STM8AF6228TD View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

STM8AF6228TD

Automotive 8-bit MCU, with up to32 Kbytes Flash, data EEPROM, 10-bit ADC, timers, LIN, SPI, I2C, 3 to 5.5V

STMicroelectronics 

STM8AF61xx, STM8AF62xx

Figure 16. HSE external clock source

VHSEH

VHSEL

Electrical characteristics

External clock

source

OSCIN

fHSE

STM8A

HSE crystal/ceramic resonator oscillator

The HSE clock can be supplied using a crystal/ceramic resonator oscillator of up to 16 MHz.

All the information given in this paragraph is based on characterization results with specified

typical external components. In the application, the resonator and the load capacitors have

to be placed as close as possible to the oscillator pins in order to minimize output distortion

and startup stabilization time. Refer to the crystal resonator manufacturer for more details

(frequency, package, accuracy...).

Table 31. HSE oscillator characteristics

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

RF

Feedback resistor

-

CL1/CL2(1) Recommended load capacitance

-

-

220

-

-

gm

Oscillator transconductance

-

5

-

tSU(HSE)(2) Startup time

VDD is

stabilized

-

2.8

-

kΩ

20

pF

-

mA/V

-

ms

1. The oscillator needs two load capacitors, CL1 and CL2, to act as load for the crystal. The total load capacitance (Cload) is

(CL1 * CL2)/(CL1 + CL2). If CL1 = CL2, Cload = CL1 / 2. Some oscillators have built-in load capacitors, CL1 and CL2.

2. This value is the startup time, measured from the moment it is enabled (by software) until a stabilized 16 MHz oscillation is

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

Figure 17. HSE oscillator circuit diagram

Rm

Lm

CO

Cm

Resonator

CL1

OSCIN

Resonator

fHSE to core

RF

gm

Current control

OSCOUT

CL2

STM8A

Doc ID 14952 Rev 6

55/89

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