STM32F101X8_10 Datasheet, PDF(46/85 Page) STMicroelectronics – Medium-density access line, ARM-based 32-bit MCU with 64 or 128 KB Flash, 6 timers, ADC and 7 communication interfaces

English

English German Russian Spanish Italian Polish Chinese Japanese Korean French Portuguese	Language :

STM32F101X8_10 Datasheet, PDF (46/85 Pages) STMicroelectronics – Medium-density access line, ARM-based 32-bit MCU with 64 or 128 KB Flash, 6 timers, ADC and 7 communication interfaces

◁

Electrical characteristics

STM32F101x8, STM32F101xB

Table 21. HSE 4-16 MHz oscillator characteristics(1)(2)

Symbol

Parameter

Conditions

Min Typ Max Unit

fOSC_IN Oscillator frequency

4

RF Feedback resistor

Recommended load capacitance

C

versus equivalent serial

RS = 30ï ï

resistance of the crystal (RS)(3)

i2

HSE driving current

VDD = 3.3 V, VIN = VSS

with 30 pF load

8 16 MHz

200

kï

30

pF

1 mA

gm Oscillator transconductance

tSU(HSE)(4) Startup time

Startup

VDD is stabilized

25

2

mA/V

ms

1. Resonator characteristics given by the crystal/ceramic resonator manufacturer.

2. Based on characterization, not tested in production.

3. The relatively low value of the RF resistor offers a good protection against issues resulting from use in a

humid environment, due to the induced leakage and the bias condition change. However, it is

recommended to take this point into account if the MCU is used in tough humidity conditions.

4. tSU(HSE) is the startup time measured from the moment it is enabled (by software) to a stabilized 8 MHz

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

with the crystal manufacturer

For CL1 and CL2, it is recommended to use high-quality external ceramic capacitors in the

5 pF to 25 pF range (typ.), designed for high-frequency applications, and selected to match

the requirements of the crystal or resonator (see Figure 21). CL1 and CL2 are usually the

same size. The crystal manufacturer typically specifies a load capacitance which is the

series combination of CL1 and CL2. PCB and MCU pin capacitance must be included (10 pF

can be used as a rough estimate of the combined pin and board capacitance) when sizing

CL1 and CL2. Refer to the application note AN2867 âOscillator design guide for ST

microcontrollersâ available from the ST website www.st.com.

Figure 21. Typical application with an 8 MHz crystal

Resonator with

integrated capacitors

CL1

CL2

8 MH z

resonator

REXT(1)

OSC_IN

RF

OSC_OU T

Bias

controlled

gain

fHS E

STM32F10xxx

ai14128b

1. REXT value depends on the crystal characteristics.

Low-speed external clock generated from a crystal/ceramic resonator

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

resonator oscillator. All the information given in this paragraph are based on characterization

results obtained with typical external components specified in Table 22. 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

46/85

Doc ID 13586 Rev 13

▷