STM32U545NET3QTR datasheet(193/283 Pages) STMICROELECTRONICS

193 / 283 page

DS14216 Rev 1

193/283

STM32U545xx

Electrical characteristics

258

Note:

For information on selecting the crystal, refer to the application note ‘Oscillator design guide

for STM8AF/AL/S, STM32 MCUs and MPUs’ (AN2867).

Figure 32. Typical application with a 32.768 kHz crystal

Note:

An external resistor is not required between OSC32_IN and OSC32_OUT and it is forbidden

to add one.

Gmcritmax

Maximum critical

crystal Gm

LSEDRV[1:0] = 00, low-drive capability

0.5

µA/V

LSEDRV[1:0] = 01, medium low-drive capability

0.75

LSEDRV[1:0] = 10, medium high-drive capability

1.7

LSEDRV[1:0] = 11, high-drive capability

2.7

CS_PARA

Internal stray

parasitic

capacitance(3)

tSU(LSE)(4) Startup time

VDD is stabilized

1. Specified by design. Not tested in production.

2. Refer to the note below this table.

3. CS_PARA is the equivalent capacitance seen by the crystal due to OSC32_IN and OSC32_OUT internal parasitic

capacitances.

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

Table 80. LSE oscillator characteristics (fLSE = 32.768 kHz)(1) (continued)

Symbol

Parameter

Conditions(2)

Min

Typ

Max

Unit

MSv70418V1

OSC32_IN

OSC32_OUT

Drive

programmable

amplifier

fLSE

32.768 kHz resonator

Resonator with integrated capacitors

CL1

CL2

Note:

CL1 and CL2 are external load capacitances. Cs (stray capacitance) is the sum of the device OSC32_IN/OSC32_OUT pins

equivalent parasitic capacitance (CS_PARA), and the PCB parasitic capacitance.

STM32U545NET3QTR Datasheet(PDF) 193 Page - STMicroelectronics

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