STM32L152RBH6TR(2013) データシートの表示（PDF） - STMicroelectronics

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STM32L152RBH6TR
(Rev.:2013)

Ultra-low-power 32-bit MCU ARM®-based Cortex®-M3, 128KB Flash, 16KB SRAM, 4KB EEPROM, LCD, USB, ADC, DAC

STMicroelectronics 

STM32L151x6/8/B, STM32L152x6/8/B

Electrical characteristics

Figure 16. HSE oscillator circuit diagram

Rm

Lm

CO

Cm

Resonator

CL1

OSC_IN

Resonator

fHSE to core

RF

gm

Consumption

control

OSC_OUT

CL2

STM32

ai18235

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 29. 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).

Table 29. LSE oscillator characteristics (fLSE = 32.768 kHz)(1)

Symbol

Parameter

Conditions

Min Typ Max Unit

fLSE

Low speed external oscillator

frequency

32.768

kHz

RF Feedback resistor

Recommended load capacitance

C(2) versus equivalent serial

resistance of the crystal (RS)(3)

RS = 30 kΩ

ILSE LSE driving current

VDD = 3.3 V, VIN = VSS

IDD (LSE)

LSE oscillator current

consumption

VDD = 1.8 V

VDD = 3.0 V

VDD = 3.6V

gm Oscillator transconductance

tSU(LSE)(4) Startup time

3

VDD is stabilized

1.2

MΩ

8

pF

1.1 µA

450

600

nA

750

µA/V

1

s

1. Based on characterization, not tested in production.

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

design guide for ST microcontrollers”.

3. The oscillator selection can be optimized in terms of supply current using an high quality resonator with

small RS value for example MSIV-TIN32.768kHz. Refer to crystal manufacturer for more details;

4. 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 resonator and it can vary

significantly with the crystal manufacturer.

Doc ID 17659 Rev 8

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