STM32F030F4 datasheet(51/88 Pages) STMICROELECTRONICS

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STM32F030x4 STM32F030x6 STM32F030x8

Electrical characteristics

Figure 14. Typical application with an 8 MHz crystal

REXT value depends on the crystal characteristics.

Low-speed external clock generated from a crystal resonator

The low-speed external (LSE) clock can be supplied with a 32.768 kHz crystal resonator

oscillator. All the information given in this paragraph are based on design simulation results

obtained with typical external components specified in Table 32. 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 on the resonator characteristics (frequency,

package, accuracy).

MS19876V1

OSC_OU T

OSC_IN

fHSE

CL1

8 MH z

resonator

REXT(1)

CL2

Resonator with

integrated capacitors

Bias

controlled

gain

Table 32. LSE oscillator characteristics (fLSE = 32.768 kHz)

Symbol

Parameter

Conditions(1)

Min(2)

Typ

Max(2)

Unit

IDD

LSE current consumption

LSEDRV[1:0]=00

lower driving capability

-0.5

µA

LSEDRV[1:0]= 01

medium low driving capability

-0.8

LSEDRV[1:0] = 10

medium high driving capability

-1.1

LSEDRV[1:0]=11

higher driving capability

-1.4

Oscillator

transconductance

LSEDRV[1:0]=00

lower driving capability

µA/V

LSEDRV[1:0]= 01

medium low driving capability

LSEDRV[1:0] = 10

medium high driving capability

LSEDRV[1:0]=11

higher driving capability

tSU(LSE)

(3)

Startup time

VDD is stabilized

1. Refer to the note and caution paragraphs below the table, and to the application note AN2867 “Oscillator

design guide for ST microcontrollers”.

2. Guaranteed by design, not tested in production.

tSU(LSE) is the startup time measured from the moment it is enabled (by software) to a stabilized 32.768 kHz

oscillation is reached. This value is measured for a standard crystal and it can vary significantly with the

crystal manufacturer

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