ST7LITES2 View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

ST7LITES2

8-BIT MICROCONTROLLER WITH SINGLE VOLTAGE FLASH MEMORY, DATA EEPROM, ADC, TIMERS, SPI

STMicroelectronics 

ST7LITE0x, ST7LITESx

ADC CHARACTERISTICS (Cont’d)

Figure 81. RAIN max. vs fADC with CAIN=0pF1)

Figure 82. Recommended CAIN/RAIN values2)

45

1000

40

Cain 10 nF

4 MHz

35

100

Cain 22 nF

30

2 MHz

Cain 47 nF

25

1 MHz

10

20

15

10

1

5

0

0

10

30

70

0.1

0.01

0.1

1

10

CPARASITIC (pF)

fAIN(KHz)

Notes:

1. CPARASITIC represents the capacitance of the PCB (dependent on soldering and PCB layout quality) plus the pad ca-

pacitance (3pF). A high CPARASITIC value will downgrade conversion accuracy. To remedy this, fADC should be reduced.

2. This graph shows that depending on the input signal variation (fAIN), CAIN can be increased for stabilization and to allow

the use of a larger serial resistor (RAIN). It is valid for all fADC frequencies ≤ 4MHz.

13.11.1 General PCB Design Guidelines

To obtain best results, some general design and

layout rules should be followed when designing

the application PCB to shield the noise-sensitive,

analog physical interface from noise-generating

CMOS logic signals.

Properly place components and route the signal

traces on the PCB to shield the analog inputs. An-

alog 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.

106/125

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