STM32L021D4 datasheet(83/114 Pages) STMICROELECTRONICS

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STM32L021x4

Electrical characteristics

Figure 26. ADC accuracy characteristics

Total unadjusted error

1.65 V < VDDA < 3.6 V, range

1/2/3, TSSOP14 package

-3

LSB

Offset error

2.5

Gain error

2.5

Integral linearity error

1.5

2.5

Differential linearity error

1.7

ENOB

Effective number of bits

9.5

10.5

bits

Effective number of bits (16-bit mode

oversampling with ratio =256)(5)

10.7

11.6

SINAD

Signal-to-noise distortion

SNR

Signal-to-noise ratio

Signal-to-noise ratio (16-bit mode

oversampling with ratio =256)(5)

THD

Total harmonic distortion

-75

-63

1. ADC DC accuracy values are measured after internal calibration.

2. 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.

Any positive injection current within the limits specified for IINJ(PIN) and ΣIINJ(PIN) in Section 6.3.12 does not affect the ADC

accuracy.

3. Better performance may be achieved in restricted VDDA, frequency and temperature ranges.

4. In TSSOP14 package, where VDDA pin is shared with VDD pin, I/O toggling should be minimized to reach the values given in

the above table. I/O toggling with loaded I/O pins can generate ripple on VDD/VDDA and degrade the ADC accuracy.

5. This number is obtained by the test board without additional noise, resulting in non-optimized value for oversampling mode.

Table 55. ADC accuracy(1)(2)(3)(4)

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

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