STM8AF526ATCU View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

STM8AF526ATCU

Automotive 8-bit MCU, with up to 128 Kbyte Flash, data EEPROM, 10-bit ADC, timers, LIN, CAN, USART, SPI, I2C, 3 to 5.5 V

STMicroelectronics 

STM8AF526x/8x/Ax STM8AF6269/8x/Ax

Electrical characteristics

Table 32. HSE oscillator characteristics

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

RF

Feedback resistor

-

CL1/CL2(1) Recommended load capacitance

-

-

220

-

-

gm

Oscillator trans conductance

-

5

-

tSU(HSE)(2) Startup time

VDD is

stabilized

-

2.8

-

kΩ

20

pF

-

mA/V

-

ms

1.

The oscillator needs two load

(CL1 * CL2)/(CL1 + CL2). If CL1

c=aCpaLc2i,toCrlso,adC=L1CaLn1d/2.CSLo2,mtoe

act as load for the crystal. The total load capacitance

oscillators have built-in load capacitors, CL1 and CL2.

(CLoad)

is

2. This value is the startup time, measured from the moment it is enabled (by software) until a stabilized 24 MHz oscillation is

reached. It can vary with the crystal type that is used.

Figure 20. HSE oscillator circuit diagram

5P

/P

&2

&P

5HVRQDWRU

&/

26&,1

5HVRQDWRU

I+6(WRFRUH

5)

JP

&XUUHQWFRQWURO

&/

26&287

670

HSE oscillator critical gm formula

The crystal characteristics have to be checked with the following formula:

Equation 1

gm » gmcrit

where gmcrit can be calculated with the crystal parameters as follows:

Equation 2

gmcrit = (2 × Π × fHSE)2 × Rm(2Co + C)2

Rm: Notional resistance (see crystal specification)

Lm: Notional inductance (see crystal specification)

Cm: Notional capacitance (see crystal specification)

Co: Shunt capacitance (see crystal specification)

CL1 = CL2 = C: Grounded external capacitance

06Y9

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