Access line, 16 MHz STM8S 8-bit MCU, up to 8 Kbytes Flash, data

Electrical characteristics STM8S103x

HSE user external clock

Subject to general operating conditions for V

DD

and T

A

.

Table 32.

HSE user external clock characteristics

Symbol Parameter Conditions

f

V

HSE_ext

HSEH

(1)

User external clock source frequency

OSCIN input pin high level voltage

V

HSEL

(1)

OSCIN input pin low level voltage

I

LEAK_HSE

OSCIN input leakage current V

SS

< V

IN

< V

DD

1.

Data based on characterization results, not tested in production.

Min

0

Max

16

Unit

MHz

0.7 x V

DD

V

DD

+ 0.3 V

V

SS

-1

0.3 x V

DD

+1

V

µA

Figure 17.

HSE external clock source

V

HSEH

V

HSEL

External clock source

OSCIN f

HSE

STM8

HSE crystal/ceramic resonator oscillator

The HSE clock can be supplied with a 1 to 16 MHz crystal/ceramic resonator oscillator. 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 start-up stabilization time. Refer to the crystal resonator manufacturer for more details

(frequency, package, accuracy...).

60/95 15441 Rev 3

STM8S103x Electrical characteristics

Table 33.

HSE oscillator characteristics

Symbol Parameter Conditions Min Typ Max Unit

f

HSE

R

F

C

(1)

External high speed oscillator frequency

Feedback resistor

Recommended load capacitance

(2)

C = 20 pF, f

OSC

= 16 MHz

1

220

16

20

6 (startup)

1.6

(stabilized)

(3)

MHz k

Ω pF

I

DD(HSE)

HSE oscillator power consumption

C = 10 pF, f

OSC

=16 MHz

6 (startup)

1.2

(stabilized)

(3)

mA g m t

SU(HSE)

(4)

Oscillator transconductance

Startup time V

DD

is stabilized

5

1 mA/V ms

1.

C is approximately equivalent to 2 x crystal Cload.

2.

The oscillator selection can be optimized in terms of supply current using a high quality resonator with small R m

Refer to crystal manufacturer for more details

value.

3.

Data based on characterization results, not tested in production.

4.

t

SU(HSE)

is the start-up time measured from the moment it is enabled (by software) to a stabilized 16 MHz oscillation is reached. This value is measured for a standard crystal resonator and it can vary significantly with the crystal manufacturer.

Figure 18.

HSE oscillator circuit diagram

R m

L m

C

O

C m

Resonator

C

L1

OSCIN

R

F g m f

HSE

to core

Consumption control

Resonator

STM8

OSCOUT

C

L2

HSE oscillator critical g m

formula

g mcrit

=

(

2

× Π × f

HSE

)

2

×

R m

(

2Co + C

)

2

R m

: Notional resistance (see crystal specification)

L m

: Notional inductance (see crystal specification)

C m

: Notional capacitance (see crystal specification)

Co: Shunt capacitance (see crystal specification)

C

L1

= C

L2

= C: Grounded external capacitance g m

>> g mcrit

15441 Rev 3 61/95