ST10F280 datasheet(158/186 Pages) STMICROELECTRONICS

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ST10F280

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20.3.1 - A/D Converter Characteristics

VDD = 5V ± 10%, VSS = 0V, TA = -40 to +125°C, 4.0V ≤ VAREF ≤ VDD + 0.1V; VSS0.1V ≤ VAGND ≤ VSS + 0.2V

Notes: 1. VAIN may exceed VAGND or VAREF up to the absolute maximum ratings. However, the conversion result in these cases will be

X000h or X3FFh, respectively.

2. During the tS sample time the input capacitance Cain can be charged/discharged by the external source. The internal resistance of

the analog source must allow the capacitance to reach its final voltage level within the tS sample time. After the end of the tS sample

time, changes of the analog input voltage have no effect on the conversion result. Values for the tSC sample clock depend on the

programming. Referring to the tC conversion time formula of section 20.3.2 and to the table 39 of page 156:

- tS min = 2 tSC min = 2 tCC min = 2 x 24 x TCL = 48 TCL

- tS max = 2 tSC max = 2 x 8 tCC max = 2 x 8 x 96 TCL = 1536 TCL

TCL is defined in section 20.4.5 at page 159.

3. The conversion time formula is:

- tC = 14 tCC + tS + 4 TCL (= 14 tCC + 2 tSC + 4 TCL)

The tC parameter includes the tS sample time, the time for determining the digital result and the time to load the result register with

the result of the conversion. Values for the tCC conversion clock depend on the programming. Referring to the table 39 of page 156:

- tC min = 14 tCC min + tS min + 4 TCL = 14 x 24 x TCL + 48 TCL + 4 TCL = 388 TCL

- tC max = 14 tCC max + tS max + 4 TCL = 14 x 96 TCL + 1536 TCL + 4 TCL = 2884 TCL

4. This parameter is fixed by ADC control logic.

5. DNL, INL, TUE are tested at VAREF =5.0V, VAGND =0V, VCC = 4.9V. It is guaranteed by design characterization for all other

voltages within the defined voltage range.

‘LSB’ has a value of VAREF / 1024.

The specified TUE is guaranteed only if an overload condition (see IOV specification) occurs on maximum 2 not selected analog input

pins and the absolute sum of input overload currents on all analog input pins does not exceed 10mA.

6. The coupling factor is measured on a channel while an overload condition occurs on the adjacent not selected channel with an

absolute overload current less than 10mA.

7. Partially tested, guaranteed by design characterization.

8.To remove noise and undesirable high frequency components from the analog input signal, a low-pass filter must be connected at

the ADC input. The cut-off frequency of this filter should avoid 2 opposite transitions during the ts sampling time of the ST10 ADC:

- fcut-off ≤ 1 / 5 ts to 1/10 ts

where ts is the sampling time of the ST10 ADC and is not related to the Nyquist frequency determined by the tc conversion time.

Table 38 : A/D Converter Characteristics

Symbol

Parameter

Test Condition

Limit Values

Unit

minimum

maximum

VAREF

Analog Reference voltage

4.0

VDD + 0.1

VAIN

Analog input voltage

1 - 8

VAGND

VAREF

IAREF

Reference supply current

running mode

power-down mode

–

500

µA

CAIN

ADC input capacitance

Not sampling

Sampling

–

Sample time

2 - 4

48 TCL

1 536 TCL

Conversion time

3 - 4

388 TCL

2 884 TCL

DNL

Differential Nonlinearity

-0.5

+0.5

LSB

INL

Integral Nonlinearity

-1.5

+1.5

LSB

OFS

Offset Error

-1.0

+1.0

LSB

TUE

Total unadjusted error

-2.0

+2.0

LSB

RASRC

Internal resistance of analog source

tS in [ns]

2 - 7

–(tS / 150) - 0.25

Ω

Coupling Factor between inputs

6 - 7

–

1/500

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