
Sampling switch impedance
Pin capacitance (two contributions, C
Sampling capacitance
represents the conversion rate at the considered
Current limiter
R
L
S
equal to 4 pF, a resistance of 1 MΩ is
C
L
P1
= 50 kΩ of external resistance leads to
P1
V
L
DD
and C
in
Figure
Internal circuit scheme
P2
)
selection
Channel
R
Table 56: DC
SW
C
40), in combination
P2
ST10F272M
Sampling
AREF
R
AD
C
S
=