ST72622L2M1L View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

ST72622L2M1L

LOW SPEED USB 8-BIT MCU WITH 3 ENDPOINTS, FLASH OR ROM MEMORY, LVD, WDG, 10-BIT ADC, 2 TIMERS, SCI, SPI

STMicroelectronics 

ST7262

ADC CHARACTERISTICS (Cont’d)

ADC Accuracy with fCPU=8 MHz, fADC=4 MHz RAIN< 10kΩ

Symbol

Parameter

Conditions

|ET| Total unadjusted error

|EO| Offset error

|EG| Gain Error

|ED| Differential linearity error

|EL| Integral linearity error

VDD= 4V-5.5V

Figure 90. ADC Accuracy Characteristics

Typ

3 1)

1 1)

0.7 1)

1.3 1)

2.9 1)

Max

2 1)

2 1)

2 1)

5 1)

Unit

LSB

1023

1022

1021

7

6

5

4

3

2

1

Digital Result ADCDR

1LSBIDEA L = V-----D-----D----1A---0---–-2---V-4----S----S-----A--

(2)

ET

EO

EL

1 LSBIDEAL

0

1234567

VSSA

EG

(1) Example of an actual transfer curve

(2) The ideal transfer curve

(3) End point correlation line

(3)

(1)

ED

ET=Total Unadjusted Error: maximum deviation

between the actual and the ideal transfer curves.

EO=Offset Error: deviation between the first actual

transition and the first ideal one.

EG=Gain Error: deviation between the last ideal

transition and the last actual one.

ED=Differential Linearity Error: maximum deviation

between actual steps and the ideal one.

EL=Integral Linearity Error: maximum deviation

between any actual transition and the end point

correlation line.

1021 1022 1023 1024

VDDA

Vin (LSBIDEAL)

Notes:

1) Not tested in production, guaranteed by characterization.

2) ADC Accuracy vs. Negative Injection Current:

Injecting negative current on any of the analog input pins significantly reduces the accuracy of the conversion being per-

formed on another analog input.

For IINJ-=0.8mA, the typical leakage induced inside the die is 1.6µA and the effect on the ADC accuracy is a loss of 4 LSB

for each 10KΩ increase of the external analog source impedance. It is recommended to add a Schottky diode (pin to

ground) to analog pins which may potentially inject negative current. Any positive injection current within the limits spec-

ified for IINJ(PIN) and ΣIINJ(PIN) in Section 12.8 does not affect the ADC accuracy.

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