STM32F100V6T7BTR データシートの表示（PDF） - STMicroelectronics

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STM32F100V6T7BTR

Low & medium-density value line, advanced ARM®-based 32-bit MCU with 16 to 128 KB Flash, 12 timers, ADC, DAC & 8 comm interfaces

STMicroelectronics 

STM32F100x4, STM32F100x6, STM32F100x8, STM32F100xB

Electrical characteristics

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

Note:

Caution:

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 resonator manufacturer for more details on the resonator

characteristics (frequency, package, accuracy).

For CL1 and CL2 it is recommended to use high-quality ceramic capacitors in the 5 pF to

15 pF range selected to match the requirements of the crystal or resonator. 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.

Load capacitance CL has the following formula: CL = CL1 x CL2 / (CL1 + CL2) + Cstray where

Cstray is the pin capacitance and board or trace PCB-related capacitance. Typically, it is

between 2 pF and 7 pF.

For further details, refer to the application note AN2867 “Oscillator design guide for ST

microcontrollers” available from the ST website www.st.com.

To avoid exceeding the maximum value of CL1 and CL2 (15 pF) it is strongly recommended

to use a resonator with a load capacitance CL ≤ 7 pF. Never use a resonator with a load

capacitance of 12.5 pF.

Example: if you choose a resonator with a load capacitance of CL = 6 pF, and Cstray = 2 pF,

then CL1 = CL2 = 8 pF.

Symbol

Table 22. LSE oscillator characteristics (fLSE = 32.768 kHz)(1)

Parameter

Conditions

Min Typ Max Unit

RF

Feedback resistor

-

-

5

-

MΩ

CL1 CL2(2)

Recommended load capacitance

versus equivalent serial

resistance of the crystal (RS)(3)

RS = 30 KΩ

-

-

15 pF

I2

LSE driving current

VDD = 3.3 V VIN = VSS

-

-

1.4 µA

gm

Oscillator transconductance

-

5

-

- µA/V

TA = 50 °C

-

1.5

-

TA = 25 °C

-

2.5

-

TA = 10 °C

-

4

-

tSU(LSE)(4) Startup time

VDD is

stabilized

TA = 0 °C

TA = -10 °C

-

6

-

s

-

10

-

TA = -20 °C

-

17

-

TA = -30 °C

-

32

-

TA = -40 °C

-

60

-

1. Guaranteed by characterization results.

2. Refer to the note and caution paragraphs above the table.

3.

The oscillator selection can be optimized in terms of supply current using an high

example MSIV-TIN32.768 kHz. Refer to crystal manufacturer for more details

quality

resonator

with

small

RS

value

for

4.

rteSaUc(LhSeEd).

is the startup

This value is

time measured

measured for a

from the moment it is enabled (by software)

standard crystal and it can vary significantly

to a stabilized 32.768 kHz oscillation

with the crystal manufacturer

is

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