ST72561AR7-Auto datasheet(300/324 Pages) STMICROELECTRONICS

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Electrical characteristics

ST72561-Auto

300/324

Doc ID 12370 Rev 8

0.1µF and optionally, if needed 10pF capacitors as close as possible to the ST7 power

supply pins and a 1 to 10µF capacitor close to the power source (see Figure 145).

●

The analog and digital power supplies should be connected in a star network. Do not

use a resistor, as VDDA is used as a reference voltage by the A/D converter and any

resistance would cause a voltage drop and a loss of accuracy.

●

Properly place components and route the signal traces on the PCB to shield the analog

inputs. Analog signals paths should run over the analog ground plane and be as short

as possible. Isolate analog signals from digital signals that may switch while the analog

inputs are being sampled by the A/D converter. Do not toggle digital outputs on the

same I/O port as the A/D input being converted.

Software filtering of spurious conversion results

For EMC performance reasons, it is recommended to filter A/D conversion outliers using

software filtering techniques.

Figure 145. Power supply filtering

ADC accuracy

Table 123.

ADC accuracy with fCPU = 8 MHz, fADC = 4 MHz RAIN < 10kW, VDD = 5V

Symbol

Parameter

Conditions

Typ

Max

Unit

|ET|

Total unadjusted error(1)

Data based on characterization results, not tested in production. ADC accuracy vs. negative injection

current: injecting negative current on any of the standard (non-robust) analog input pins should be avoided

as this significantly reduces the accuracy of the conversion being performed on another analog input. It is

recommended to add a Schottky diode (pin to ground) to standard analog pins which may potentially inject

negative current. The effect of negative injection current on robust pins is specified in Section 20.9: I/O port

pin characteristics.

Any positive injection current within the limits specified for IINJ(PIN) and ΣIINJ(PIN) in Section 20.9: I/O port

pin characteristics does not affect the ADC accuracy

4Note(2)

Under characterization.

LSB

|EO|

Offset error(1)

2.5

|EG|

Gain error(1)

|ED|

Differential linearity error(1)

1.5

|EL|

Integral linearity error(1)

VSS

VDD

0.1µF

VDD

ST72XXX

VDDA

VSSA

POWER

SUPPLY

SOURCE

ST7

DIGITAL NOISE

FILTERING

EXTERNAL

NOISE

FILTERING

1 to 10µF

0.1µF

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